Vol. 76 Tuesday, No. 50 March 15, 2011

Part III

Department of the Interior

Fish and Wildlife Service

50 CFR Part 17 Endangered and Threatened Wildlife and Plants; Withdrawal of Proposed Rule To List the Flat-Tailed Horned Lizard as Threatened; Proposed Rule

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DEPARTMENT OF THE INTERIOR lizard found in the Sonoran Desert of hybrids between flat-tailed and desert the southwestern United States and horned lizards have been observed in Fish and Wildlife Service northwestern Mexico. All of the species the vicinity of Ocotillo, California of lizards in the genus Phrynosoma—the (Stebbins 2003, p. 302). Additionally, 50 CFR Part 17 horned lizards—have dorso-ventrally the regal horned lizard (P. solare) also [Docket No. FWS–R8–ES–2010–0008; MO flattened, ‘‘pancake-like’’ bodies; spiny occurs in northwestern Sonora, Mexico 92210–0–0008] scales; head spines or ‘‘horns’’; cryptic (Rorabaugh 2008, p. 39); we are not coloration; and certain similar aware of hybridization with this species. RIN 1018–AX07 behavioral traits (Sherbrooke 2003, pp. 4–17; Stebbins 2003, p. 299; Leache´ and Life History Endangered and Threatened Wildlife McGuire 2006, p. 629). and Plants; Withdrawal of Proposed Flat-tailed horned lizards are Among horned lizard species, the flat- oviparous (egg-laying), are early Rule To List the Flat-Tailed Horned tailed horned lizard has particularly Lizard as Threatened maturing, and may produce multiple long and sharp horns (Funk 1981, p. clutches within a breeding season AGENCY: Fish and Wildlife Service, 281.1; Sherbrooke 2003, p. 40; Young et (Howard 1974, p. 111; Turner and Interior. al. 2004a, p. 65). Other characteristics Medica 1982, p. 819), which, when it ACTION: Proposed rule; withdrawal. that help distinguish flat-tailed horned occurs, results in two groups of lizards from other members of the genus individuals in a single year that are all SUMMARY: We, the U.S. Fish and include a dark line down the middle of generally the same age (that is, two Wildlife Service (Service), determine the back (vertebral stripe), lack of cohorts). However, some authors that the listing of the flat-tailed horned external ear openings, two rows of question whether the observed two lizard (Phrynosoma mcallii) as a fringe scales, an unspotted vent, and— cohorts is the result of individual threatened species under the as indicated by its common name—a females producing two clutches in a Endangered Species Act of 1973, as long, broad, flattened tail (Funk 1981, p. year or whether different groups of amended (Act), is not warranted, and 281.1; Sherbrooke 2003, p. 40). The flat- females lay eggs at different times (Muth we therefore withdraw our November tailed horned lizard is average in size and Fisher 1992, p. 46; Young and 29, 1993, proposed rule to list it under when compared to other horned lizard Young 2000, p. 11). Flat-tailed horned the Act. We made this determination in species. Flat-tailed horned lizards lizards produce relatively small clutches this withdrawal because threats to the become adults when about 60 to 64 of eggs (mean clutch size = 4.7; range = species as identified in the 1993 millimeters (mm) (2.4 to 2.5 inches (in)) 3 to 7) (Howard 1974, p. 111) compared proposed rule are not as significant as long, not including the tail (snout-to- to most other horned lizards (Sherbrook earlier believed, and available data do vent length), and may grow to be about 2003, p. 139). The first cohort hatches not indicate that the threats to the 87 mm (3.4 in) long (Young and Young in July to August (Muth and Fisher species and its habitat, as analyzed 2000, p. 34; Rorabaugh and Young 2009, 1992, p. 19; Young and Young 2000, p. p. 182). The dorsal coloration of flat- under the five listing factors described 13), and when it occurs, the second tailed horned lizards varies and closely in section 4(a)(1) of the Act, are likely cohort may be produced in September matches the colors of the desert soils on to endanger the species in the (Howard 1974, p. 111; Muth and Fisher which they live, ranging from pale gray foreseeable future throughout all or a 1992, p. 19). Hatchlings from the first to light rust-brown, while their ventral significant portion of its range. cohort may reach sexual maturity after coloration is white or cream-colored DATES: The November 29, 1993 (58 FR their first winter season, whereas (Funk 1981, p. 281.1; Flat-tailed Horned 62624), proposal to list the flat-tailed individuals that hatch later may require Lizard Interagency Coordinating horned lizard as a threatened species is an additional growing season to mature Committee [FTHLICC] 2003, p. 1; withdrawn as of March 15, 2011. (Howard 1974, p. 111). Flat-tailed Stebbins 2003, p. 304). First described ADDRESSES: This withdrawal of the by Hallowell in 1852, no subspecies horned lizards typically live for 4 years, proposed rule is available on the have been described or are recognized or rarely even 6 years, in the wild Internet at http://www.regulations.gov. for the flat-tailed horned lizard (Crother (FTHLICC 2003a, p. 10). Comments and materials received, as et al. 2008, p. 35). A home range is the area in which an well as supporting documentation for The flat-tailed horned lizard occurs animal (as an individual) typically lives. this rulemaking is available for public within the range of the desert horned Flat-tailed horned lizards can have inspection, by appointment, during lizard (Phrynosoma platyrhinos). relatively large home ranges compared normal business hours at the U.S. Fish Additionally, Goode’s horned lizard (P. to other species of lizards of similar size and Wildlife Service, Carlsbad Fish and [platyrhinos] goodie), which Klauber (FTHLICC 2003a, p. 9). Muth and Fisher Wildlife Office, 6010 Hidden Valley (1935, p. 179) considered to be a (1992, p. 34) found the mean home Road, Suite 101, Carlsbad, CA 92011; subspecies of the desert horned lizard range size was 2.7 hectares (ha) (6.7 telephone 760–431–9440; facsimile (Klauber 1935, p. 179), also occurs acres (ac)) on the West Mesa, California. 760–431–9624. within the range of the flat-tailed In the Yuma Desert of Arizona, Young FOR FURTHER INFORMATION CONTACT: Jim horned lizard in the portion southeast of and Young (2000, p. 54) found mean Bartel, Field Supervisor, Carlsbad Fish the confluence of the Gila and Colorado home ranges for males differed between and Wildlife Office (see ADDRESSES Rivers (Mulcahy et al. 2006, p. 1823). drought and wet years, while those of section). If you use a Recent genetic analyses support Goode’s females did not. The mean home range telecommunications device for the deaf horned lizard as a differentiable size for males was 2.5 ha (6.2 ac) during (TDD), call the Federal Information evolutionary species (Mulcahy et al. a dry year versus 10.3 ha (25.5 ac) Relay Service (FIRS) at 800–877–8339. 2006, pp. 1807–1826). Hybrids between during a wet year. Female mean home SUPPLEMENTARY INFORMATION: flat-tailed and Goode’s horned lizards, ranges were smaller at 1.3 ha (3.2 ac) exhibiting a mix of morphological and and 1.9 ha (4.7 ac) in dry and wet years, Background genetic characters, have been observed respectively (Young and Young 2000, p. The flat-tailed horned lizard southeast of Yuma, Arizona (Mulcahy et 54). Young and Young (2000, p. 55) (Phrynosoma mcallii) is a small, spiny al. 2006, p. 1810), while apparent noted a wide variation in movement

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patterns, with a few home ranges motionless when approached (Wone northwestward continuation of the Gulf estimated at greater than 34.4 ha (85 ac). and Beauchamp 1995, p. 132); however, of California. During the period starting Flat-tailed horned lizards are not they may occasionally bury themselves at least several million years ago, as sea known to drink standing water in loose sand if it is available (Norris levels rose and fell, the Gulf of (FTHLICC 2003a, p. 8), but they 1949, p. 176), and even more rarely, flee California filled the present-day Salton apparently do rain-harvest (Grant 2005, (Young and Young 2000, p. 12). Their Trough, often extending the Gulf pp. 66–67), which is a behavior that propensity to remain motionless and northward into the present-day San some horned lizard species use to bury in the sand, along with their Gorgonio Pass, east of Cabazon, channel precipitation or condensation cryptic coloration and flattened body, California. The Colorado River flowed collected on the lizard’s body to its make them difficult to detect visually, into the Gulf at roughly the same mouth for consumption (Sherbrook which serves as a way to evade geographical area as today, but with the 2003, p. 104). Thus, nearly all of the predators but also makes them difficult Gulf extending to a more northerly water consumed by flat-tailed horned for surveyors to find in the field point, the river flowed into the Gulf lizards is from the food they eat (FTHLICC 2003a, pp. 9, 65; Grant and mid-way along its length. (preformed water) (FTHLICC 2003a, p. Doherty 2007, p. 1050) (see also The Colorado River, which originates 8; Grant 2005, pp. 66–67). Most horned ‘‘Population Dynamics’’ section, below). in the Rocky Mountains and flows lizard species, including the flat-tailed Additional life-history information is through the Grand Canyon, historically horned lizard, are ant-foraging available in the Flat-tailed Horned transported large quantities of fine- specialists (Pianka and Parker 1975, pp. Lizard Rangewide Management Strategy grained sediment. Where the river 141–162; Sherbrooke and Schwenk (FTHLICC 2003a, pp. 6–11). joined the Gulf, sediments were 2008, pp. 447–459). More than 95 deposited forming a broad delta. These Setting and Habitat percent of the diet of flat-tailed horned sediments continued to increase and lizards is composed of ants, with The flat-tailed horned lizard is created a barrier that divided the Gulf species of harvester ants (genera Messor endemic (restricted) to the Salton into a land-locked northern portion (the and Pogonomyrmex) predominating in Trough and the region north of the Gulf Trough) and a marine-linked southern most areas of the lizard’s range, but of California in northwest Sonora, portion (the Gulf). The northern portion, species of Dorymyrmex, Pheidole, and Mexico, both of which lie within the which remains below sea level but Myrmecocystus are also consumed Lower Colorado Subdivision of the without a direct connection with the (Pianka and Parker 1975, p. 148; Turner Sonoran Desert (Shreve and Wiggins ocean, eventually dried out. However, and Medica 1982, p. 820; Young and 1964, p. 6). The climatic conditions over the Colorado River continued to Young 2000, p. 38; FTHLICC 2003a, p. the range of the flat-tailed horned lizard meander across its delta and seasonal 8). are characterized by hot summer flooding promoted avulsion (i.e., Flat-tailed horned lizards, typical of temperatures, mild winter temperatures, abandonment of an old river channel reptiles, obtain their body heat from the and little rainfall. Winter rainfall and the creation of a new one). Thus, surrounding environment (ectothermic) predominates in the western portion of the river would sometimes flow into the (Mayhew 1965, p. 104; Sherbrooke the species’ range while summer rainfall Gulf and sometimes into the Trough, the 2003, pp. 75–81). To gain body heat, predominates in the eastern portion of lowest point of which—referred to as they bask in the sun, often on rocks or the species’ range (Shreve and Wiggins the Salton Basin—is about minus 84 other substrates that are warmed by 1964, pp. 17–20, 49, 50; Johnson and meters (m) elevation (277 feet (ft) below insolation. During the heat of the day, Spicer 1985, p. 14). Periods of drought sea level). to escape extreme surface temperatures, are not uncommon (Shreve and Wiggins Water from the meandering Colorado flat-tailed horned lizards may bury 1964, p. 18). River periodically filled the Salton themselves just below the surface Although the region in northwest Basin to varying depths (and areal (Norris 1949, pp. 178–179) or retreat to Sonora, Mexico, represents roughly half extent), depositing sediments in the a burrow made by other organisms of the current range of the flat-tailed process. The lake that periodically (Young and Young 2000, p. 12). Adult horned lizard, its distribution within the formed, especially in its recent but flat-tailed horned lizards are reported to Salton Trough has been more dynamic. prehistoric incarnations, is referred to be obligatory hibernators (i.e., an As discussed below, the geologic and by most authors as Lake Cahuilla. Its organism that must enter a dormant land use changes in the Salton Trough maximum depth depended on elevation period regardless of environmental have substantially shaped the status of of the delta, which is now about 12 m conditions) (Mayhew 1965, p. 103). the species today. elevation (39 ft above sea level). The Hibernation may begin as early as To better understand population Lake was full as recently as the early October and end as late as March (Muth trends of the flat-tailed horned lizard 1600s, but smaller, shallower and Fisher 1992, p. 33), although relative to the geologic setting and its manifestations were present at various individuals have been noted on the current distribution within sandy times since then (including the modern surface during January and February habitat, we are providing a summary of Salton Sea, discussed below). When (FTHLICC 2003a, p. 9). Hibernation the recent geologic history of the area in Lake Cahuilla was full, the Colorado burrows appear to be self-constructed the following paragraphs (summarized River water flowed into the Basin from (as opposed to using burrows from Parish 1914, pp. 85–114; Sykes the southeast, marked today by the constructed by other animals) and are 1914, pp. 13–20; Durham and Alison Alamo River and New River channels, typically within 10 centimeters (cm) 1960, pp. 47–91; van de Kamp 1973, pp. and exited the Basin farther west along (3.9 in) of the surface (Muth and Fisher 827–848; Waters 1983, pp. 373–387; a southerly route, marked today by the 1992, p. 33). Mayhew (1965, p. 115) Blount and Lancaster 1990, pp. 724– Rı´o Hardy channel, ultimately emptying found that the majority of lizards 728; Blount et al. 1990, pp. 15,463– into the Gulf of California. Floodwaters hibernated within 5 cm (2 in) of the 15,482; Stokes et al. 1997, pp. 63–75; and sediments also periodically flowed surface, with one as deep as 20 cm (8 Patten et al. 2003, pp. 1–6; Li et al. into Laguna Salada, in northwestern in) below the surface. 2008, pp. 182–197). Baja California, Mexico. Thus, even Flat-tailed horned lizards generally lie The Salton Trough (Trough) is a low- areas of the present-day Imperial, close to the ground and remain elevation valley that represents the Mexicali, and San Luis Valleys that

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were never or were less-frequently tailed horned lizards may occur in areas areas. Foley (2002, p. 54) found little inundated by Lake Cahuilla, were with soil substrates and plant correlation in substrate texture and regularly influenced by hydrologic associations that differ from these distribution of flat-tailed horned lizards, forces associated with the Colorado generalizations, as described below. when using three experimental River. Despite being in the middle of Flat-tailed horned lizards are also treatments consisting of sandy, rocky one of the driest deserts in North known to occur at the edges of vegetated and mixed substrates. However, Wright America, some of these areas were, at sand dunes, on barren clay soils, and and Grant (2003, p. 3) found flat-tailed least periodically, part of an intricate within sparse Atriplex spp. (saltbush) horned lizard abundance was positively water distribution system of channels, plant communities. Although Turner et correlated with percentage of sand sloughs, and lagoons. al. (1980, p. 15) suspected that these cover. Thus, flat-tailed horned lizard Water also flowed into the Trough recorded occurrences were actually habitat includes a variety of soils and from surrounding highlands, bringing individuals that had dispersed from other plant associations, but the habitat locally derived sediments with it. One more suitable habitats, Wone et al. is best characterized as sandy flats and notable inflow is marked by the present- (1991, p. 16) questioned this conclusion valleys in a creosote-white bursage plant day Whitewater River that flows into the (see also Wone and Beauchamp 1995, p. association. Basin from the north. Water from the 132; Beauchamp et al. 1998, p. 213), local sources would occasionally result suggesting instead that flat-tailed Plants and harvester ants are in standing water in the Basin, but these horned lizards regularly occupy at least important components to flat-tailed sources could not compete with the some of these areas. horned lizard habitat because they sheer volume the Colorado River Within a creosote plant community in comprise its primary food chain. Seeds periodically provided. the West Mesa area, Muth and Fisher make up the primary food of harvester After flowing into the Trough for a (1992, p. 61) found that flat-tailed ants (Johnson 2000, p. 92). The ants period of time, the Colorado River horned lizards preferred sandy often collect seeds from annual plants, would eventually meander back and substrates with white bursage and including some nonnative species once again flow into the Gulf. Over Psorothamnus emoryi (Emory dalea), (Rissing 1988, p. 362), but they also time, Lake Cahuilla would then become and avoided areas with creosote and gather seeds from perennial plants dry and the transported sediments Tiquilia plicata (fanleaf crinklemat). In (Gordon 1980, p. 72). Thus, a simplified would become exposed, with local Arizona, Rorabaugh et al. (1987, p.103) food chain for the flat-tailed horned sediment sources predominating the found flat-tailed horned lizard lizard may be described as follows: north end of the Trough, and Colorado abundance correlated with Pleuraphis Plants produce seeds, harvester ants eat River-derived sediments predominating rigida (big galleta grass) and sandy the seeds, and flat-tailed horned lizards the south end of the Trough. During dry substrates, but they suggested that the eat harvester ants. periods, the fine-grained sediments in presence of sandy substrates was more the Trough would be transported and important than grass. Range and Distribution sorted by prevailing winds. Thus, much Several researchers have investigated A species’ range is the region over of the Trough outside of those areas that the relationship between density of which it is distributed. The range of the were regularly influenced by the perennial plants and flat-tailed horned flat-tailed horned lizard includes the flooding and meandering of the lizard abundance. The observed Salton Trough and the region north of Colorado River was ultimately relationships varied among studies. For blanketed with soft, friable (crumbly) or example, Altman et al. (1980, p. ii) and the Gulf of California. In general, this arenaceous (sandy) soils. Similarly, Turner and Medica (1982, p. 815) found range includes portions of southeastern sediments deposited in the Colorado the relative abundance of flat-tailed California (eastern San Diego County, River delta and along the northeast horned lizards was significantly and central Riverside County, and shore of the Gulf of California were positively correlated with perennial southwestern Imperial County) and transported by winds where they plant density in creosote-white bursage southwestern Arizona (southwestern formed areas of soft, friable (crumbly) or plant communities (that is, horned Yuma County) in the United States, and arenaceous (sandy) soils, including the lizard abundance increased as perennial northeastern Baja California and ‘‘sand sea’’ of the Gran Desierto de Altar. plant density increased). In contrast, northwestern Sonora in Mexico (Turner As a result, typical flat-tailed horned Beauchamp et al. (1998, p. 210) found and Medica 1982, p. 815) (Figure 1). lizard habitat today includes areas of flat-tailed horned lizards to be present Within its range, the flat-tailed horned these sandy flats as well as the in higher densities in sparsely vegetated lizard is limited to areas below an upper associated valleys created by these areas with large patches of concretions elevation. Although the species has geologic events. Turner et al. (1980, p. (i.e., a volume of sedimentary rock in been recorded as high as 520 m (1,706 14) stated the best habitats are generally which a mineral cement fills the spaces ft) above sea level (Turner et al. 1980, low-relief areas with surface soils of between the sediment grains), gravel, p. 13), flat-tailed horned lizards are packed, fine sand or low-relief areas of and silt, than in areas that were sandy more commonly found below about 230 pavement (hardpan) overlain with loose, or densely vegetated. Altman et al. m (about 750 ft) in elevation (FTHLICC fine sand. However, the available (1980, p. 7) also reported finding flat- 2003a, p. 3). scientific information indicates that flat- tailed horned lizards in desert pavement BILLING CODE 4310–55–P

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BILLING CODE 4310–55–C

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Extensive manmade changes, chiefly the desert climate, inflow rates of smaller fork extending northeast for agriculture, have occurred over a drainage water have been high enough through the eastern Mexicali Valley and large portion of the land within the to maintain, and, for a time, even the San Luis Valley (Lower Colorado Salton Trough. Below we present a increase, the surface water elevation of River Valley) to Yuma. Although there summary of the history of agricultural the Salton Sea. are specimens of flat-tailed horned development in the Salton Trough Efforts to bring irrigation water to the lizards collected historically from (summarized from Furnish and Ladman region continued through the 1900s, and within the now-altered region (Funk 1975, pp. 83–107; Woerner 1989, pp. the system of irrigation canals was 1981, p. 281.1; Johnson and Spicer 109–112; Imperial Irrigation District eventually improved and expanded. In 1985, pp. 14–24), areas of agricultural [IID] 2002, pp. 3.1–66 to 3.1–77; Patten addition to the Imperial Valley, the and urban development do not et al. 2003, pp. 1–6). Coachella Canal was constructed to constitute habitat for the flat-tailed Near the start of the 20th century, a bring water to the southern Coachella horned lizard, and this continuous canal was built to import water to the Valley, allowing irrigated agriculture to swath of altered land use is no longer Salton Trough from the Colorado River. develop north of the Salton Sea. Similar occupied by flat-tailed horned lizards. The Salton Basin is below sea level and canal systems were built in Mexico, The current distribution of the flat- much of the rest of the Salton Trough is allowing agriculture to develop and tailed horned lizard is often described at a lower elevation than where the head expand in the Mexicali and San Luis within four, geographically descriptive of the canal was located. Thus, with the Valleys. Because these systems were ‘‘populations.’’ We use the term regionally abundant sunshine and river- gravity fed, the distribution canals population in this document to refer to sediment soils, the importation of water within the region were dictated by a loosely bounded, regionally by a gravity-fed system allowed elevation, which in turn, determined distributed collection of individuals of agriculture to proliferate. For example, where irrigated agricultural the same species. These four by 1904 approximately 60,700 ha development occurred. Thus, the populations are defined as: (150,000 ac) were in cultivation. majority of agricultural development (1) The Coachella Valley Population, Unlike the current canal, the original was confined within the outer-most including those individuals northwest canal was poorly designed because it (highest elevation) canals. Moreover, of the Salton Sea, California; had no headgate to regulate flows into croplands (and associated urbanization (2) The Western Population, including the canal. Prior to extensive dams on the and infrastructure) were contiguous in those individuals in the areas west of Colorado River, the river was prone to the Salton Trough region, with little to the Salton Sea and the Imperial Valley, flooding. The high waters of one such no intervening undeveloped natural California, and west of the Mexicali flood during the winter of 1904–05 areas. Additionally, smaller amounts of Valley, Baja California, Mexico; flowed into the canal. Soon, nearly the agricultural development using pumped (3) The Eastern Population, including entire Colorado River flowed through groundwater have occurred on a smaller those individuals in the areas east of the the canal, releasing water into the scale outside these areas. Salton Sea and the Imperial Valley but Salton Basin. Part of the flow followed The geographically confined west of the Colorado River; and the two historical riverbeds (the Alamo agricultural growth in the region is (4) The Southeastern Population, River and the New River) that were currently limited by the amount of including those individuals in the areas deepened and widened by the torrent. water available from the Colorado River, east of the Colorado River, extending Despite heroic efforts, the flow which is dependent on annual from Yuma south into Mexico and east continued until 1907. The Salton Basin precipitation in the Upper and Lower to the Gulf of California. filled to a depth of about 22 m (72 ft) Colorado River Basins. The amount of These current designations closely (at its deepest point) and covered about irrigation water that can be delivered to follow the description of populations 121,400 ha (300,000 ac), thus creating the Salton Trough from the Colorado discussed in our January 3, 2003, the modern Salton Sea. River is limited by interstate and analysis (68 FR 331), although in that Although the ‘‘creation’’ of the Salton international agreements (Furnish and document we used the United States- Sea is often times described as an Ladman 1975, pp. 83–107). Water Mexico border to further divide the accident, the inundation of the Salton conservation and transfer agreements populations (see Figure 1 above). Basin by water flowing from the completed in 2003 with the San Diego Additionally, these populations roughly Colorado River from 1905 to 1907 was County Water Authority, Imperial correspond to those used by Mulcahy et merely the most recent of many such Irrigation District, Metropolitan Water al. (2006, pp. 1807–1826) in their inundations over historical and District of Southern California, and analysis of flat-tailed horned lizard prehistorical times (see ‘‘Setting and Coachella Valley Water District has genetic data (see below for details). At Habitat’’ section above). Even without reduced the amount of water available the end of the Background section, the canal, the flood of 1905 may have in the Imperial Valley and some fields below, we summarize these four naturally flowed into the Basin. have been fallowed, resulting in a populations in greater detail. We also Since the formation of the modern decrease in the amount of irrigated use these four population names to Salton Sea, agricultural practices in the agriculture in this region (IID 2006, p. identify the geographical habitat they region have maintained the water levels 1). occupy. of the Salton Sea. If too much irrigation Aerial and satellite imagery (Carlsbad water is allowed to evaporate in the Fish and Wildlife Office geographic Populations and Genetics fields, salt levels, which are high in information system (GIS) files) The separation of the four populations Colorado River water, build up in the illustrates the development of active of flat-tailed horned lizards described soil, making it inhospitable for crops. To cultivation and associated urbanization above in the ‘‘Range and Distribution’’ prevent this hypersalinization of the and infrastructure extending from the section is supported by genetic data, to soils, a surplus of water is used for present-day delta of the Colorado River, varying degrees. Analyses of irrigation. The excess water drains by with a longer fork extending north- mitochondrial DNA data (Mulcahy et al. gravity from the fields through a northwest through the Mexicali and 2006, pp. 1807–1826; see also network of ditches into the Salton Sea. Imperial Valleys to the Coachella Valley Mendelson et al. 2004, pp. 1–42) and Even with the high evaporation rates in (punctuated by the Salton Sea), and a nuclear microsatellite data (Culver and

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Dee 2008, pp. 1–14) revealed significant separate population historically, but is to enhance communication and differences in the prevalence of certain one now because it was ‘‘created’’ by an cooperation, and to help develop annual alleles in flat-tailed horned lizard artificial barrier resulting from past or other work plans and reports; populations on either side of the agricultural and urban development. (4) Develop and distribute public Colorado River; that is, the Southeastern Management and Populations information and educational materials Population differs from the other three on the conservation effort; populations. These analyses also Three notable management (5) Provide ongoing review of, and showed that more gene flow has mechanisms are in place within the U.S. feedback on, the conservation effort; occurred near the Colorado River delta, portion of the flat-tailed horned lizard (6) Cooperate in development of major suggesting the shifting course of the range: the Interagency Conservation media releases and media projects; river over time in this area posed less of Agreement, which includes the Flat- (7) Keep local governments, a barrier than the more stable portions tailed Horned Lizard Rangewide communities, the conservation of the river channel farther north Management Strategy (Rangewide community, citizens, and other (Mulcahy et al. 2006, p. 1822; Culver Management Strategy); the Coachella interested and affected parties informed and Dee 2008, p. 11). Although Culver Valley Multiple Species Habitat on the status of the conservation effort, and Dee (2008, p. 10) noted genetic Conservation Plan (Coachella Valley and solicit their input on issues and variation in some individuals across the MSHCP); and the Lower Colorado River actions of concern or interest to them; Southeastern Population, they found Multi-Species Conservation Plan (Lower (8) Whenever possible, develop that flat-tailed horned lizards in Arizona Colorado MSCP). Implementation of the voluntary opportunities and incentives are ‘‘not genetically isolated from Interagency Conservation Agreement for local communities and private neighboring populations in Mexico.’’ has recently positively affected and is landowners to participate in the Thus, the flat-tailed horned lizards east anticipated to continue to positively conservation effort; and affect the status of flat-tailed horned of the Colorado River (i.e., the (9) Assist in generating the funds lizard populations in the United States Southeastern Population) may be necessary to implement the and, to a lesser extent, in Mexico. The considered one population that is conservation effort. recently permitted Coachella Valley significantly and genetically distinct The purpose of the Rangewide MSHCP is also worth noting because it from the populations west of the river Management Strategy is to provide a is a regional habitat conservation plan (i.e., the Coachella Valley, Western, and framework for conserving sufficient (HCP) developed under section 10 of the Eastern Populations). habitat to maintain several viable Act that covers the flat-tailed horned populations of the flat-tailed horned The three populations west of the lizard in the Coachella Valley, an area lizard throughout the range of the Colorado River also showed varying addressed at length in our previous species in the United States. The levels of genetic differentiation. withdrawals. Additionally, the Lower Rangewide Management Strategy was Mulcahy et al. (2006, p. 1821) noted the Colorado MSCP is also an HCP that ‘‘ developed by an interagency working Eastern Population was significantly addresses the flat-tailed horned lizard. differentiated from [the Western and group over a 2-year period. Despite Coachella Valley Populations], Interagency Conservation Agreement being a voluntary agreement, many of suggesting that there has not been and Flat-tailed Horned Lizard the measures to conserve flat-tailed substantial gene flow across the Rangewide Management Strategy horned lizards are formally incorporated Imperial Valley since the drying of Lake In June of 1997, the Service, Bureau into planning documents of Cahuilla.’’ However, the difference of Land Management (BLM), Bureau of participating agencies, such as the between the Coachella Valley and Reclamation (BOR), U.S. Marine Corps, Bureau of Land Management’s Western Populations was less U.S. Navy, Arizona Game and Fish California Desert Conservation Area pronounced. Although their difference Department, California Department of Plan. was supported by the presence of Fish and Game (CDFG), and California As part of the Interagency haplotypes unique to the Coachella Department of Parks and Recreation Conservation Agreement, agencies Valley Population (Mulcahy et al. 2006, (CDPR) entered into an Interagency delineated specific areas under their Table 1 on p. 1811, and p. 1817), the Conservation Agreement. All signatories jurisdiction as Management Areas. As of difference between the Western and agreed to: 2009, approximately 185,653 ha Coachella Valley Populations was not (1) Further develop and implement (458,759 ac) of the flat-tailed horned statistically significant (the other the objectives, strategies, and tasks of lizard habitat managed by signatories of populations had unique haplotypes, the Flat-tailed Horned Lizard the Interagency Conservation Agreement too). This lack of significant difference Rangewide Management Strategy exists within five Management Areas suggested to the authors that the [original, FTHLICC 1997, pp. 1–106; (see Table 1 below) (FTHLICC 2009, p. Coachella Valley Population ‘‘had more revised: FTHLICC 2003a, p. 104; see 10). These Management Areas include recent gene flow’’ with the Western below]; the Borrego Badlands, West Mesa, and Population (Mulcahy et al. 2006, p. (2) As needed for the conservation Yuha Desert (also referred to as the 1821). Thus, genetic data readily effort, and as available, provide program Yuha Basin) in the Western Population, support three of the four geographic personnel with facilities, equipment, the East Mesa in the Eastern Population, populations described above, but the logistical support, and access to lands and the Yuma Desert in the distinction between the Western and under their control; Southeastern Population (Figure 2). Coachella Valley Populations is weak or (3) Participate regularly in Interagency Additionally, the Ocotillo Wells State equivocal. This suggests that the Coordinating Committee and Vehicular Recreation Area (SVRA) was Coachella Valley Population was not a Management Oversight Group meetings designated as a research area.

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The five Management Areas were inholdings occur within Management Areas where residual effects would designed to include large areas of public Area boundaries. occur after all reasonable on-site land in the United States where flat- The 2003 Rangewide Management mitigation has been applied. The goal of tailed horned lizards have been found, Strategy includes measures to avoid, compensation under the Rangewide and to include most flat-tailed horned minimize, and compensate impacts to Management Strategy is to ‘‘prevent the lizard habitat identified by the FTHLICC the flat-tailed horned lizard and its net loss of [flat-tailed horned lizard] (1997, p. 35) as ‘‘key’’ areas for survival habitat from construction projects and habitat and make the net effect of a as determined in previous studies other development activities permitted project neutral or positive to [flat-tailed (Turner et al. 1980, pp. 1–47; Turner by signatory agencies. As described in horned lizards] by maintaining a habitat and Medica 1982, pp. 815–823; detail in the Rangewide Management [baseline]’’ (FTHLICC 2003a, p. 61). Rorabaugh et al. 1987, pp. 103–109). Strategy (FTHLICC 2003a, pp. 58–60), Compensation funds may be used ‘‘to Management Areas were proposed the avoidance and minimization acquire, protect, or restore [flat-tailed measures include (in part) avoidance of based on standard principles of preserve horned lizard] habitat both within and flat-tailed horned lizard Management design, utilizing the best information contiguous with [Management Areas]’’ Areas and the Research Area, project available at the time (FTHLICC 2003a, p. (FTHLICC 2003a, p. 60). Compensation 47). oversight and compliance measures, minimized project footprint, use of ratios range from one-to-one to six-to- The Management Areas were existing roads rather than creating new one (meaning, in latter ratio for delineated to include areas as large as roads, use of barrier fencing, and instance, that six acres-worth of possible, while avoiding extensive, project-specific habitat restoration. The compensation will be required for every existing and predicted management Rangewide Management Strategy one acre of impact), depending on the conflicts (such as off-highway vehicle outlines avoidance, minimization, and location and nature of the impacts (OHV) open areas). The Management mitigation measures intended to limit (FTHLICC 2003a, p. 61). Funds obtained Areas are meant to be the core areas for the impacts from permitted projects through compensation associated with maintaining self-sustaining populations within the Management Areas to a implementation of the Rangewide of flat-tailed horned lizards in the maximum of 1 percent of the total area Management Strategy are being used to United States (FTHLICC 2003a, p. 24). of each Management Area (FTHLICC consolidate land ownership within the The Management Areas constitute 2003a, pp. 24–43). Additionally, the Management Areas or to enhance flat- roughly 42 percent of the U.S. current Rangewide Management Strategy tailed horned lizard habitat (FTHLICC distribution. Although the majority of (FTHLICC 2003a, pp. 60–62) describes 2003a, p. 25; FTHLICC 2010, p. 8). The lands within each Management Area are compensation measures for projects original and current acreages of each State or federally owned, some private within and outside the Management Management Area are listed in Table 1.

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TABLE 1—AREA (HECTARES AND ACRES) OF FLAT-TAILED HORNED LIZARD MANAGEMENT AREAS OWNED BY SIGNATORIES TO THE INTERAGENCY CONSERVATION AGREEMENT IMPLEMENTING THE FLAT-TAILED HORNED LIZARD RANGEWIDE MANAGEMENT STRATEGY AND AREA OWNED BY NON-SIGNATORIES (PREDOMINANTLY PRIVATE) IN 1997 AND THROUGH 2009, PLUS AREA AND PERCENTAGE OF PROJECT-RELATED IMPACTS PERMITTED BY SIGNATORIES WITHIN EACH MANAGEMENT AREA (SOURCES: FTHLICC 1997, P. 74; FTHLICC 2003A, P. 48; FTHLICC 2009, P. 10; FTHLICC 2010, P. 8)

Percent of total Area of non- Total area area of Management Area of Area of non- signatory lands Total area of Total area of permitted for management area signatory lands signatory lands added to signatory lands management impact as of area permitted in 1997 in 1997 signatory lands in 2009 area 2009 for impact as of since 1997 2009 (percent)

Borrego Bad- 14,771 ha 2,388 ha (5,900 592 ha *(1,464 15,363 ha 17,159 ha 0 ha (0 ac) ...... 0.0 lands. (36,500 ac). ac). ac). (37,964 ac). (42,400 ac). West Mesa ...... 46,256 ha 8,822 ha 2,624 ha (6,483 48,880 ha 55,078 ha 86.77 ha 0.16 (114,300 ac). (21,800 ac). ac). (120,785 ac). (136,100 ac). (214.42 ac). Yuha Desert ...... 23,148 ha 1,214 ha (3,000 0 ha (0 ac) ...... 23,148 ha 24,362 ha 35.90 ha (88.70 0.15 (57,200 ac). ac). (57,200 ac). (60,200 ac). ac). East Mesa ...... 43,868 ha 2,792 ha (6,900 1,380 ha (3,410 45,248 ha 46,660 ha 38.40 ha (94.90 0.08 (108,400 ac). ac). ac). (111,810 ac). (115,300 ac). ac). Yuma Desert ..... 46,741 ha 6,273 ha 6,273 ha 53,014 ha 53,014 ha 10.50 ha (25.95 0.02 (115,500 ac). (15,500 ac). (15,500 ac). (131,000 ac). (131,000 ac). ac).

Total ...... 174,784 ha 21,489 ha 10,869 ha 185,653 ha 196,273 ha 171.57 ha 0.09 (431,900 ac). (53,100 ac). (26,857 ac). (458,759 ac). (485,000 ac). (423.97 ac). * Includes 350 ha (864 ac) owned by the Anza-Borrego Foundation.

Representatives from the agencies barriers, remain outstanding, the plan area boundary are not included in participating on the Rangewide committee reports that nearly all tasks, the Coachella Valley MSHCP. The Management Strategy (also known as many of which are ongoing or multi- Coachella Valley MSHCP addresses 27 the Interagency Coordinating year actions, are on schedule (FTHLICC listed and unlisted ‘‘covered species,’’ Committee) meet several times a year to 2010, pp. 21–25). Thus, despite being a including the flat-tailed horned lizard. coordinate and implement management voluntary agreement, the signatory On October 1, 2008, the Service issued actions (FTHLICC 2003a, pp. 1–104). agencies generally have been a single incidental take permit (TE– The Interagency Coordinating implementing the Interagency 104604–0) under section 10(a)(1)(B) of Committee regularly documents Conservation Agreement and associated the Act to 19 permittees under the progress made to conserve the flat-tailed Rangewide Management Strategy by Coachella Valley MSHCP for a period of horned lizard collectively or by meeting regularly, working to 75 years. Participants in the Coachella participating agencies (FTHLICC 1998, implement the measures of the Valley MSHCP include eight cities pp. 1–11; FTHLICC 1999, pp. 1–13; Rangewide Management Strategy (Cathedral City, Coachella, Indian FTHLICC 2001, pp. 1–24; FTHLICC including providing personnel, Wells, Indio, La Quinta, Palm Desert, 2003b, pp. 1–32; FTHLICC 2004, pp. 1– developing and distributing public Palm Springs, and Rancho Mirage); the 33; FTHLICC 2005, pp. 1–37; FTHLICC information, and providing ongoing County of Riverside, including the 2006, pp. 1–34; FTHLICC 2007, pp. 1– review and feedback. Riverside County Flood Control and 33; FTHLICC 2008a, pp. 1–35; FTHLICC Water Conservation District, Riverside Coachella Valley Multiple Species 2009, pp. 1–38; FTHLICC 2010, pp. 1– County Parks and Open Space District, Habitat Conservation Plan (Coachella 33). These reports document and and Riverside County Waste Valley MSHCP) summarize the progress member Management District; the Coachella agencies have made towards Our past assessments of the status of Valley Association of Governments; implementation of the Planning Actions the flat-tailed horned lizard, particularly Coachella Valley Water District; identified in Rangewide Management the 2003 withdrawal (68 FR 331), Imperial Irrigation District; California Strategy (FTHLICC 2003a, pp. 25–32). addressed the Coachella Valley in Department of Transportation; The reports indicate that progress by detail; thus, for consistency we again California State Parks; Coachella Valley signatory agencies has been made in the address the Coachella Valley here and Mountains Conservancy; and the following areas: (1) Designation of the elsewhere in this document. Since the Coachella Valley Conservation five Management Areas and the one 2003 withdrawal, and even since our Commission (the created joint powers Research Area; (2) requiring actions by June 28, 2006, withdrawal (71 FR regional authority). The Coachella permittees to follow the avoidance, 36745), we have issued an incidental Valley MSHCP was designed to minimization, and mitigation measures take permit for a large, regional HCP in establish a multiple species habitat outlined in the Rangewide Management the Coachella Valley. The Coachella conservation program that minimizes Strategy; (3) rehabilitating damaged and Valley MSHCP is a large-scale, multi- and mitigates the expected loss of degraded habitat within the jurisdictional habitat conservation plan habitat and incidental take of covered Management Areas; and (4) purchase of encompassing about 445,156 ha (1.1 species, including flat-tailed horned lands for flat-tailed horned lizard million ac) in the Coachella Valley of lizard (USFWS 2008, pp. 1–207, and conservation from willing sellers. central Riverside County. An additional Appendix A, pp. 298–328). The Although some lower priority actions 27,923 ha (69,000 ac) of Tribal Coachella Valley MSHCP is also a (tasks), such as research on natural reservation lands distributed within the ‘‘Subregional Plan’’ under the State of

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California’s Natural Community within the Coachella Valley MSHCP Management and Monitoring Programs Conservation Planning (NCCP) Act, as area, the Thousand Palms and Dos that are expected to conserve this amended. Palmas conservation areas (CVCC 2010, species in the plan area. Required The permit covers incidental take p. 13) (see also Description of Specific management activities include limiting resulting from habitat loss and ‘‘Populations’’ section below). Table 2 activities that degrade flat-tailed horned disturbance associated with urban describes the amount of flat-tailed lizard habitat, evaluation and development and other proposed horned lizard habitat conserved and management of edge effects and other covered activities. These activities identified to be conserved through impacts through adaptive management, include public and private development implementation of the Coachella Valley control of invasive species where within the plan area that require MSHCP. Additionally, plan necessary, and restoration and discretionary and ministerial actions by implementation is expected to limit permittees subject to consistency with enhancement of degraded habitat as impacts of development and other necessary according to monitoring the Coachella Valley MSHCP policies. covered activities on lands within An associated Management and results (CVAG 2007, p. 9–123). In our conservation areas but that have not yet Monitoring Program is also included in evaluation of the potential impacts of been acquired for conservation as part of the Coachella Valley MSHCP and the plan’s implementation on the flat- the Coachella Valley MSHCP reserve identifies specific management actions tailed horned lizard (USFWS 2008, p. for the conservation of the flat-tailed system. The plan also designates one 178), we concluded: ‘‘After reviewing horned lizard and its habitat. core habitat area (as used in that plan, the current status of this species, The Coachella Valley MSHCP this refers to an area that is large enough environmental baseline for the action identifies a reserve system that, upon to maintain a self-sustaining area, effects of the proposed action, and full implementation, will establish 21 population)—the Thousand Palms cumulative effects, it is the Service’s conservation areas that are either conservation area—and commits to biological opinion that the action, as establishing two more self-sustaining adjacent to each other or are linked by proposed, is not likely to jeopardize the populations in other parts of the reserve biological corridors. The acquisition continued existence of the flat-tailed system, if feasible, to benefit the flat- program for the plan’s reserve system is horned lizard. Loss of the Coachella tailed horned lizard. Because of the designed to conserve 52,484 ha (129,690 Valley population would have a distances separating appropriate parts of ac) during the first 30 years. This negligible [effect] on the status of the program is to be implemented such that the reserve system, relocation of flat- species as a whole, since it makes up acquisitions occur commensurate (in tailed horned lizards will be required to approximately 1 percent of the current ‘‘rough step’’) with impacts from urban re-establish or enhance populations in development that is covered under the suitable habitat areas that have the range of the flat-tailed horned lizard. plan. potential to, but currently do not, Persistence of the species in the Plan The flat-tailed horned lizard is now support self-sustaining populations. area is likely only with effective Plan known to occur only at two locations Additionally, the plan calls for implementation.’’

TABLE 2—AREA OF FLAT-TAILED HORNED LIZARD HABITAT CONSERVED, ANTICIPATED TO BE CONSERVED, IMPACTED, AND ANTICIPATED TO BE IMPACTED THROUGH IMPLEMENTATION OF THE COACHELLA VALLEY MSHCP

Criterion (source) Thousand Palms Dos Palmas

Flat-tailed horned lizard habitat area conserved at permit issuance in 1,318 ha (3,256 ac) 608 ha (1,503 ac) 2008 (CVAG 2007, p. 9–115). Additional flat-tailed horned lizard habitat area conserved in 2008 274 ha (678 ac) 107 ha (265 ac) (CVCC 2009, p. 79). Additional flat-tailed horned lizard habitat area conserved in 2009 8 ha (20 ac) 0 ha (0 ac) (CVCC 2010, pp. 39 & 51). Total flat-tailed horned lizard habitat area under conservation through 1,600 ha (3,954 ac) 715 ha (1,768 ac) 2009 (calculated). Total flat-tailed horned lizard habitat area expected to be conserved by 1,707 ha (4,219 ac) 2,078 ha (5,134 ac) MSHCP implementation (CVAG 2007, p. 9–115). Percent flat-tailed horned lizard habitat area conserved through 2009 94% 34% compared to amount required upon full implementation of the plan (calculated). Area of flat-tailed horned lizard habitat impacted by permitted activities 0 ha (0 ac) 0 ha (0 ac) through 2009 (CVCC 2009, p. 79; CVCC 2010, pp. 39 & 51). Area of flat-tailed horned lizard habitat anticipated to be impacted by 44 ha (108 ac) 163 ha (403 ac) permitted activities (CVAG 2007, p. 9–115). Percent flat-tailed horned lizard habitat area anticipated to be impacted 2% 7% compared to total area of flat-tailed horned lizard habitat in conserva- tion area (calculated).

Lower Colorado River Multi-Species delivery, and diversion of water; activities. We issued the 50-year permit Conservation Plan (Lower Colorado hydropower generation, marketing, and (TE–086834) on April 4, 2005. Most of River MSCP) delivery; and land management or the activities addressed by the Lower Native American Trust responsibilities Colorado MSCP are outside the range of The Lower Colorado River MSCP is a along the Lower Colorado River, to the flat-tailed horned lizard. The flat- joint effort by Federal and non-Federal address regulatory requirements under tailed horned lizard habitat contained (State, local, and private) entities with sections 7, 9, and 10 of the Act for their within the Lower Colorado River MSCP management authority for storage,

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planning area is under control of 2008b, pp. 1–38), flat-tailed horned For example, visual-and-scat survey agencies, especially the Bureau of lizard monitoring consists of two results show that flat-tailed horned Reclamation, that have agreed to surveys used in tandem: (1) Occupancy lizards occupied at least 80 percent of implement the Rangewide Management estimation surveys and (2) demographic the Management Areas in the years Strategy (USFWS 2005, p. 202). plot surveys. Occupancy estimation was surveyed, except in the West Mesa Implementation of the Lower designed to determine whether the Management Area in 2005, which had a Colorado River MSCP is expected to distribution (but not numbers of low level of survey effort that year. provide for the acquisition and long- individuals or densities) of flat-tailed Additionally, results from the 53-plot term protection of 230 acres of existing horned lizards in the management and subset with multi-year data from 2006 to flat-tailed horned lizard habitat that is research areas is stable, increasing, or 2009 suggested that the level of flat- currently unprotected. This action is decreasing. This component of the tailed horned lizard occupancy stayed compensation for anticipated impacts to monitoring was meant to detect large- about the same or may have even approximately 128 acres of flat-tailed scale changes in the status of flat-tailed increased slightly over time. Moreover, horned lizard habitat (USFWS 2005, pp. horned lizard distribution in the our analysis showed considerable 201–202). Purchase of protected habitat, Management Areas. The monitoring of support to conclude that there was no potentially near the Dos Palmas reserve demographic plots was designed to linear decline in the proportion of area, is scheduled to start in 2011 (BOR delineate flat-tailed horned lizard survey plots occupied by flat-tailed 2010, p. 274). Additionally, activities population dynamics and trends by horned lizards. These results only covered under the permit will be estimating abundance each summer and reflect the occupancy of flat-tailed designed to avoid or minimize effects to yearly survival, recruitment, and horned lizards within the areas the species and its habitat in accordance population growth rate between years. surveyed and do not necessarily reflect the conservation needs identified in the This component was meant to gather the level of occupancy throughout the Rangewide Management Strategy more in-depth information on a smaller range of the species; nevertheless, we (USFWS 2005, pp. 201–202). number of plots. However, the conclude from the above results that the We found that implementation of the demographic plots were non-randomly level of occupancy within the survey Lower Colorado River MSCP was ‘‘Not established within areas known or areas is not low, and that there is no Likely to Jeopardize the Continued suspected to support greater densities of indication of a decline. Existence of the Species’’ (USFWS 2005, flat-tailed horned lizards. The Data from the demographic plots were ‘‘ p. 202), noting The habitat area that Management Areas overall were gathered from six 9-hectare (22.2-acre) would be included [under the plan] is selected because they provided plots at the following flat-tailed horned not a significant amount of the available generally high-quality flat-tailed horned lizard Management Areas: East Mesa (1 habitat for the species. * * * Research lizard habitat. However, the use of the plot, 2007–2009), West Mesa (1 plot, and monitoring of the species within the two complementary survey types, one 2007–2009; 1 plot, 2008–2009), Yuha [Lower Colorado River MSCP] area will dispersed and coarse and the other Desert (1 plot, 2007–2009), and Yuma contribute to understanding the species, focused and narrow, allows managers to Desert (2 plots, 2008–2009). Hatchlings its distribution, and habitat needs. draw, with caution, more detailed were captured at all Management Areas * * * [and] There are not likely to be conclusions about an entire except East Mesa (which was surveyed any adverse effects to the species’ Management Area than they could have prior to the time that flat-tailed horned conservation elsewhere in the range lizards eggs would have been likely to otherwise done by interpreting just one from the issuance of an incidental take have hatched), indicating that flat-tailed of the survey types alone. Below we permit for the [Lower Colorado River horned lizards were reproducing. The summarize the information available MSCP]’’ (USFWS 2005, p. 202). presence of hatchlings during 2008, and from these monitoring efforts (source: especially 2009, suggested that Population Dynamics USFWS 2010a, pp. 1–76). reproductive conditions were favorable Flat-tailed horned lizards are difficult Occupancy surveys were conducted at in those years. to detect, which limits the effectiveness West Mesa (2005 and 2009), East Mesa Because of the complexities of of surveys for the species (FTHLICC (2006), Yuha Desert (2008), and Ocotillo analyzing a cryptic species, we used two 2003a, pp. 9, 65; Grant and Doherty Wells State Vehicular Recreation Area methodologies to calculate flat-tailed 2007, p. 1050). As a result, not only is (SVRA) (2006–2009). Separate horned lizard abundance. Because the presence and especially absence occupancy analyses of these areas were surveyed plots were not closed difficult to determine, but determining conducted based on three survey (meaning flat-tailed horned lizards the size, trend, and demography of methodologies: visual observations of could move in and out of the areas being populations is problematic as well. The flat-tailed horned lizards, lizard scat surveyed), we used two different history of flat-tailed horned lizard observations, and a combination of methods (calculations) to estimate the monitoring and the shortcomings of the visual and scat observations. Multi-year ‘‘effective survey area’’ so that we could techniques used are described in the analyses also were conducted for a translate abundance (number of Rangewide Management Strategy subset of 53 plots in Ocotillo Wells individuals) into densities (number of (FTHLICC 2003a, p. 64) and our 2003 SVRA that were surveyed annually from individuals per unit area). Using the withdrawal document (68 FR 332–333). 2006 to 2009. Our analysis indicates the first method (using a mean maximum Monitoring using more rigorous data combined visual-and-scat surveys were distance moved buffer strip to estimate collection and analytical methodologies the most likely to correctly yield a effective survey area), the density of has been conducted as part of the statistically significant result (i.e., this adult flat-tailed horned lizards ranged implementation of the Rangewide survey methodology had the greatest from 0.3 to 3.3 individuals per ha (0.1 Management Strategy (FTHLICC 2003a, statistical power). Although there are no to 1.3 individuals per ac), while the pp. 64–66; FTHLICC 2008b, pp. 1–38). comparable historical data with which second method (using a hierarchical, The results from this monitoring effort to provide context, our analysis suggests spatially indexed capture-recapture are described below. that the level of occupancy of flat-tailed model to estimate effective survey area) As detailed in the Flat-tailed Horned horned lizards within the surveyed yielded a range from 0.7 to 4.4 Lizard Monitoring Plan (FTHLICC areas seemed relatively high at all sites. individuals per ha (0.3 to 1.8

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individuals per ac). The results from the not declined since 2007, and probably the northeast shore of the Salton Sea second method are likely to be more not declined since 1997. (Turner and Medica 1982, p. 817; realistic because they incorporated FTHLICC 2003a, pp. 2–6; CVCC 2010, p. Description of Specific ‘‘Populations’’ additional spatial information. 13). The Dos Palmas population is small Other estimates of density of flat- As stated earlier, we have divided the and likely isolated from other tailed horned lizards are available in the current range of the flat-tailed horned populations because of the presence of scientific literature, but comparisons lizard into four populations based on the Salton Sea to the west; canals, roads between and among the different studies geographic locales. The 2003 Rangewide and urban and agricultural development (including the recent monitoring) are Management Strategy includes a GIS- to the northwest; and canals, roads and confounded by differing survey and based map (FTHLICC 2003a, p. 5) of the urban and agricultural development to analysis methodologies. Nevertheless, ‘‘current distribution’’ of the flat-tailed the southeast. However, not all of these the above densities at the three horned lizard. Except for the Coachella barriers are likely to completely restrict California Management Areas were Valley Population, where the flat-tailed flat-tailed horned lizard movement (see generally within the range of estimates horned lizard is now limited to two the Factor E discussion, below). The reported by Grant (2005, pp. 39–40) occurrences, we used the GIS data as a genetic affinities of the Dos Palmas during 2002–2004. Similarly, the basis for our assessment of the population are not known. densities of adult flat-tailed horned distribution of flat-tailed horned lizard Geographically, the flat-tailed horned lizards at the Yuma Desert Management populations. A summary of these lizards at Dos Palmas Preserve could Area reported above were generally populations is presented below. arguably be considered part of either the similar to the ranges of estimates Coachella Valley Population Western Population or Eastern ‘‘ ’’ presented by Young and Young (2000, (California)—The current distribution Population (see below); however, p. 28) during 1997–1998, Young et al. within the Coachella Valley as defined because the true affinities of this by the Rangewide Management Strategy (2004b, p. i) during 2003, and Young population are not known, and because (FTHLICC 2003a, pp. 3–5) does not and Royle (2006, p. 9) in 2005. the Dos Palmas reserve area is covered represent the best scientific distribution Comparisons to even earlier estimations under the Coachella Valley MSHCP and information available for this region. of flat-tailed horned lizard densities, its associated monitoring and Urban and agricultural development has although even more tenuous because of management, herein we consider the continued in the Coachella Valley, and differing methodologies, are also within Dos Palmas flat-tailed horned lizards to there are many areas of unsuitable or similar ranges. Despite similar ranges in be part of the Coachella Valley degraded habitat. In addition to areas of densities reported from the various Population. The area of flat-tailed unsuitable habitat, many of which serve studies through time, the increased horned lizard habitat in the Coachella statistical and methodological rigor of as a barrier to flat-tailed horned lizard movement, other potential manmade Valley Population is about 3,785 ha recent efforts has reduced the level of (9,353 ac) (see Table 2). uncertainty in the results. Thus, these barriers exist, including several major recent density estimates are an highways, a railway, and canals. The Western Population (California and improvement over older estimates. only area within the Coachella Valley Baja California)—This population The available data indicate that flat- proper that is now known to be includes flat-tailed horned lizards in the tailed horned lizard abundances and occupied by flat-tailed horned lizards is areas west of the Salton Sea, the densities have remained relatively in the Thousand Palms reserve (CVCC Imperial Valley, and the Mexicali stable from 2007 to 2009; however, with 2010, p. 13). Other areas of potentially Valley. Using a GIS-based assessment to only 3 years of standardized monitoring, suitable habitat occur in the region, estimate the area of this portion of the these data cannot yet provide including areas that were formerly ‘‘current distribution’’ as defined by the meaningful inferences about long-term known to be occupied (Barrows et al. Rangewide Management Strategy trends. Additionally, no abundance or 2008, p. 1891), although recent surveys (FTHLICC 2003a, pp. 3–5), we estimated density information is available for the have not detected any flat-tailed horned that the Western Population occupies lower-quality habitat areas outside the lizards (CVCC 2010, p. 13). Thus, the 341,989 ha (845,073 ac). Of this acreage, demographic plots. However, the ‘‘current distribution’’ as defined by the approximately 253,020 ha (625,226 ac) complementary coarse-scale occupancy Rangewide Management Strategy is within the United States. Within the survey data mentioned above suggests (FTHLICC 2003a, pp. 3–5) does not U.S. portion of the Western Population, flat-tailed horned lizards are widely accurately reflect the area occupied by approximately 48,262 ha (119,258 ac), distributed spatially and, in at least at flat-tailed horned lizards in the or about 19 percent, is non-Federal or one Management Area, temporally Coachella Valley; as such, we do not use non-State owned, or is more likely to be consistent. This conclusion suggests a GIS-based assessment for the developed. The habitat within this area that flat-tailed horned lizard population Coachella Valley as we do for the other is mostly intact except for a few trends in the surveyed lower-quality geographical ‘‘populations.’’ developed areas, but as discussed in the habitat areas are not dissimilar to those The Coachella Valley MSHCP is the ‘‘Barriers and Small Populations’’ of the surveyed higher-quality habitat primary driver of monitoring and section under Factor E, potential areas. Moreover, because the recent management activities for the Coachella manmade barriers to flat-tailed horned (2007–2009) and older (1997–2005) Valley Population of the flat-tailed lizard movement (in addition to areas of density estimates are all generally horned lizard because the Rangewide urban and agricultural development) within similar ranges, this suggests the Management Strategy does not include include Interstate 8; State Routes 78, 86, overall density of flat-tailed horned any Management Areas in this region. and 98; two railways; the fence and lizards within the surveyed The Coachella Valley Population area is other activities along the international Management Areas has not markedly the smallest of the four geographic border in the United States, and Mexico decreased over the past decade or so. ‘‘populations,’’ and we primarily Federal Highway 2 in Mexico. The Thus, with the previously mentioned identify it as a separate population to be Rangewide Management Strategy caveats in mind, we conclude that flat- consistent with our past analyses. Flat- designates three Management Areas in tailed horned lizard populations in the tailed horned lizards also occur in the this population area, including Borrego Management Areas are not low and have vicinity of the Dos Palmas Preserve near Badlands, West Mesa, and Yuha Desert

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(see Table 1), and a research area at the flat-tailed horned lizard movement (in Southeastern Population is 1,073,551 ha Ocotillo Wells SVRA. Much of the addition to areas of urban and (2,652,802 ac), by far the largest of the westernmost portion of this population agricultural development) include four population areas. Of this acreage, is within Anza-Borrego Desert State Interstate 8, State Routes 78 and 98, the approximately 67,922 ha (167,839 ac) is Park. Additionally, private lands are All-American Canal and the Coachella within the United States. Within the scattered throughout the U.S. portion, Canal, and the international border U.S. portion of the Southeastern with large aggregations in the Borrego fence in the United States (see ‘‘Barriers Population, approximately 5,158 ha Springs area and in the vicinity of (but and Small Populations’’ section under (12,746 ac), or about 8 percent, is outside of) Ocotillo Wells SVRA. The Factor E, below). The Rangewide privately owned; an additional 5,832 ha range of the flat-tailed horned lizard in Management Strategy designated the (14,411 ac), or about 9 percent, is State this population also extends southward East Mesa Management Area within the of Arizona-owned lands. The habitat into Mexico, crossing the international area occupied by the Eastern Population within the Southeastern Population area border at the Yuha Desert and (see Table 1). The geographic extent of is mostly intact except for a few continuing south along the east side of the Eastern Population also includes the developed areas, but potential barriers the Peninsular Ranges and west of Algodones Dunes (also known as the to flat-tailed horned lizard movement Laguna Salada in Baja California Imperial Sand Dunes or Glamis Sand (in addition to areas of urban and (FTHLICC 2003a, pp. 2–5). The status of Dunes), a portion of which is designated agricultural development) include the population in this portion of the Wilderness, and a narrow strip of Interstate 8 and the Yuma Areas Service range in Mexico is poorly known, but habitat south of the international border Highway in the United States; the there have been few substantive changes at the southern edge of the Algodones international border (combined with to the landscape in this area. Dunes (FTHLICC 2003a, pp. 2–5). The Mexico Federal Highway 2); Mexico Additionally, flat-tailed horned lizards portion of the Eastern Population area in Federal Highway 8; and a railway in were observed recently near Cerro Mexico is bound by agricultural Mexico (see ‘‘Barriers and Small Prieto, Baja California, which is east of development (unsuitable habitat) on the Populations’’ section under Factor E, the Sierra de Los Cucapahs (Sierra west, south, and east. The status of the below). Cucapa´) and west of the agricultural portion of the Eastern Population in In summary, using a GIS-based areas of the Mexicali Valley (A. Calvo Mexico is poorly known, but flat-tailed assessment to estimate the size of the Fonseca, Pronatura Noroeste, in litt. horned lizards were observed recently current distribution of the flat-tailed 2010). This recent detection is outside in this area (A. Calvo Fonseca, in litt. horned lizard as defined by the of the current distribution as depicted in 2010). Rangewide Management Strategy the Rangewide Management Strategy Southeastern Population (Arizona and (FTHLICC 2003a, p. 5), we estimated (FTHLICC 2003a, p. 5). Sonora)—This population includes flat- that the three population areas tailed horned lizards in the areas east of (excluding the Coachella Valley Eastern Population (California and the Colorado River, extending from Population) comprise roughly 1,585,000 Baja California)—This population Yuma, Arizona, south and east to the ha (3,916,600 ac), of which includes flat-tailed horned lizards in the Gulf of California in northwestern approximately 467,000 ha (1,154,000 ac) areas east of the Salton Sea and the Mexico. In Arizona, the flat-tailed (less than 30 percent) is within the Imperial Valley but west of the Colorado horned lizard occurs in Yuma County, United States and approximately River. While the isolated population at ranging over the Yuma Desert south of 1,100,000 ha (2,718,000 ac) (more than Dos Palmas Preserve could be included the Gila River and west of the Gila and 70 percent) is within Mexico. The area as part of either the Eastern Population Butler Mountains (Rorabaugh et al. of flat-tailed horned lizard habitat or the Coachella Valley Population 1987, p. 104; FTHLICC 2003a, pp. 2–6). occupied or likely to be occupied that based on its geographic location, for the The Rangewide Management Strategy already is or is expected to be conserved purposes of our analysis of threats to the designated the Yuma Desert in the Coachella Valley Population is species we consider the Dos Palmas Management Area within the area about 3,785 ha (9,353 ac) (see Table 2). Preserve population to be part of the occupied by the Southeastern Previous Federal Actions Coachella Valley Population because of Population (see Table 1). In Mexico, the the similarity of potential threats when flat-tailed horned lizard ranges from the In 1982, we first identified the flat- compared to the populations in the international border in the Yuma Desert tailed horned lizard as a category 2 Coachella Valley, and its inclusion south and east through the Pinacate candidate species for listing under the within the Coachella Valley MSHCP Region to the sandy plains around Act (47 FR 58454; December 30, 1982). plan area. Using a GIS-based assessment Puerto Pen˜ asco and Bahia de San Jorge Category 2 candidate species were ‘‘taxa to estimate the area of the Eastern along the Gulf of California (Johnson for which information now in Population portion of the ‘‘current and Spicer 1985, p. 13; Gonza´les- possession of the Service indicates that distribution’’ (as defined by the Romero and Alvarez-Cardenas 1989, p. proposing to list the species as Rangewide Management Strategy 519; FTHLICC 2003a, pp. 2–5). About 60 Endangered or Threatened is possibly (FTHLICC 2003a, pp. 3–5)), we percent of the flat-tailed horned lizard appropriate, but for which sufficient estimated that the Eastern Population habitat in Sonora lies within two data on are not currently available to occupies 169,617 ha (419,133 ac). Of Mexican Federal natural protected biologically support a proposed rule’’ this acreage, approximately 146,121 ha areas: the Upper Gulf of California and (47 FR 58454). We again identified the (361,073 ac) is within the United States. Colorado Delta Biosphere Reserve, and flat-tailed horned lizard as a category 2 Within the U.S. portion of the Eastern the Pinacate and Gran Desierto de Altar candidate species in our 1985 notice of Population, approximately 5,844 ha Biosphere Reserve (CEDO 2001, p. 3). review (50 FR 37958; September 18, (14,441 ac), or about 4 percent, is non- Using a GIS-based assessment to 1985). In 1989, we elevated the species Federal or non-State owned, or is more estimate the area of this portion of the to category 1 status (54 FR 554; January likely to be developed. The area ‘‘current distribution’’ as defined by the 6, 1989). Category 1 included species occupied by the Eastern Population is Rangewide Management Strategy ‘‘for which the Service currently has mostly intact except for a few developed (FTHLICC 2003a, pp. 3–5), we estimated substantial information on hand to areas, but potential manmade barriers to that the area occupied by the support the biological appropriateness

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of proposing to list as endangered or to take voluntary steps aimed at 1993, proposed rule to list the flat-tailed threatened’’ (54 FR 554). We maintained ‘‘reducing threats to the species, horned lizard as a threatened species the category 1 status for the flat-tailed stabilizing the species’ populations, and (68 FR 331). The Service found the horned lizard in our 1991 notice of maintaining its ecosystem’’ (see lizard to be ‘‘in danger of extirpation in review (56 FR 58804; November 21, FTHLICC 2003a, p. 80). the Coachella Valley’’ (68 FR 348); 1991). On July 15, 1997, we issued a final however, we determined that the On November 29, 1993, we published decision to withdraw the proposed rule Coachella Valley is not a significant in the Federal Register a proposed rule to list the flat-tailed horned lizard as a portion of the species’ range. We to list the flat-tailed horned lizard as a threatened species (62 FR 37852). We concluded in the January 3, 2003, threatened species under the Act (58 FR based the withdrawal on three factors: withdrawal that the flat-tailed horned 62624). On February 22, 1994 (59 FR (1) Population trend data did not lizard populations on either side of the 8450), we published a notice reopening conclusively demonstrate significant Imperial Valley-Salton Sea and in the public comment period and population declines; (2) Some of the Arizona were not likely to become announcing that we had scheduled a threats to the flat-tailed horned lizard endangered in the foreseeable future public hearing on March 22, 1994, in habitat had abated since the proposed and that listing the species was not Imperial, California, in response to a rule was issued; and (3) Our conclusion warranted. request from the public. Our November that the recently approved Interagency The Tucson Herpetological Society 15, 1994, candidate notice of review Conservation Agreement would ensure and others filed a complaint with the stated that we had proposed to list the further reductions in threats (62 FR District Court for the District of Arizona species as threatened (59 FR 58982). 37852). challenging the January 3, 2003, Subsequently, the passage of Public On December 30, 1997, the Defenders withdrawal of the proposed rule. In a Law 104–6, 109 Stat. 73 on April 10, of Wildlife and others filed a complaint ruling issued on August 30, 2005, the 1995, resulted in a delay in our final in the U.S. District Court for the District Court for the District of Arizona listing determination for the flat-tailed Southern District of California issued an order granting plaintiffs’ horned lizard. Although the statute’s challenging our 1997 withdrawal of the motion for summary judgment, citing primary purpose was to provide proposed rule. On June 16, 1999, the our failure to specifically evaluate the additional funds for overseas military District Court upheld our decision to lost habitat of the flat-tailed horned operations, it also included a rider that withdraw the proposed listing rule. The lizard, and whether the amount of lost withdrew funding for listing District Court’s decision was appealed habitat represented a significant portion determinations. Through a series of and on July 31, 2001, the Ninth Circuit of the species’ range. On December 7, moratoria, funding restrictions, and Court of Appeals vacated the previous 2005, we published a document in the continuing resolutions, this restriction ruling of the District Court. The case Federal Register reinstating the 1993 in use of funds remained in effect until was remanded back to the Secretary proposed rule (70 FR 72776). On March April 26, 1996, when the Omnibus because: (1) The withdrawal of the 2, 2006, we announced in the Federal Appropriations Act was enacted (Pub. L. proposed rule did not expressly Register that we were reopening the 104–134, 110 Stat. 1321, (1996)), which consider whether the flat-tailed horned public comment period on the 1993 contained a moratorium on certain lizard is likely to become an endangered proposed rule for 14 days for the listing activities but allowed the species within the foreseeable future in purpose of soliciting comments and President to waive the moratorium. On a significant portion of its range; and (2) information relevant to the specific April 26, 1996, President Clinton The withdrawal of the proposed rule issue identified in the District Court’s suspended the provision limiting did not ‘‘address the lizard’s viability in November 2005 ruling (i.e., whether the implementation of Section 4 of the Act a site-specific manner with regard to the flat-tailed horned lizard’s lost historical (61 FR 24667; May 16, 1996). Earlier in putative benefits of the Interagency habitat rendered the species likely to 1996, our notice of review had indicated Conservation Agreement.’’ In become in danger of extinction in the that we had proposed to list the species accordance with the Appeals Court’s foreseeable future throughout all or a as threatened (61 FR 7596; February 28, ruling, we published a document in the significant portion of its range) (71 FR 1996). Federal Register on December 26, 2001, 10631). On April 21, 2006, we On January 21, 1997, the Bureau of reinstating the 1993 proposed rule and announced in the Federal Register an Land Management (BLM) announced in opening a 120-day public comment additional public comment period on the Federal Register that the draft Flat- period (66 FR 66384). the 1993 proposed rule from April 21, tailed Horned Lizard Rangewide On May 30, 2002, we published a 2006, to May 8, 2006 (71 FR 20637). Management Strategy was available for document in the Federal Register After re-examining the lost historical public comment (62 FR 3052). On May reopening the public comment period habitat of the flat-tailed horned lizard in 16, 1997, in response to a lawsuit filed for an additional 60 days (67 FR 37752) relation to our January 3, 2003, by the Defenders of Wildlife and other and announced that we would be withdrawal, we determined that the lost plaintiffs to compel us to make a final holding public hearings in El Centro, historical habitat is not a significant listing determination on the flat-tailed California, on June 19, 2002. On portion of the species’ range, and its loss horned lizard, the District Court in September 24, 2002, we published in does not result in the species likely Arizona ordered us to issue a final the Federal Register another document becoming endangered in the foreseeable listing decision within 60 days. In June (67 FR 59809) announcing the future throughout all or a significant 1997, several State and Federal reopening of the public comment period portion of its range. We published our agencies, including the Service, signed for an additional 15 days to allow for decision in the Federal Register on June an Interagency Conservation Agreement peer review, additional public comment 28, 2006, to once again withdraw the committing to implement the recently on the proposed rule, and submittal of November 29, 1993, proposed rule to finalized Flat-tailed Horned Lizard information that became available since list the flat-tailed horned lizard as a Rangewide Management Strategy our 1997 withdrawal. threatened species (71 FR 36745). (FTHLICC 1997, pp. 1–106). Pursuant to On January 3, 2003, we again Following a supplemental complaint the Interagency Conservation published in the Federal Register a from Tucson Herpetological Society and Agreement, cooperating parties agreed decision to withdraw the November 29, others challenging the 2006 withdrawal

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of the proposed rule to list the flat-tailed withdrawing the proposed rule (71 FR areas and did not constitute a significant horned lizard under the Act, the United 36745) did not address the five factors threat to the species. However, we did States District Court for the District of in detail because its scope was limited state that past agricultural, urban, and Arizona (the District Court) granted by a court order (see Previous Federal associated infrastructural development summary judgment in favor of the Actions section). In this document, we (such as canals and roads) had Secretary of the Interior (Tuscon use the best scientific and commercial fragmented the species’ range, which we Herpetological Society v. Kempthorne, data available to evaluate current discuss below as a separate threat under 04–CV–00075–PHX–NVW); however, potential threats to flat-tailed horned Factor A. this ruling was appealed to the Court of lizard and its habitat rangewide per the Fragmentation and Past Habitat Loss Appeals for the Ninth Circuit. In a five listing factors, and we provide brief ruling issued on May 18, 2009, the summaries of the 1993 and 2003 Because of our past treatment of Court of Appeals for the Ninth Circuit evaluations for context. fragmentation in our previous rules, we reversed the District Court’s ruling are providing a discussion of A. The Present or Threatened when it determined that in the context fragmentation as a term and its Destruction, Modification, or of the analysis of whether the lizard’s application to the five-factor analysis for Curtailment of Its Habitat or Range lost historical range constituted a the flat-tailed horned lizard. This significant portion of the species’ range, For this factor, we evaluated the discussion should: (1) Provide a clear the administrative record did not present (current) or threatened definition of the term that we use in this support what the Court of Appeals for (anticipated) impacts that may be document, and (2) acknowledge that our the Ninth Circuit viewed as the affecting the habitat or range of the flat- lack of clarity for this term in past Service’s conclusion that flat-tailed tailed horned lizard. This factor does documents may have resulted in horned lizard populations were stable not address historical or past actions unanswered questions as to how the and viable throughout most of its that resulted in destruction, flat-tailed horned lizard may have been current range. modification, or curtailment of the affected by historical development in On November 3, 2009, the District species’ habitat or range. Past actions the Salton Trough. Because of the Court remanded the 2006 withdrawal to that destroyed, modified, or curtailed connection between fragmentation and the Service for further consideration and the species’ habitat or range are not historical habitat loss, we also describe reinstated the 1993 proposal to list the threats in and of themselves. Any how historical habitat loss was species. The District Court ordered the persisting ramifications of such past addressed in past assessments. Service to complete this reconsideration actions that may be threats to the In the 2003 withdrawal document, we in accordance with the deadlines set species are addressed under Factor E defined fragmentation as the ‘‘breaking forth in 16 U.S.C. 1533(b). On March 2, (other natural or manmade threats), up of a habitat or ecosystem into smaller 2010, we published a notice in the below. However, for Factor A, we do parcels’’ (68 FR 341). This definition is Federal Register announcing the look to past actions to inform our similar to the more detailed version reinstatement of the 1993 proposed rule, evaluation of potential future threats used by Wilcove et al. (1986, p. 237) the reopening of the public comment affecting the species’ habitat or range in who defined habitat fragmentation as period for 60 days, and the scheduling that the history of past actions allows us occurring ‘‘when a large expanse of of public hearings (75 FR 9377). Public to predict the likelihood of such actions habitat is transformed into a number of hearings were held in Palm Desert, continuing into the foreseeable future. smaller patches of smaller total area, California, on March 23, 2010, and In the 1993 proposed rule (58 FR isolated from each other by a matrix of Yuma, Arizona, on March 24, 2010. 62625–62626), we identified historical habitats unlike the original.’’ Thus, flat-tailed horned lizard habitat losses fragmentation is a process, one that Summary of Factors Affecting the that resulted in the curtailment of the inextricably involves habitat loss Species species’ range under Factor A. We noted (Fahrig 1999, p. 87). However, in Section 4 of the Act (16 U.S.C. 1531 threats that were current or anticipated addition to the effects associated with et seq.) and the regulations that at that time, including agricultural and habitat loss, fragmentation also includes implement the listing provisions of the urban development, off-highway vehicle the effects associated with the fractured Act (50 CFR part 424) set forth the (OHV) use, geothermal energy nature of that habitat after its procedures for adding species to the development, sand and gravel extraction transformation (Fahrig 2003, p. 487). Federal Lists of Endangered and operations, military training activities, The implication is that the biological Threatened Wildlife and Plants. A and construction of roads and utility properties of the remaining, small, species may be determined to be an corridors. We also mentioned that flat- isolated patches of habitat have changed endangered or threatened species due to tailed horned lizard habitat had been during or as a result of the one or more of the five factors described fragmented, causing isolation of fragmentation of the habitat (van den in section 4(a)(1) of the Act (Factors A populations (curtailment of the species’ Berg et al. 2001, p. 225). In other words, through E). range) (see below for additional after some portion of the habitat of a We evaluated threats to the flat-tailed discussion on fragmentation). species has been destroyed, that species horned lizard under the five listing Additionally, the 1993 proposed rule may be impacted by one or more factors in the 1993 proposed rule to list also mentioned gold mining as a secondary effects (threats) associated the flat-tailed horned lizard as potential threat. There are currently no with reduction in the size of remaining threatened under the Act (58 FR 62624). gold mines in flat-tailed horned lizard habitat patches (or the populations of Subsequent documents in 1997 and habitat, and we are not aware of any the species therein) and the isolation of 2003 withdrawing the proposed rule to proposals for new gold mines; therefore, those patches (and populations) from list the species included additional we do not expect gold mines to become each other (Andre´n 1994, p. 355). Thus, evaluations (62 FR 37852; 68 FR 331). a threat in the foreseeable future. the effects of fragmentation include: (1) The 2003 document withdrawing the In the 2003 withdrawal document (68 The effects associated with the ongoing proposed rule was the most FR 341–345), we found that current and loss of habitat; and (2) the subsequent, comprehensive and the most recent five- anticipated urban and agricultural secondary effects that are the current factor analysis. The 2006 document development was limited to a few, small ramifications of past habitat loss.

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Because multiple secondary effects may information on the genetics of flat-tailed agree with the conclusions of previous be related or correlated to each other horned lizard populations raises further assessments, both by us and by others, (Fahrig 2003, pp. 491–492), the term doubts about the validity of the that portions of the Coachella, Imperial, fragmentation, as it has been used in the assumptions made in earlier Mexicali, Yuma, and San Luis Valleys scientific literature and by the Service assessments, both by us and by others, once provided suitable areas of flat- in past assessments of this species, is of historical flat-tailed horned lizard tailed horned lizard habitat. We also ambiguous (Haila 2002, p. 321). Because habitat. agree that historical agricultural of this ambiguity, in applying the Act’s As discussed above (see Background development (and, to a lesser extent, five listing factors to the flat-tailed section), genetic data readily support urban development) destroyed large horned lizard, we will address current three of the four geographic populations areas with flat-tailed horned lizard and anticipated habitat loss under as distinct, indicating that these habitat, thus curtailing the size of the Factor A, and the relevant, identifiable populations generally had little genetic Coachella Valley, Western, Eastern, and secondary effects (including threats interchange among each other (Mulcahy Southeastern flat-tailed horned lizard associated with fragmentation) to the et al. 2006, pp. 1807–1826; Culver and populations in both the United States species under Factor E. Dee 2008, pp. 1–14). This lack of genetic and Mexico. However, the effects of past Our past assessments describe in exchange suggests a barrier separated, actions are better addressed under detail and attempted to quantify the and likely still separates, these Factor E. historical development in the Salton populations. As discussed in the In the sections below, we address the Trough (58 FR 62626; 62 FR 37857; 68 Background section, the areas within present or threatened destruction, FR 341–345; 71 FR 36751), as did the the present-day Imperial Valley, modification, or curtailment of the scientific literature (such as Johnson Mexicali Valley, and San Luis Valley habitat or range of the flat-tailed horned and Spicer 1985, p. 38, 45–48; were historically interlaced by a lizard. We evaluate the current and Rorabaugh et al. 1987, p. 106; Hodges network of Colorado River-influenced anticipated effects associated with 1995, pp. 1–18; Hodges 1997, pp. 1–16; water courses, including the Alamo several types of land development, the Piest and Knowels 2002, pp. 1–4; River, the New River, and the Rı´o Hardy invasion of nonnative plants, OHV FTHLICC 2003a, pp. 2–3; Piest and (or their precursors or equivalents). activity, and military training. We first Knowels 2006, pp. 1–4). These Historically, these ‘‘rivers’’ were describe the respective threats in documents have, to a greater or lesser dependent upon the Colorado River for general terms and then assess those extent, estimated the areal extent of water and only transported water threats to the habitat or range of the flat- current and historical flat-tailed horned periodically. Prior to the increase of tailed horned lizard, focusing on lizard habitat in all or certain portions agricultural development and prior to subareas (such as identified populations of its range. One of the more detailed of the digging of the irrigation canal and or Management Areas) within the such analyses was Hodges (1997, pp. subsequent flood that created the Salton species’ range, where appropriate. 15–16), who concluded that 503,161 ha Sea early in the 20th century (see Development (1,243,341 ac) out of 979,016 ha Background section), some areas along (2,419,200 ac), or about 51 percent, of these river channels were characterized We define development as flat-tailed horned lizard habitat in the by Parish (1914, p. 88) as having commercial and residential United States had been destroyed by ‘‘channels, sloughs, and lagoons.’’ These development (i.e., urban development), past development. hydrologically influenced areas likely and the conversion of land for any However, such calculations, no matter did not contain flat-tailed horned lizard agricultural purpose. Such development how carefully crafted, are necessarily habitat, as defined in the Background not only includes the obvious associated based on assumptions of what areas section. As such, not all of the area infrastructure (e.g., roads, pipelines, constituted historical habitat for the between the present-day Salton Sea and canals, and power lines), but also species (such as Hodges 1997, p. 10). the Gulf of California, including areas reservoirs, power generation facilities, Because much of the area within the outside the lakebed of historical Lake and resource extraction operations such range of the flat-tailed horned lizard was Cahuilla, historically supported flat- as drilling and mining. converted to agricultural and urban tailed horned lizard habitat. This For the purpose of evaluating the development during the early half of the information further supports our threats to a species and its habitat, we 20th century (see Background section, conclusion presented in our 2006 focus on the developmental activities above) prior to any systematic surveys withdrawal that the ‘‘area of the that threaten to convert land from a for the flat-tailed horned lizard, little historical range periodically inundated natural or undeveloped state to land no reliable information exists on the by Lake Cahuilla was not important to longer suitable as habitat for the species. historical distribution of the species the long-term viability of the flat-tailed We consider both the direct and, where (Barrows et al. 2008, p. 1886). horned lizard because this area was appropriate (within the context of We questioned the validity of such frequently unavailable and likely Factor A), the indirect effects of such assumptions in our past assessments. contained little quality habitat’’ (71 FR developmental activities. While land For example, Hodges (1997, pp. 5, 7, 36750). development typically has a similar and 16) included the area now Because of the extensive manmade effect, that is the destruction or inundated by Salton Sea as historical changes to the landscape, we cannot modification of habitat, differing land habitat, but we stated in our 2003 precisely determine with any degree of uses resulting from development withdrawal that the Salton Sea area specificity how much of the area was activities can lead to different indirect could arguably be considered ephemeral historically flat-tailed horned lizard effects. We therefore distinguish among historical habitat. In our 2006 habitat. Moreover, we maintain that the types of development when withdrawal, we concluded that the much uncertainty exists with any evaluating the effects of such former lakebed of historical Lake attempt to precisely quantify the development on a species or its habitat. Cahuilla (including and beyond the amount of flat-tailed horned lizard For this evaluation of flat-tailed present-day Salton Sea) likely was not habitat that has been destroyed by horned lizard under Factor A, we habitat important to the flat-tailed historical agricultural development, as determine whether development is a horned lizard (71 FR 36750–36751). The has been attempted in the past. We current or anticipated threat to flat-

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tailed horned lizard habitat. Below, we Biosfera El Pinacate y Gran Desierto de historic past. Many of the urban centers address agricultural and urban Altar) (CEDO 2001, p. 3), where in the region that serve agricultural development, as well as development agricultural development is limited by communities are contained within associated with energy generation Mexican law. agricultural areas. While urbanization projects. Agricultural activities outside of the has continued as the human population areas receiving Colorado River water are Agricultural Development within the region has grown (FTHLICC severely restricted by the climate of the 2003a, p. 12; Indrelunas 2010, pp. 1–3), Within the dry Colorado Desert, Salton Trough region, including in most of this urban development agricultural activity is substantially Mexico. Thus, while recent agricultural associated with these urban centers has dependent upon irrigation water development destroyed areas of flat- come at the expense of former imported from the Colorado River. As tailed horned lizard habitat in the croplands. As such, this development is discussed in the Background section, Southeastern Population, the overall not currently destroying substantial most of the agricultural development acreages were small, especially amounts of available flat-tailed horned within the range of the flat-tailed compared to the amount of habitat lizard habitat (FTHLICC 2003a, p. 12). horned lizard occurred early in the 20th available in the Southeastern However, certain areas of urban century. Because Colorado River water Population. development not associated with active is a finite resource, agricultural Agricultural development, most of or past agriculture have resulted in the development is no longer expanding which occurred between 1945 and the destruction of flat-tailed horned lizard into new areas and destroying flat-tailed 1980s (Mills 2009, p. 28), occurred in habitat. This impact is most evident in horned lizard habitat to any substantial the Borrego Springs area of the habitat the Coachella Valley where urban degree. Information available from the occupied by the Western Population. development not associated with Coachella Valley Water District (CVWD The Borrego Springs area uses a local agricultural communities continues 2002, p. 1; 2003, p. 1; 2004, p. 1; 2005, aquifer for irrigation, and the area does today (Indrelunas 2010, pp. 1–3). This p. 25; 2006, p. 27; 2007, p. 25; 2008, p. not receive Colorado River water; growth is corroborated by the number of 25; 2009, p. 25) indicates a slight however, the aquifer is overdrawn domestic water meter services, which decline in the amount of irrigable acres (County of San Diego 2008, p. 8; Mills grew by over 25 percent from 2001 to and a fairly steady though variable 2009, p. 4). We do not anticipate 2008 (CVWD 2002, p. 1; 2003, p. 1; amount of water delivered from 2001 to substantial amounts of agriculture to 2004, p. 1; 2005, p. 25; 2006, p. 27; 2008, indicating that new agricultural expand into adjoining natural lands in 2007, p. 25; 2008, p. 25; 2009, p. 25). development has not occurred in the this area (see Mills 2009, pp. 40–42). This urban growth is occurring in the Coachella Valley within the past decade Moreover, the area of private lands in surrounding desert areas, which likely or so. Also, fields are being fallowed in the Borrego Valley is constrained within include flat-tailed horned lizard habitat. the Imperial Valley because less water is Anza-Borrego Desert State Park. As a Our interpretation of past and recent available for irrigation in this area (IID result, we believe that agricultural aerial imagery supports this trend. 2006, p. 1). Thus, conversion of land for development no longer threatens flat- agriculture is no longer considered a tailed horned lizard habitat in the The flat-tailed horned lizard now threat to flat-tailed horned lizard habitat Borrego Springs portion of the Western appears to be restricted to two in the Coachella Valley and in the Population, nor will it in the foreseeable occurrences within the Coachella Valley Imperial Valley portions of the Western future. MSHCP plan area, the Thousand Palms and Eastern Populations, and is not In conclusion, the available conservation area and the Dos Palmas considered to be a threat in the information indicates that the vast conservation area (CVCC 2010, p. 13). foreseeable future. majority of the agricultural development The Coachella Valley MSHCP includes In contrast, recent agricultural within the range of the flat-tailed numerous measures to minimize and development has destroyed flat-tailed horned lizard took place in the mitigate impacts of urban development horned lizard habitat in other areas. historical past and only a small amount on the flat-tailed horned lizard (see Between 2002 and 2006, an unreported of development has been documented in Coachella Valley Multiple Species but minority fraction of 1,534 ha (3,790 recent times. Because conversion of Habitat Conservation Plan (Coachella ac) of flat-tailed horned lizard habitat land to agriculture in the region is Valley MSHCP) section above for a was developed for agricultural use in limited by the availability of irrigation detailed discussion). Approximately 94 Arizona (Piest and Knowles 2006, p. 1). water and that water is limited, we do percent of the potential habitat where Rodriguez (2002, p. 21) also recorded not expect agriculture to expand flat-tailed horned lizards are known to recent agricultural development in significantly into adjoining flat-tailed occur in the Thousand Palms Mexico; however, the majority of the horned lizard habitat in the future. conservation area is land that is already agricultural development in the Moreover, increased demand for water protected (Table 2), including about 62 Mexicali and San Luis Valleys occurred outside the region has resulted in a percent that is part of the Coachella in the early to mid-20th century, closely decreased amount of Colorado River Valley National Wildlife Refuge. following the historical agricultural water available for agriculture in the Similarly, approximately 34 percent of development north of the border Imperial Valley, which has resulted in the habitat at Dos Palmas is protected (Furnish and Ladman 1975, pp. 84–88). the fallowing of fields in this area. (Table 2). The high level of protection Additionally, about 60 percent of the Therefore, we conclude that agricultural of flat-tailed horned lizard habitat at the flat-tailed horned lizard habitat in development is not a substantial threat Thousand Palms conservation area Mexico lies within two Mexican Federal to the flat-tailed horned lizard translates into a low magnitude of threat natural protected areas, the Upper Gulf throughout its range, nor is it from urban development at this of California and Colorado Delta anticipated to be in the foreseeable location. In contrast, because only about Biosphere Reserve (la Reserva de la future. one-third of the flat-tailed horned lizard Biosfera del Alto Golfo de California y habitat at the Dos Palmas conservation Delta del Rı´o Colorado), and the Urban Development area is currently in protected status, the Pinacate and Gran Desierto de Altar Like agricultural development, urban potential magnitude of urban Biosphere Reserve (la Reserva de la development largely occurred in the development at the latter location is

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greater. However, because this area of such, we expect the amount of impact Salada, we believe urban development habitat is farther away from existing from urban development on areas of in this area is likely similarly limited by urban areas, the immediacy of the threat flat-tailed horned lizard habitat owned available resources and isolation. Thus, of urban development is likely lower, by the State of California and the we conclude that urban development is even without the protections for flat- Federal government in the Western and not a threat to the species in the tailed horned lizard included in the Eastern Population to be small now and Western Population, nor is it likely to Coachella Valley MSHCP plan (which within the foreseeable future because become a threat in the foreseeable requires the protection of the Dos little urban development is likely on future. Palmas conservation area). Therefore, State Park lands and most military As discussed above, we expect the overall threat from urban lands, and what development that may impacts from urban development on development of flat-tailed horned lizard occur on Federal lands will be Federal lands in the Eastern Population habitat in the Coachella Valley minimized through implementation of to be limited. Moreover, the designation Population is low. the Rangewide Management Strategy, of the East Mesa Management Area Most of the area occupied by the U.S. including through implementation of offers protective mechanisms for 45,248 portion of the Western Population of the CDCA Plan on BLM lands. ha (111,810 ac) (Table 1), or about 27 flat-tailed horned lizards is owned by Moreover, the designation of the percent of the Eastern Population, of the State of California (more than 27 Borrego Badlands, West Mesa, and Yuha flat-tailed horned lizard habitat within percent) or by the Federal government Desert Management Areas offer this population. Impacts from permittee actions are limited to 1 percent of the (more than 52 percent), and the vast protective mechanisms for 96,599 ha majority of the U.S. portion of the area within each Management Area (238,700 ac) (Table 1) of flat-tailed Eastern Population is federally owned (FTHLICC 2003a, p. 33). Additionally, horned lizard habitat within this (more than 95 percent). Much of the 10,654 ha (26,327 ac), or about 6 percent population. Impacts from permittee State of California land in the Western of the Eastern Population, is designated actions are limited to 1 percent of the Population is administered by California as a Wilderness Area where urban area within Management Areas State Parks, including Anza-Borrego development is prohibited. Most urban (FTHLICC 2003a, p. 33). As described Desert State Park and Ocotillo Wells development occurs on private above, we expect minimal or no urban State Vehicular Recreation Area. We do property, and less than 5 percent of the development on Federal and California not expect any substantive urban U.S. portion of the Eastern Population State lands within the area occupied by development activities on State Park- area occurs on private property. Limited administered lands. However, such the Western Population and Eastern water and isolation of the private lands development, should it occur, would Population, but urban development may likely prevent any substantive urban likely follow the avoidance, occur within private lands. Although development in the region, including minimization, and compensation private inholdings are scattered the small amount of habitat in Mexico. measures of the Rangewide Management throughout the Federal and State lands Thus, we conclude that urban Strategy because California State Parks in the region, few concentrations of development is not a threat to the is a signatory agency to the Interagency private land exist. The largest species in the Eastern Population, nor is Conservation Agreement. concentration of private inholdings it likely to become a threat in the Additionally, much of the Federal within the areas occupied by the foreseeable future. land is administered by the BLM, which Western Population occurs in and Urban development has occurred is a signatory to the Interagency around the community of Borrego recently in the Southeastern Population Conservation Agreement. Moreover, the Springs, California. Urban development of flat-tailed horned lizards. Areas of BLM has incorporated the Rangewide in this area is limited to a finite area recent urbanization include Management Strategy into the California within the Borrego Springs area, which development near the communities of Desert Conservation Area (CDCA) Plan is an area of private lands completely Yuma, Arizona (Piest and Knowles under the Federal Land Policy and surrounded by Anza-Borrego Desert 2006, p. 1); San Luis Rı´o Colorado, Management Act of 1976 (43 U.S.C. State Park. Additionally, development Sonora, Mexico (Rodriguez 2002, p. 23); 1701 et seq.) (FLPMA). The CDCA Plan in this area may be further restricted by and Puerto Pen˜ asco, Sonora, Mexico directs BLM’s permitting of a limitation in the amount of available (Rodriguez 2002, p. 23). Most (about 84 development projects on the lands the groundwater (Mills 2009, p. 4). As we percent) of the flat-tailed horned lizard plan covers, including the U.S. portions concluded in 2003 (68 FR 342), even if habitat in Arizona is federally owned, of the Western and Eastern Populations. urban development continues, this area where urban development is less likely, Thus, the avoidance, minimization, and is small enough that it is unlikely that and most of the U.S. Federal land in the compensation measures in the the combined urban or agricultural Southeastern Population is within the Rangewide Management Strategy are development in or around this 53,014-ha (131,000-ac) Yuma Desert implemented by BLM on these lands, geographically limited area poses a Management Area (Table 1), where which reduces the impact such significant threat to the flat-tailed impacts from permittee actions are development to flat-tailed horned lizard horned lizard throughout its range. limited to 1 percent of the area habitat. Other federally owned lands in Moreover, limited water and isolation of (FTHLICC 2003a, p. 26). Additionally, these areas are lands owned by the the remaining private lands scattered avoidance and minimization measures Navy, which is also a signatory to the within the public lands likely will are in place within the Barry M. Interagency Conservation Agreement. prevent any large-scale urban Goldwater Range, Arizona, to prevent or Not only do we anticipate that the development in the region, further limit impact to the flat-tailed horned Navy’s participation in the Rangewide reducing the effects that urbanization lizard and its habitat from military Management Strategy will continue, may have on the Western Population of development (USFWS 1996, pp. 18 and which will limit the amount of impact the flat-tailed horned lizard. Because the 58). Nevertheless, development impacts to flat-tailed horned lizard habitat, but Mexican portion of the Western may occur. For example, construction the Navy’s use of these lands, largely as Population is isolated from other by Marine Corps Airs Station, Yuma, of bombing ranges, will result in little inhabited areas by the Sierra de Los a new aircraft landing field and urban development on these lands. As Cucapahs and the dry lakebed of Laguna associated infrastructure for the F–35B

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Joint Strike Fighter at the Barry M. all of the flat-tailed horned lizard proposals not only include geothermal Goldwater Range is expected to habitat in the Thousand Palms reserve facilities, but also projects harnessing permanently remove 33.5 ha (82.7 ac) of is already protected, most of the Dos solar radiation and wind. Examples of flat-tailed horned lizard habitat, plus Palmas reserve is not (see Table 2). recent proposals that may affect flat- have additional long-term adverse Implementation of the Coachella Valley tailed horned lizard habitat include the effects on a 17.8 ha (44 ac) (USFWS MSHCP is expected to limit the impacts following: geothermal projects near the 2010b, p. 46). Even so, this project to the flat-tailed horned lizard and its Superstition Mountains (Navy 2008, pp. includes minimization measures called habitat (USFWS 2008, Appendix A, p. 1–40) and the Truckhaven area west of for by Rangewide Management Strategy, 317). Furthermore, in our evaluation of Salton City (BLM 2007a, pp. 1–3), solar thereby reducing the impact of this the potential impacts of the plan’s projects near Plaster City (BLM and CEC development to the species and its implementation on the flat-tailed 2010, p. ES–1), and a wind project west habitat (USFWS 2010b, pp. 10–12, 45). horned lizard (USFWS 2008, p. 178), we of the community of Ocotillo (Ocotillo Thus, we conclude that urban concluded: ‘‘After reviewing the current Express 2009, p. 1). Because the development in Arizona is not a status of this species, environmental development of energy generation significant threat to the species, nor is baseline for the action area, effects of facilities occurs within the range of the it likely to become a threat in the the proposed action, and cumulative flat-tailed horned lizard habitat, we foreseeable future. effects, it is the Service’s biological assess the magnitude of this In Mexico, urban development is opinion that the action, as proposed, is development to the species below. likely within the foreseeable future not likely to jeopardize the continued Similar to other forms of around San Luis Rı´o Colorado, Puerto existence of the flat-tailed horned lizard. development, energy generation projects Pen˜ asco, and elsewhere along the Gulf Loss of the Coachella Valley population may result in destruction or of California coast. Despite an increase would have a negligible [effect] on the modification of flat-tailed horned lizard in accessibility to remote areas (Bu´ rquez status of the species as a whole, since habitat. These projects can include and Martı´nez-Yrı´zar 1997, p. 390), the it makes up approximately 1 percent of buildings, roads, power lines, and vast majority of the habitat for the the current range of the flat-tailed pipelines, although they differ in the Southeastern Population in Mexico horned lizard. Persistence of the species details. For example, geothermal plants remains isolated with respect to urban in the Plan area is likely only with typically include wells and pipelines development, because urban effective Plan implementation.’’ Because (often aboveground), solar plants development requires access to other of the limited amount of private land, typically include solar collecting arrays resources, which are not necessarily urban development is also only likely to (using various technologies to convert available with mere physical access. destroy relatively small amounts of flat- solar energy to electrical energy), and Moreover, compared to the 1,005,630 ha tailed horned lizard habitat in the wind farms have lines or arrays of wind (2,484,966 ac) of flat-tailed horned Western, Southeastern, and Eastern turbines. lizard habitat in the Mexican portion of Populations. Additionally, in areas of The total acreage of potential the Southeastern Population, roughly 60 flat-tailed horned lizard habitat in the development for renewable energy percent of which lies within two United States and Mexico where facilities is small compared to the Mexican Federal natural protected areas urbanization has the potential to occur, overall range of the species. For where development is limited (CEDO it is likely that the amount of urban example, in California, the BLM 2001, p. 3), we expect the amount of development will be limited by the maintains a GIS database of rights-of- urban development to be relatively availability of water and the isolated way applications for energy generation small. Thus, we conclude that urban nature of many of these areas. The facilities. Additional permits are needed development is not a significant threat implementation of the Rangewide before the potential facilities listed in to the species in the Mexican portion of Management Strategy further restricts the database can be built, and even if the Southeastern Population, nor is it development in the United States, they obtain all of the necessary permits, likely to become a threat in the limiting impacts inside designated flat- it is not guaranteed that all of them will foreseeable future. tailed horned lizard Management Areas be built. Moreover, some of these right- Therefore, despite some urban to 1 percent of the area. In Mexico, of-way applications have been rejected, development occurring in the urban development is likely to be denied, or withdrawn. However, Southeastern Population, we believe limited within the Federal natural assuming that the facilities in the BLM that this development is small relative protected areas (Rodriguez 2002, p. 25). database are built, the total area of to the overall amount of flat-tailed Therefore, we conclude that urban development on BLM land for all of the horned lizard habitat in the development is not a significant threat applications on file as of December 2010 Southeastern Population and is unlikely to flat-tailed horned lizard habitat would be about 2,585 ha (6,387 ac) in to significantly increase in the throughout its range, nor is it the Eastern Population, and 18,841 ha foreseeable future; thus, this anticipated to become a significant (46,556 ac) in the Western Population. development does not pose a substantial threat in the foreseeable future. The BLM data only include areas of threat to the species in the Southeastern BLM (Federal) land and do not include Population, nor is it likely to become a Energy Generation Facility Development what, if any, nearby private land that threat in the foreseeable future. The analyses in the 1993 proposed may also be developed as part of these In conclusion, flat-tailed horned rule and 2003 withdrawal document energy projects. We do not have data for lizard habitat has been lost to urban both identified development of the potential impacts to private lands development in the Coachella Valley, geothermal energy facilities as a adjacent to these areas, but we made a and we expect urbanization to continue potential threat to flat-tailed horned rough assessment of the adjacent private there. The available information lizard habitat. Since then, increased land that may potentially be included in indicates the distribution of the species interest in renewable forms of electrical these projects which may add about 260 in the Coachella Valley is now limited generation has resulted in a greater ha (about 640 ac) to the impacts in the to two occurrences that are within two number of proposed energy Eastern Population and about 10,600 ha Coachella Valley MSHCP conservation development facilities and their (about 26,000 ac) to the impacts in the areas (CVCC 2010, p. 8); although nearly associated infrastructure. Recent Western Population. Using these values,

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the energy development in the Eastern percent. As of 2009, signatory agencies energy development projects in that Population may impact roughly 2,845 control approximately 196,273 ha country is likely to be small relative to ha (7,030 ac) of BLM and private lands, (485,000 ac) of flat-tailed horned lizard the total amount of habitat. Therefore, which is about 1.7 percent of the habitat in the designated Management we anticipate the development of energy Eastern Population area, and the energy Areas and have collectively permitted generation facilities does not now nor in development in the Western Population activities on 171.57 ha (423.97 ac), or the foreseeable future pose a significant may impact roughly 29,441 ha (72,750 0.09 percent (Table 1). Thus far, threat to flat-tailed horned lizard and its ac) of BLM and private lands, which is signatory agencies have consistently habitat. about 8.6 percent of the Western implemented the Rangewide Invasive, Nonnative Plants Population area. Combined, these Management Strategy, even in projects—assuming that they are all permitting development electrical In our 2003 withdrawal document, we built, which is not likely—would generation facilities. Moreover, the included the effects of invasive, impact a total of about 2 percent of the implementation of the Rangewide nonnative plants as a potential threat to nearly 1.6 million ha (3.9 million ac) of Management Strategy is not completely flat-tailed horned lizard habitat (68 FR the total range of the species (using 2003 voluntary at this point; aspects of the 345). However, we concluded that ‘‘current distribution’’). Rangewide Management Strategy have nonnative plants did not pose a Although we expect additional energy been incorporated into documents that substantial threat because of the limited development facilities may be implement regulatory mechanisms, extent to which such plants had constructed elsewhere within the range including the Federal Land Policy and established themselves in flat-tailed of the species, including in Arizona and Management Act (43 U.S.C.1701 et seq.) horned lizard habitat (68 FR 345). The Mexico, we are not aware of any specific (FLPMA), which affects development on available literature also suggests proposals that are as large as those BLM lands (see Factor D). Many of the invasive, nonnative plants are a proposed in California. Therefore, we anticipated energy development potential threat to flat-tailed horned conclude that the total acreage of facilities are on BLM lands or otherwise lizard habitat (such as Hodges 1997, pp. potential development for renewable would require easements or access 4, 5, and 9; CEDO 2001, p. 2; FTHLICC energy facilities is small compared to across BLM lands; thus, the 2003a, pp. 18–19; Hammerson et al. the overall range of the species. development of these energy generation 2007, p. 4), but specifics on how Additionally, on lands managed by facilities would be subject to the nonnative species are impacting flat- tailed horned lizard habitat are signatory agencies to the Interagency provisions of the Rangewide generally lacking. Conservation Agreement, we expect the Management Strategy through The perennial nonnative tree, impacts to flat-tailed horned lizard implementation of FLPMA. habitat (whether inside or outside of Tamarix aphylla (athel pine), has been designated Management Areas) will be In sum, the overall acreage of planted as a windbreak in the Coachella further reduced because of the potential impacts from development of Valley. This tree can reduce or prevent avoidance, minimization, and energy facilities is likely to be small wind-transport of sand, thereby compensation measures of the compared to the total range of the reducing available flat-tailed horned Rangewide Management Strategy. species, including private lands likely to lizard habitat there (England 1983, p. Moreover, because of the avoidance be developed. Moreover, because of the 152). Although T. aphylla typically and minimization measures, including prevalence of Federal and State lands in spreads vegetatively by adventitious the 1-percent impact limit in flat-tailed the U.S. portions of the range of the flat- roots or submerged stems, the species horned lizard Management Areas, most tailed horned lizard and because most of can spread sexually by seed following of the energy generation facilities have this land is managed by signatories to flood events (Walker et al. 2006, pp. been proposed outside of the the Interagency Conservation Agreement 191–201). While perhaps not as invasive Management Areas, although some implementing the Rangewide as other species of Tamarix (Cal–IPC impacts to Management Areas are Management Strategy, we expect that 2003, p. 4), T. aphylla trees have been anticipated resulting from related the vast majority of proposed energy removed in some Coachella Valley infrastructure development (FTHLICC/ development projects that are likely to MSHCP reserve areas in the Coachella MOG 2010, p. 2). For example, the affect flat-tailed horned lizard habitat in Valley as management to improve 2,454–ha (6,063–ac) Imperial Valley the United States will be subject to the habitat (FTHLICC 1999, p. 4). Moreover, Solar project site is proposed outside of avoidance, minimization, and the population of flat-tailed horned the flat-tailed horned lizard compensation measures incorporated lizards in the Coachella Valley proper is Management Areas called for by the into the Rangewide Management now found only in the Thousand Palms Rangewide Management Strategy, but an Strategy, including in areas outside of reserve area (CVCC 2010, p. 8), where associated transmission line is expected designated Management Areas. The the plan’s habitat management is to run for about 12 kilometers (km) (7.5 signatories to the Interagency focused. Therefore, we do not consider miles (mi)) within the Yuha Desert Conservation Agreement have been T. aphylla to be an invasive, nonnative Management Area. However, this actively implementing the Rangewide species that is threatening flat-tailed proposed transmission line was routed Management Strategy since its horned lizard habitat. along an existing powerline corridor to inception, and have committed to its Nonnative annual plants, such as minimize effects to flat-tailed horned continued implementation. Brassica tournefortii (Saharan mustard), lizard habitat in the Management Area Additionally, the Rangewide Schismus barbatus (common (BLM and CEC 2010, pp. B.1–18, C.2– Management Strategy has been Mediterranean grass), and Salsola kali 9, and C.2–42). incorporated into the CDCA Plan, which (Russian thistle), can blanket certain While project sites may be proposed means it will be implemented as a areas of the Colorado Desert in years within flat-tailed horned lizard regulatory mechanism (as opposed to a with higher amounts of rainfall (Brown Management Areas, the Rangewide voluntary agreement). Although the and Minnich 1986, pp. 411–422; Lovich Management Strategy limits the total Rangewide Management Strategy is not and Bainbridge 1999, p. 318; FTHLICC acreage of impacts for a given in effect in Mexico, the amount of 2003a, p. 18; Yurkowsky 2005, in litt., Management Area to no more than 1 habitat that is likely to be destroyed by Anza-Borrego Desert State Park; Barrows

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et al. 2009, pp. 673–686). Such horned lizard typically take a long time Another potential threat to the flat- nonnative plants may adversely affect to recover after a fire (O’Leary and tailed horned lizard that may arise from flat-tailed horned lizard habitat Minnich 1981, pp. 61–66; Brown and a change in plant species composition throughout its range by altering fire Minnich 1986, p. 411; Brooks and Esque after a fire is that harvester ants, the regimes (Brown and Minnich 1986, pp. 2002, p. 330). Thus, fire can change the primary food of the flat-tailed horned 418–421; Brooks and Esque 2002, pp. species composition of the perennial lizard, could be affected. Fire likely kills 334–336); stabilizing Aeolian soils (i.e., and annual plant communities. individual harvester ants on the surface soil that is transported from one place Moreover, provided enough water at the time of the fire, but evidence to another by wind; Barrows et al. 2009, (rainfall) is available, annual plants, suggests the underground colonies p. 684); changing plant assemblages especially nonnative species, proliferate survive (Zimmer and Parmenter 1998, p. (Barrows et al. 2009, p. 683); and after a fire (Minnich 1994, p. 104), 282; Underwood and Christian 2009, p. changing the availability of seeds for which may provide additional fuel and 325). As described in the Background harvester ants, the primary food source promote additional wildfires. Plant section, harvester ants eat seeds of for the flat-tailed horned lizard (Gordon communities in areas with recurrent annual and perennial plant species. 1980, p. 70). Dense stands of plants, fires may convert from vegetation types Although changes in plant composition which are typical of invasive, nonnative dominated by native shrubs into types may alter the type and quantities of plant species in years of higher amounts dominated by nonnative annual grasses available seeds consumed by ants, ant of rainfall, also may challenge the and forbs (type conversion) (Brown and forage likely will not be eliminated, and locomotor abilities of the wide-bodied Minnich 1986, p. 411). Type conversion may even increase because of the flat-tailed horned lizard (Newbold 2005, appears to be occurring near the highly increase in annual plants (Zimmer and p. 17). urbanized areas, such as the Coachella Parmenter 1998, p. 282; Underwood and Plant growth will vary annually in the Valley (Brown and Minnich 1986, p. Christian 2009, p. 325). For example, Colorado Desert because of the variable 411), where increased human activity several of the species found by Gordon amount and timing of rainfall that the offers higher numbers of ignition (1980, p. 72) to be important to region receives. Moreover, annual plants sources (Brooks and Esque 2002, p. harvester ants were also species of die by the end of spring, and in the 337), but not in the more remote areas plants found by Brown and Minnich harsh desert climate the amount of of flat-tailed horned lizard habitat. (1986, p. 416) to do well after a fire. standing biomass of the annual plants, Moreover, the amount of rainfall is a Therefore, wildland fire does not appear once dead, quickly decreases (Barrows critical factor in how much plant growth to pose a threat to harvester ants. et al. 2009, p. 684). We expect the occurs (Barrows et al. 2009, p. 673). The In conclusion, the spread of invasive, amount and timing of rainfall within the amount of rainfall is unpredictable nonnative plants does not appear to be range of the species will continue to be within the range of the flat-tailed a significant threat to flat-tailed horned variable into the foreseeable future, even horned lizard, and is likely to be so for lizard habitat throughout its range at with the potential effects of climate the foreseeable future. It is not clear this time, nor is it likely to become a change (Field et al. 1999, pp. 8–10). As how the fire regime will be affected long significant threat in the foreseeable a result, the effects of invasive, term, but in the foreseeable future, future. nonnative plants are generally short- wildland fire does not appear to be a Off-Highway Vehicles (OHVs) lived in areas of flat-tailed horned lizard threat. habitat (Barrows et al. 2009, p. 673), and The analyses in the 1993 proposed because of the likelihood of continued Additionally, it is unclear whether rule and 2003 withdrawal document variability in precipitation, we expect this localized change in vegetation included OHV activity as a potential the potential effects of invasive, affects the specific habitat components threat to the flat-tailed horned lizard. nonnative plants to continue to be short- upon which flat-tailed horned lizards The Rangewide Management Strategy lived into the foreseeable future. With rely. For example, flat-tailed horned also describes off-highway (OHV) or off- the potential exception of increased lizards take refuge under perennial road vehicle activity as a potential occurrence of wildland fires, we do not shrubs for shade and to avoid predators threat (FTHLICC 2003a, pp. 12–14). We believe that the growth of invasive, (Muth and Fisher 1992, pp. 1–77; consider OHVs to be all vehicles used nonnative plants poses a lasting, Sherbrooke 2002, pp. 109–120). Fire off-road, including, but not limited to, significant threat to flat-tailed horned typically kills the existing desert shrubs, automobiles, dune buggies, motorcycles, lizard habitat now or in the foreseeable but shrubs do regrow after a fire, all-terrain-cycles, four-wheelers, and future. We examine the potential threat although the plant species composition military vehicles. OHV activity of wildland fire below. is likely to have changed (Brown and includes, but is not limited to, Fires typically are rare events in the Minnich 1986, pp. 411). Thus, during recreational, military, law-enforcement western Sonoran Desert because of the the period of time following fire while (such as Border Patrol), and trans-border natural ‘‘limited biomass, wide spacing shrubs are regrowing, flat-tailed horned trafficking activities. As discussed in the between shrubs and sparse ground lizards will have fewer options for Background section, flat-tailed horned cover’’ (Brown and Minnich 1986, p. thermoregulation and predator lizard habitat typically consists of sandy 411). However, the periodic increase in avoidance. While this condition is not flats and valleys occupied by plant the amount of available fuel from permanent, it remains unclear if the species that are typical of the creosote- nonnative, annual plants in years of change in plant species composition white bursage plant association. The heavy precipitation has allowed the will have a lasting effect on the flat- presence of ants as a food source is also frequency, size, and intensity of fires in tailed horned lizard, especially if type important. desert plant communities to increase conversion were to occur. Nonetheless, OHV activity may modify flat-tailed (Brown and Minnich 1986, p. 411; because this change in plant species horned lizard habitat because of impacts Brooks and Berry 2006, pp. 117–118; composition is localized, we conclude to vegetation (Luckenbach 1975, p. 4; Trader et al. 2006, p. 314; see also any potential effects are low in Vollmer et al. 1976, p. 115; Bury et al. Rorabaugh 2010, p. 191). Moreover, magnitude at the species level, likely 1977, p. 7; Lathrop 1983, p. 164; many of the native perennial plants temporary, and thus not a significant Luckenbach and Bury 1983, p. 280; within the range of the flat-tailed threat to the species. Groom et al. 2007, p. 133), soil

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disturbance (Luckenbach 1975, p. 4;, Research in the Ocotillo Wells SVRA context of the range of the species, we Bury et al. 1977, pp. 16–18;, Webb 1983, found flat-tailed horned lizards at assumed an area of high impact from pp. 51–79), and introduction of higher densities in non-sandy habitats border-related OHV activity to be within nonnative plants (Brooks and Lair 2005, than sandy habitats within the SVRA, a 1-km (0.6-mi)-wide zone north of the p. 8). Additionally, some but not all which differed from most other research border. We estimate that the total area areas with high OHV activity have been findings (Beauchamp et al. 1998, pp. of flat-tailed horned lizard habitat shown to have fewer harvester ant 213–214). However, it was unclear if within that ‘‘zone’’ is about 12,662 ha colonies (McGrann et al. 2006, p. 77). flat-tailed horned lizards were found in (31,288 ac), or about 0.8 percent of the Past studies of OHV impacts on these atypical habitat types because they range of the species, comprising 2,318 lizards (Busack and Bury 1974, p. 182; are more variable in habitat use than ha (5,728 ac), 5,012 ha (12,385 ac), and Bury et al. 1977, p. 10; Luckenbach and previously thought, because these 5,332 ha (13,176 ac) of the Western, Bury 1983, p. 273; Klinger et al. 1990, habitat types are more available in the Eastern, and Southeastern Populations, pp. 1–17; Beauchamp et al. 1998, p. 214; Ocotillo Wells SVRA than other areas in or about 0.7 percent, 3 percent, and 0.5 Gardner 2002, p. 14; Wright and Grant which flat-tailed horned lizards have percent of those populations, 2003, p. 30) have been largely been studied, or as a response to OHV respectively. This zone of assumed high inconclusive or cannot be readily activity (Beauchamp et al. 1998, p. 214). activity is a broad-brush assessment (for applied across the range of the flat- OHV activity occurs in the Western, example, the All-American Canal runs tailed horned lizard (that is, they have Eastern, and Southeastern Populations, along the border in the Eastern but the amount (intensity, frequency) of limited ‘‘inference space’’ (Ratti and Population, likely confining any border- OHV activity varies across the Garton 1994, pp. 1–23)). Luckenbach related OHV activities in certain areas to landscape, with greater amounts of and Bury (1983, p. 278) reported that a less than 1 km (0.6 mi)). Nevertheless, activity in areas designated for OHV use pronounced reduction in flat-tailed the zone is small compared to the range and areas near existing roads, and lesser horned lizard abundance around the of the species and the three populations, amounts in areas where OHV use is not Algodones Dunes had been anecdotally individually. Moreover, since 2008, the permitted or areas that are away from noted by scientists. Marked declines in U.S. Customs and Border Protection easy access. In the Coachella Valley, herbaceous and perennial plants, constructed the ‘‘border fence,’’ which is OHV activity is expected to be arthropods, lizards, and mammals in a vehicle and, in some areas, pedestrian controlled in protected habitat areas barrier, plus associated infrastructure, in OHV-used areas compared with nearby through implementation of the control areas were also reported by certain areas between the United States Coachella Valley MSHCP (CVAG 2007, and Mexico. Although some areas of the Luckenbach and Bury (1983, p. 265). pp. 9–117) and OHV activity is not The declines, however, were for the border are not fenced, the areas of flat- identified as a conservation issue in the tailed horned lizard habitat along the Colorado Desert fringe-toed lizard (Uma annual report for 2009 (CVCC 2010, p. notata) and beetles, and did not include border are fenced (USCBP 2008a, p. 1– 14). In our evaluation of the potential 5; USCBP 2008b, p. 2–4; Rorabaugh flat-tailed horned lizards or ants. impacts of the plan’s implementation on Additionally, research has been 2010, p. 181). Prior to construction of the flat-tailed horned lizard (USFWS the border fence, the new fence and conducted in creosote-dominated ‘‘ 2008, p. 178), we concluded: After associated infrastructure was habitats in the Mojave Desert. reviewing the current status of this Researchers compared reptile metrics anticipated to result in reduction of the species, environmental baseline for the amount of illegal, cross-border traffic (measures) between sites used action area, effects of the proposed (USCBP 2008b, p. 3–18). Additionally, differentially by OHVs and control sites action, and cumulative effects, it is the as part of the installation of the border (Bury et al. 1977, pp. 1–23). Bury et al. Service’s biological opinion that the fence, a stabilized patrol road on the (1977, p. 11) found a significant action, as proposed, is not likely to U.S. side was constructed. The use of decrease in numbers of reptiles on OHV- jeopardize the continued existence of the road was also expected to result in used areas compared to numbers on the flat-tailed horned lizard. Loss of the an overall decrease in ground control sites in the Mojave Desert. Coachella Valley population would disturbance because Border Patrol However, the highest number of desert have a negligible [effect] on the status of agents would patrol from vehicles on horned lizards on any one plot occurred the species as a whole, since it makes the road rather than through OHV on a moderately used OHV site (Bury et up approximately 1 percent of the al. 1977, p. 10). In research conducted current range of the flat-tailed horned activity (USCBP 2008a, p. 2–7). Indeed, by both Busack and Bury (1974, p. 182) lizard. Persistence of the species in the evidence suggests the border fence has and Bury et al. (1977, p. 1), there Plan area is likely only with effective reduced illegal cross-border traffic and appeared to be an inverse relationship Plan implementation.’’ Additionally, associated OHV activity (Rorabaugh between increased use of OHVs and the approximately 94 percent of the 2010, p. 190), thereby reducing the abundance of lizards; this means that, as potential habitat where flat-tailed amount of potential impact to flat-tailed OHV use increased, lizard abundance horned lizards are known to occur in horned lizard habitat along the border decreased. Additionally, McGrann et al. the Thousand Palms conservation area from illegal trans-border OHV activity (2006, pp. 77–79) found that the density is land that is already protected (Table and subsequent law-enforcement OHV of flat-tailed horned lizards was lower 2), including about 62 percent that is activity by the Border Patrol. in areas of high OHV activity, as was the part of the Coachella Valley National Moreover, the scientific literature is average body mass of individual flat- Wildlife Refuge. mixed and inconclusive with respect to tailed horned lizards, suggesting the OHV activity along the United States- the impact of OHV activity on the flat- habitat quality—including harvester ant Mexico international boundary (border) tailed horned lizard and its habitat. abundance—in some high-use OHV was identified as a potential threat to Setser and Young (2000, p. 11) and areas was not as good; however, the the flat-tailed horned lizard and its Setser (2001, p. 12) found flat-tailed authors also noted that small sample habitat (FTHLICC 2003a, p. 12). The horned lizards avoided areas disturbed size may have allowed qualitative amount of impact to flat-tailed horned by OHVs. However, there was no differences between sites sampled to lizard habitat along the border is not difference in flat-tailed horned lizard affect their results. clear. To put the potential impact in habitat use between areas within 10 m

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(33 ft) of OHV trails and sites farther Air Facility (NAF) El Centro. MCAS or about 40 percent of flat-tailed horned away from OHV trails (Setser and Young Yuma manages approximately 46,458 ha lizard habitat in the United States, 2000, p. 11; Setser 2001, p. 12). Setser (114,800 ac) within the 53,014–ha within the Management Areas, of which and Young (2000, p. 11) and Setser (131,000–ac) Yuma Desert Management only 0.09 percent has been permitted for (2001, p. 12) concluded that: (1) OHV Area, while NAF El Centro manages impacts. Furthermore, in the United use might render sites less suitable to approximately 12,060 ha (29,800 ac) States, most of the species’ habitat is flat-tailed horned lizard use, because of within the 55,078–ha (136,100–ac) West federally or State (such as California the impacts of OHV activity on Mesa Management Area and 3,440 ha State Park) owned, where impacts to vegetation and soil characteristics; or (2) (8,500 ac) in the 46,660–ha (115,300–ac) habitat from development are OHV trails occur on sites not preferred East Mesa Management Area. The U.S. anticipated to be minimal. In Mexico, by flat-tailed horned lizards (e.g., barren Marine Corps and U.S. Navy are the amount of development that may ground with no plants or rocks). signatories to the Interagency occur in flat-tailed horned lizard habitat However, Gardner (2002) and Setser Conservation Agreement implementing is small relative to the large amount of (2004, p. 54) suggested that OHV the Rangewide Management Strategy. habitat that is available, and thus the activity did not have an effect on flat- The training ranges are primarily used effects to the species are expected to be tailed horned lizards at different areas for aircraft-related training. Activities low in magnitude. Therefore, current or in the Ocotillo Wells SVRA, on the basis that have the potential to impact flat- anticipated future urban, agricultural, or of observations. tailed horned lizard habitat include energy development throughout the In summary, while there has been non-exploding bombing practice, species’ range is not currently a some research on the adverse effects of ground-based training, target substantial threat to the flat-tailed OHV activity on vegetation, soils, and maintenance, clean up of target sites, horned lizard, nor do we expect it to flat-tailed horned lizards, its road maintenance, mobile target become a substantial threat in the applicability to flat-tailed horned lizard activity, and target and run-in-line foreseeable future. populations is limited and unreliable grading. Most military activities are Invasive, nonnative plants could because of the lack of scientific rigor confined to previously disturbed areas, increase the potential for wildland fire associated with the research designs. so the amount of destruction or in a desert environment where wildland Additionally, the effects of OHV activity modification of flat-tailed horned lizard fire is naturally infrequent. Research on flat-tailed horned lizard populations habitat is limited (FTHLICC 2003a, suggests that invasive, nonnative plant were not the primary research p.15). Additionally, the military is conversion of flat-tailed horned lizard questions. Nevertheless, these studies committed to be good stewards of lands habitat is limited to urbanized and have utility in generating hypotheses they control, and the two installations adjacent areas, and is not a substantive concerning variation in degree of OHV have incorporated measures to benefit threat to the species’ habitat throughout use and flat-tailed horned lizard the flat-tailed horned lizard and other its range. Also, frequent OHV activity abundance. At this time, we conclude wildlife resources into their planning, has the potential to affect flat-tailed that the available studies do not training, and management activities horned lizard habitat; however, the collectively show that OHV activity (Navy 2001, chapter 3; USAF and USMC available studies do not collectively causes declines in flat-tailed horned 2007, p. 1–8 and chapter 5). Therefore, show that OHV activity causes declines lizard populations throughout the range we do not anticipate military training in flat-tailed horned lizard populations of the species or that adverse OHV activities to substantially affect flat- throughout the range of the species or impacts pose a significant threat to flat- tailed horned lizard habitat now or in that adverse OHV impacts pose a tailed horned lizard habitat. the foreseeable future. significant threat to flat-tailed horned Management activities, including efforts lizard habitat. Lastly, military training Summary of Factor A Threats to reduce conflicts with actions that activities have limited impacts on the impact flat-tailed horned lizard habitats, Flat-tailed horned lizard habitat could ground and are not expected to would be enhanced by focused research. potentially be impacted by urban or substantially affect flat-tailed horned Impacts of OHV activity on flat-tailed agricultural development. However, due lizard habitat. We do not consider the horned lizard populations should be to the remote location and increasingly potential threats analyzed above to be studied using rigorous research designs limited availability of water, substantial threats to the flat-tailed to yield conclusions with high degrees urbanization and agricultural horned lizard, either individually or in of certainty (Ratti and Garton 1994, pp. conversion of flat-tailed horned lizard combination. Therefore, based on our 1–23) regarding the effects of OHV habitat will likely be limited in the review of the best available scientific activity on flat-tailed horned lizard United States and Mexico over the and commercial information, we find populations across the range of the foreseeable future. We note that the flat-tailed horned lizard is not species. In conclusion, OHV activity development of energy facilities is threatened by the present or threatened does not appear to be a significant threat increasing, especially in the destruction, modification, or to flat-tailed horned lizard habitat southwestern United States; however, curtailment of its habitat or range, either throughout its range at this time, nor is the overall acreage of impact from these now or in the foreseeable future. it likely to become a significant threat in projects, assuming all of the proposed B. Overutilization for Commercial, the foreseeable future. right-of-way applications are constructed, is small compared to the Recreational, Scientific, or Educational Military Training Activities range of the species. In the United Purposes The Rangewide Management Strategy States, we expect development impacts Within the context of this listing (FTHLICC 2003a, p.15) summarizes to occur outside of the existing factor, overutilization is the capture or military activity within the range of the Management Areas due to avoidance collection of individuals of a species to flat-tailed horned lizard. The species and minimization measures that result an extent (at a high enough rate) to occurs on two military installations: (1) from implementation of the Rangewide affect the status of the species. The western Barry M. Goldwater Range, Management Strategy. As of 2009, Historically, in the United States, flat- administered by Marine Corps Air signatory agencies control tailed horned lizards may have been Station (MCAS) Yuma, and (2) Naval approximately 185,653 ha (458,757 ac), among the species of horned lizard

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collected for the curio trade (Bolster and were depredated in a 2-year study areas. This suggests that the observed Nicol 1989, pp. 2 and 7). Flat-tailed (Muth and Fisher 1992, p. 33), although high level of predation of flat-tailed horned lizard were identified by Stewart the rate of predation they observed may horned lizards is an ‘‘edge effect’’ (1971, p. 33) as utilized in the pet trade. have been affected by the presence of associated with the interface between This species was also collected for the radio tags themselves by making the natural areas and areas of urban and scientific and educational purposes otherwise cryptically colored lizard agricultural development. Because the (Bolster and Nicol 1989, p. 9). However, more apparent to predators. For proportion of developed areas within the collection of the flat-tailed horned predation to be a significant threat to the the range of the species is small in lizard is now prohibited except by flat-tailed horned lizard, predation rates comparison to the undeveloped areas, permit in California (California must be high enough to affect the status we do not consider increased predation Administrative Code 40.10, Title 14) of the species such that mortality from associated with urbanization to be a and Arizona (Arizona Game and Fish predation outpaces births resulting in an significant threat to the species. We Regulation, Title 17, R12–4–443, overall population decline. Predation further consider predation as a Commission Order 43). The flat-tailed has been identified as a potential threat secondary effect of development, which horned lizard is also listed in the to the flat-tailed horned lizard is discussed under Factor E, below. Official Mexican Norm NOM–059– (FTHLICC 2003a, pp. 16–17). A Summary of Factor C Threats ECOL–2001, Mexico’s threatened summary from multiple sources in the species law, as a threatened species in scientific literature is presented in the Disease does not appear to be a threat Mexico (SEMARNAT 2002, p. 134), and Rangewide Management Strategy at this time, nor is it likely to become collection is prohibited without a (FTHLICC 2003a, p. 16), which a significant threat in the foreseeable permit. Because of the difficulty in identifies known or likely predators to future. Predation likely occurs in some locating these cryptically colored be six species of birds, five species of human-altered areas at higher than lizards, we expect unauthorized reptiles, two species of mammals, and typical rates; however, compared to the recreational collection to be rare. In one arthropod. Of these, the round- distribution of the species, relatively Mexico, Hammerson et al. (2007, p. 5) tailed ground squirrel (Spermophilus few flat-tailed horned lizards are likely noted that the species may be utilized tereticaudus) and the loggerhead shrike subjected to increased predation. in the pet trade. As noted in Rodriguez (Lanius ludovicianus) were highlighted Therefore based on our review of the (2002, p. 26), some people in Mexico as major predators (FTHLICC 2003a, p. best scientific and commercial information, we find the flat-tailed have flat-tailed horned lizards in their 16; see also Young and Young 2000, p. horned lizard is not threatened by yards, but it is unclear whether those 60; Young et al. 2004a, p. 65). Most of disease or predation, now or in the lizards are prevented from moving out. these predators occur naturally foreseeable future. We have no information on the (including historically) in areas magnitude of the pet trade, but horned occupied by flat-tailed horned lizards; D. The Inadequacy of Existing lizards in general are known to be thus, predation is not a threat that has Regulatory Mechanisms difficult to keep alive as captive pets emerged recently. (Stewart 1971, p. 34), including in In the 1993 proposed rule to list the Mexico (Rodriguez 2002, p. 26). This However, information from the species, we identified several State suggests that the pet trade is small. The scientific literature suggests that the (Arizona and California), U.S. Federal, information we have, although limited, populations of some of these predators and Mexican Federal laws and other does not suggest that the amount of are now higher as a result of manmade existing regulatory mechanisms that utilization that has occurred recently, changes to the landscape, resulting in could provide benefits to the flat-tailed regardless of purpose, has significantly increased predation of flat-tailed horned horned lizard (58 FR 62627), and we affected the status of the flat-tailed lizards in these areas (FTHLICC 2003a, concluded that these regulatory horned lizard. Therefore, based on our pp. 16–17; Young and Young 2005, p. mechanisms were inadequate to protect review of the best scientific and 8). For example, Barrows et al. (2006, the species or its habitat (58 FR 62628). commercial information, we find that pp. 492–493) found evidence suggesting In 1997, we also noted several State overutilization for any purpose is not a that loggerhead shrikes and other avian (Arizona and California), U.S. Federal, threat to the flat-tailed horned lizard, predators were responsible for reduced and Mexican Federal laws, but now or in the foreseeable future. populations of flat-tailed horned lizards particularly noted the benefits provided near wildland-urban interface, and to the flat-tailed horned lizard by the C. Disease or Predation Young and Young (2005, p. 8) suspected Interagency Conservation Agreement Disease occurs to some extent in round-tailed ground squirrel implementing the Rangewide nearly all wildlife populations, but it is populations are similarly augmented Management Strategy (62 FR 37858– only a threat if the disease is virulent to with manmade changes to landscape, 37859). In 2003, we again noted several the extent that it significantly impacts resulting in similar declines in flat- State (Arizona and California), U.S. the population. We are not aware of any tailed horned lizard populations in and Federal, and Mexican Federal laws and reports of disease in flat-tailed horned around urban areas. Additionally, the other existing regulatory mechanisms lizards. Thus, we do not consider cryptic coloration that allows flat-tailed that could provide benefits to the flat- disease to be a threat to the flat-tailed horned lizards to blend in with desert tailed horned lizard (68 FR 346). horned lizard anywhere within its soils may be of little use on paved roads, Because the Interagency Conservation range, nor is there any evidence to allowing increased levels of predation Agreement implementing the suggest it is likely to become a threat in (Young and Young 2000, p. 62). Rangewide Management Strategy is the foreseeable future. However, much of the range of the flat- voluntarily implemented on the part of Predation occurs naturally, and nearly tailed horned lizard is remote, away the signatories, we do not consider it to all populations of wildlife species are from areas of manmade change. Thus, be a regulatory mechanism per se. Some subject to some level of predation. for the flat-tailed horned lizard, entities have incorporated the Predation of flat-tailed horned lizards is predation does not appear to be Interagency Conservation Agreement known to occur. For example, 16 of 42 excessively high throughout its range into other regulatory mechanisms; in radio-tagged flat-tailed horned lizards but instead localized near developed such cases, the Interagency

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Conservation Agreement is mentioned afforded by the application of section we anticipate impacts to the species and in the context of those regulatory 7(a)(4) of the Act because the potential its habitat may be avoided or mechanisms. Additionally, two habitat threats facing the flat-tailed horned minimized. conservation plans (HCPs) within the lizard are not substantial (see the other Approved Habitat Conservation Plans— range of the flat-tailed horned lizard listing factors). Section 10(a)(1)(B) of the Act cover the species and provide mitigation Incidental Protection Via Other Listed Under section 10(a)(1)(B) of the Act, for and conservation of habitat. While Species implementation of these HCPs will the Service may issue ‘‘incidental take’’ provide localized benefits to the flat- The withdrawal of the proposed rule (i.e., taking of endangered species that is tailed horned lizards populations within to list the flat-tailed horned lizard will incidental to, but not the purpose of, the HCP boundaries, these HCPs cover not affect the listing status of other carrying out of an otherwise lawful a very small portion of the flat-tailed listed species, and the flat-tailed horned activity, see 50 CFR 402.02) permits for horned lizard’s range and will not lizard may receive some level of listed animal species to non-Federal substantially influence the overall status protection in the United States through applicants, which provide exemptions of the species. The Interagency implementation of the Act because of to the take prohibitions under section 9 Conservation Agreement and the two overlapping ranges or proximity to other of the Act. To qualify for an incidental HCPs are discussed in greater detail in federally listed species. These take permit, applicants must develop, the Background section above. associated federally listed species fund, and implement a Service- In the preceding analyses of the include Coachella Valley fringe-toed approved habitat conservation plan that, threats to the flat-tailed horned lizard lizard (Uma inornata), Astragalus among other requirements, does not under Factors A, B, and C, and in our lentiginosus var. coachellae (Coachella jeopardize the continued existence of analysis of threats under Factor E, Valley milk-vetch), Astragalus covered species, and details measures to below, all of the threats presented are of magdalenae var. peirsonii (Peirson’s minimize and mitigate the impact of the low magnitude, are non-imminent, and/ milk-vetch), bighorn sheep in the approved incidental taking on covered or cover very small portions of the Peninsular Ranges (Ovis canadensis species. As discussed in the Background species’ range. In the sections that nelsoni), and desert tortoise (Gopherus section and under Factor A, there are follow, we first discuss the existing agassizii). two existing incidental take permits that regulatory mechanism(s) that would be The federally threatened Coachella include the flat-tailed horned lizard as removed as a result of the withdrawal of Valley fringe-toed lizard is restricted to a covered species: the Coachella Valley the Coachella Valley, but its distribution the proposed rule to list the species. MSHCP and the Lower Colorado MSCP. overlaps with the northern portion of Then we review the existing regulatory Regardless of the withdrawal of the the flat-tailed horned lizard’s range in mechanisms that would remain in effect proposed rule to list the species, the the Coachella Valley. However, the flat- to address the potential threats existing HCPs, and the conservation tailed horned lizard may use additional discussed herein under the other listing they provide, would remain in effect. habitat within the Coachella Valley in factors. which the fringe-toed lizard does not Additional U.S. Federal Mechanisms U.S. Federal Laws occur. The Coachella Valley MSHCP Federal Land Policy and Management addresses the Coachella Valley fringe- Section 7(a)(4) of the Act Act toed lizard, Coachella Valley milk- The Act contains provisions for vetch, and the flat-tailed horned lizard. The Federal Land Policy and Federal agencies to confer with the Federal actions not covered by the Management Act of 1976 (43 U.S.C. Secretary on any action that is likely to Coachella Valley MSHCP that may affect 1701 et seq.) (FLPMA), which provides jeopardize the continued existence of the Coachella Valley fringe-toed lizard, overall direction to the BLM for any species proposed to be listed under the Coachella Valley milk-vetch, or both conservation and management of public the Act. Commonly called a are subject to consultation with the lands, allows the agency to participate ‘‘conference,’’ this requirement would no Service under section 7 of the Act. in Interagency Conservation longer apply to the flat-tailed horned These consultations may include Agreements. Section 601 required the lizard once the withdrawal of the avoidance or minimization measures preparation of the California Desert proposed listing rule is finalized. A that benefit the listed species and, Conservation Area (CDCA) Plan. The conference opinion is an advisory where they co-occur, the flat-tailed CDCA Plan was amended to formally mechanism by which the Service horned lizard. Similarly, consultations incorporate the Rangewide Management recommends measures to avoid adverse on the federally endangered bighorn Strategy into BLM’s land use planning, effects or jeopardy to the species. There sheep of the Peninsular Ranges may including formal adoption of the BLM- are no requirements to implement include measures that benefit flat-tailed controlled Management Areas reasonable and prudent measures and horned lizards in the Western and comprising the East Mesa Flat-tailed terms and conditions or for adoption of Coachella Valley Populations where Horned Lizard Management Area, West reasonable and prudent alternatives to suitable habitat for both species is in Mesa Flat-tailed Horned Lizard avoid impacts to species or habitat. In close proximity at the toe of slope of the Management Area, and Yuha Desert this regard, the conference opinion mountains; however, the amount of Flat-tailed Horned Lizard Management requirement under the Act provides such overlap is likely to be minimal. Area (BLM 2004, p. 2). Additionally, little if any additional regulatory Likewise, the flat-tailed horned lizard section 103(a) of the FLPMA defines an protection for this species; although it may marginally benefit from Area of Critical Environmental Concern may provide some benefits to the flat- consultations addressing the federally (ACEC), which allows creation of areas tailed horned lizard by informing threatened Astragalus magdalenae var. ‘‘where special management attention is Federal agencies of potential adverse peirsonii and the federally threatened required * * * [for] fish and wildlife effects to the species that may result desert tortoise where they co-occur, but resources.’’ BLM lands comprise much from their activities. However, the these areas of overlap are also likely of the U.S. range of the flat-tailed survival of the flat-tailed horned lizard minimal. When the flat-tailed horned horned lizard, including the is not dependent on any protections lizard overlaps with other listed species, aforementioned Management Areas.

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Additionally, the BLM has designated measures that may be incorporated into California State Laws ACECs for wildlife resources within the Federal projects. We conclude FWCA is California Endangered Species Act range of the flat-tailed horned lizard. an adequate regulatory mechanism The BLM’s implementation of FLPMA, within the confines of its applicability, The flat-tailed horned lizard is not through land management plans that but its applicability is limited. The listed under the California Endangered incorporate certain provisions of the minor benefits provided by FWCA will Species Act (CESA), the State’s primary Rangewide Management Strategy continue regardless of the withdrawal of regulatory mechanism to protect including the avoidance, minimization, the proposed rule to list the flat-tailed species. Therefore, CESA provides no mitigation (compensation), and horned lizard. benefit to the flat-tailed horned lizard. management measures, helps to reduce Sikes Act California Environmental Quality Act the severity of existing potential threats to the flat-tailed horned lizard, In 1997, section 101 of the Sikes Act The California Environmental Quality especially development and OHV (16 U.S.C. 670a) was revised by the Act (CEQA) (chapter 2, section 21050 et activity. We conclude FLPMA is an Sikes Act Improvement Act to authorize seq. of the California Public Resources adequate regulatory mechanism within the Secretary of Defense to implement a Code) requires State and local the confines of its applicability—that is, program to provide for the conservation government agencies to consider and allowing BLM to better manage flat- and rehabilitation of natural resources disclose environmental impacts of tailed horned lizard habitat and on military installations. To do so, the projects and to avoid or mitigate them implement the Rangewide Management Department of Defense was required to where possible. Under CEQA, public Strategy on BLM lands. Because much work with Federal and State fish and agencies must prepare environmental of the U.S. portion of the range of the wildlife agencies to prepare an documents to disclose environmental flat-tailed horned lizard is comprised of Integrated Natural Resources impacts of a project and to identify BLM land, FLPMA is an important Management Plan (INRMP) for each conservation measures and project regulatory mechanism that helps to facility with significant natural alternatives. Section 15380 of the CEQA reduce the already low-level threats to resources. The INRMPs provide a Guidelines indicates that species the species in these areas. planning tool for future improvements; designated as ‘‘species of special Implementation of the CDCA Plan, as provide for sustainable multipurpose concern’’ (see below) should be included amended, and the incorporated use of the resources, including activities in an analysis of project impacts if they provisions of the Rangewide such as hunting, fishing, trapping, and can be shown to meet the criteria of Management Strategy will continue non-consumptive uses; and allow some sensitivity outlined therein (Comrack et regardless of the withdrawal of the public access to military installations to al. 2008, p. 2). However, CEQA itself proposed listing rule for the species. facilitate their use. Implementation of does not guarantee that conservation the measures included in these plans is measures will be implemented; the lead National Environmental Policy Act subject to funding availability. The agency may either require mitigation The National Environmental Policy primary purpose for military lands, through changes to a project, or Act (NEPA) (42 U.S.C. 4321 et seq.) including most areas of flat-tailed determine that overriding requires all Federal agencies to formally horned lizard habitat, is to provide for considerations make mitigation document, consider, and publicly military support and training. infeasible (CEQA Sec. 21002). In the disclose the environmental impacts of Two major military installations are latter case, projects may be approved major Federal actions and management within the U.S. range of the flat-tailed that cause significant environmental decisions that have significant effects on horned lizard, the MCAS Yuma (within damage, such as impacts to species or the human environment (including the Barry M. Goldwater Range) and the their habitat. Therefore, whether CEQA natural resources), but NEPA does not NAF El Centro, both are signatories to is an adequate regulatory mechanism require that mitigation alternatives be the Interagency Conservation Agreement within the confines of its applicability implemented. Additionally, NEPA and are implementing the Rangewide depends on the law’s application and applies only to actions by Federal Management Strategy. Both installations the determination of the lead agency agencies, so private landowners are not have incorporated aspects of the involved. The minor benefits provided required to comply with NEPA unless a Rangewide Management Strategy into by CEQA will continue regardless of the Federal agency is involved through their respective INRMPs, including withdrawal of the proposed rule to list provision of Federal funding or a avoidance and minimization measures, the species. Federal permit. Although NEPA plus monitoring and management Natural Community Conservation requires disclosure of the effects of activities (Navy 2001, pp. 3–14 to 3–16; Planning Act proposed Federal actions, it does not USAF and USMC 2007, pp. 6–2 and 6– afford direct protection to the flat-tailed 8; see also USAF et al. 2006 entire). The NCCP program is a cooperative horned lizard. Additionally, areas designated as Flat- effort involving the State of California tailed Horned Lizard Management Areas and numerous private and public Fish and Wildlife Coordination Act under the Rangewide Management partners to protect regional habitats and Through the Fish and Wildlife Strategy include military-owned areas species. The primary objective of NCCPs Coordination Act (16 U.S.C. 661 et seq.) (FTHLICC 2003a, pp. 51–53). Regardless is to conserve natural communities at (FWCA), we may recommend of the withdrawal of the proposed rule the ecosystem scale while discretionary conservation measures to to list the species, the application of the accommodating compatible land use, avoid, minimize, and offset impacts to Sikes Act would continue and the including urban development (http:// fish and wildlife resources resulting benefits to the flat-tailed horned lizard www.dfg.ca.gov/habcon/). Natural from Federal projects and water would continue within the confines of Community Conservation Plans help development projects authorized by the its applicability—that is, providing identify and provide for the regional or U.S. Army Corps of Engineers. benefits to the flat-tailed horned lizard area-wide protection of plants, animals, Therefore, FWCA may provide some and its habitat on military facilities and and their habitats, while allowing protection for the species and its habitat implementing the Rangewide compatible and appropriate economic through avoidance and minimization Management Strategy on military lands. activity. Many NCCPs are developed in

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conjunction with habitat conservation within the confines of its applicability— only change in regulatory protections plans prepared under the Act, including that is, an administrative designation would be the removal of the conference the Coachella Valley MSHCP. that increases the level of awareness and requirement under section 7(a)(4) of the Regardless of the withdrawal of the analysis (such as under CEQA) for flat- Act. Since a conference opinion is only proposed rule to list the flat-tailed tailed horned lizard in California. The advisory in nature, we do not expect horned lizard, the existing NCCPs, and benefits provided by the Species of this change to have any significant effect the protections they provide, would Special Concern designation will on the status of the species. The remain in effect. continue regardless of the withdrawal of remainder of the existing regulatory the proposed rule to list the flat-tailed mechanisms summarized above will California Administrative Code horned lizard. remain in place and will continue to California Administrative Code 40.10, provide benefits to the species. The Arizona State Laws Title 14, prohibits the collection of flat- aforementioned existing regulatory tailed horned lizards without a permit. Arizona Game and Fish Regulation mechanisms provide some level of Therefore, we conclude the California Arizona Game and Fish Regulation, protection for the species and its Administrative Code is an adequate Title 17, R12–4–443, Commission Order habitat. This includes several laws or regulatory mechanism within the 43 prohibits the collection of flat-tailed mechanisms that reduce potential confines of its applicability—that is, horned lizards without a permit by threats, such as State laws that restrict limiting or preventing overutilization of indicating that there is no ‘‘open season’’ the collection of flat-tailed horned the flat-tailed horned lizard in to collect the species (AGFD 2009, p. 8). lizards, or planning documents California. The benefits provided by Additionally, the Arizona Game and developed under FLPMA or the Sikes California Administrative Code 40.10, Fish Department has included the flat- Act that incorporate measures from the Title 14, will continue regardless of the tailed horned lizard on the draft List of Rangewide Management Strategy. withdrawal of the proposed rule to list Wildlife of Special Concern in Arizona, Therefore, we conclude the existing the flat-tailed horned lizard. which the State uses to prioritize regulatory mechanisms are not Species of Special Concern species for planning and funding inadequate and do not threaten the species throughout all or a significant The State’s Species of Special purposes, although State regulations do not exist in Arizona to protect this portion of its range, now or in the Concern (SSC) designation is an foreseeable future. administrative designation that carries species’ habitat at this time. We no formal legal status. According to conclude Arizona Game and Fish E. Other Natural or Manmade Factors Comrack et al. (2008, pp. 1–4), its intent Regulation is an adequate regulatory Affecting Its Continued Existence is to focus attention on animals deemed mechanism within the confines of its For Factor E, we assess the natural or to be at conservation risk, stimulate applicability—that is, limiting or manmade threats to the species that research, and achieve conservation and preventing overutilization of the flat- were not addressed under the previous recovery of these animals before they tailed horned lizard in Arizona. The four factors. In the 1993 proposed rule meet California Endangered Species Act benefits provided by the Arizona Game to list the species as threatened and in criteria for listing as a State endangered and Fish Regulation, Title 17, R12–4– the 2003 withdrawal document, we or threatened species. The flat-tailed 443, Commission Order 43 will considered the potential effects of horned lizard is on the list of reptile and continue regardless of the withdrawal of pesticide spraying and prolonged amphibian species of special concern in the proposed rule to list the flat-tailed drought under this factor. Also in these California (Jennings and Hays 1994, pp. horned lizard. two Federal Register publications, we 134–141). Mexican Federal Law addressed the effects of OHV use on the As stated in Comrack et al. (2008, p. species and its habitat under Factor A. 2), sections 15063 and 15065 of the Official Mexican Norm Similarly, in those earlier assessments, CEQA Guidelines, which address how The Official Mexican Norm NOM– we addressed the potential effects an impact is identified as significant, are 059–ECOL–2001, Mexico’s threatened associated with fragmentation on the particularly relevant to SSCs. Project- species law, lists the flat-tailed horned species and its habitat under Factor A. level impacts to listed (endangered, lizard as a threatened species Also, in our 2006 withdrawal document threatened, or rare species) species are (SEMARNAT 2002, p. 134). The (71 FR 36750–36751), the scope of generally considered significant, thus Mexican law may be implemented to which was limited by court order, we requiring lead agencies to prepare an modify development projects or support addressed historical habitat loss as a Environmental Impact Report to fully creation of Natural Protected Areas, but component of Factor A on the grounds analyze and evaluate the impacts. successful implementation occurs by that Factor A addresses the curtailment Moreover, section 15380 of the CEQA individuals or groups outside of the of a species’ habitat or range as a threat Guidelines indicates that SSCs should Mexican government. We conclude to its continued existence, but this be included in an analysis of project Official Mexican Norm may be an rationale was flawed because Factor A, impacts if they can be shown to meet adequate regulatory mechanism within as discussed here and under Factor A in the criteria of sensitivity outlined the confines of its applicability—that is, the present document, is limited to therein (Comrack et al. 2008, p. 2). In reducing threats to the species in current and anticipated losses of habitat, assigning ‘‘impact significance’’ to Mexico. The benefits provided by the not past losses. Because of the populations of non-listed species, Official Mexican Norm NOM–059– confusion presented in previous analysts usually consider factors such as ECOL–2001 will continue regardless of analyses, we have emphasized in the population-level effects, proportion of the withdrawal of the proposed rule to current analysis the differences between the taxon’s range affected by a project, list the flat-tailed horned lizard in the present and future habitat loss from past regional effects, and impacts to habitat United States. habitat loss, including how features. ‘‘fragmentation’’ as a concept interacts Therefore, we conclude the State’s Summary of Factor D with the topic of habitat loss. Species of Special Concern designation With the withdrawal of the proposal To address explicitly the previously is an adequate regulatory mechanism to list the flat-tailed horned lizard, the identified threat of ‘‘fragmentation,’’ we

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need to address the specific threats populations, below, we primarily refer on by inbreeding, genetic drift and other encompassed by that ambiguous term. to populations as being physically factors.’’ For a population to become However, these threats include ones that separated, or potentially so. extirpated (locally extinct), these are best addressed under separate listing Barriers prevent or severely limit extrinsic and intrinsic forces and factors factors under the Act. As mentioned contact (genetic interchange) between must significantly affect the population. previously, the term fragmentation populations. Thus, an artificial barrier These forces and factors are more likely includes habitat loss. Factor A addresses can split a population into two (or more) to be significant to small populations present (current) or threatened populations (Jackson 2000, p. 4). For (Goodman 1987, pp. 11–34; Pimm et al. (anticipated) destruction, modification, animals that can move freely (vagile 1988, pp. 757–785; Lande 1993, pp. or curtailment of a species’ habitat or animals), like the flat-tailed horned 911–927; Frankham 1996, pp. 1500– range. Factor A does not address threats lizard, barriers prevent individuals from 1508; Henle et al. 2004, pp. 207–251). posed by past losses of habitat. How the moving from one area into another. Our 1993 and 2003 assessments of the species is affected by past habitat loss— Barriers not only include physical flat-tailed horned lizard have described or in other words, the present-day hindrances that prevent movement (e.g., flat-tailed horned lizard populations as ramifications of those past actions of a wall or a river), but may also include ‘‘fragmented.’’ As discussed previously, habitat destruction—is better addressed areas that a species may be disinclined fragmentation is an imprecise term, but under Factor E. The effects of past to enter (e.g., unsuitable habitat) or areas one that clearly is associated with the habitat loss include in particular the of increased mortality (e.g., busy roads, breaking up of populations into smaller effects of manmade barriers on or areas with an elevated number of populations through the introduction of populations and edge effects. Barriers predators) across which individuals artificial barriers. As discussed in the may divide otherwise intact populations would be unlikely to successfully Background section, historical into smaller populations, and those traverse. agricultural development (and its smaller populations may be more The division of populations into associated urban development) has susceptible to other effects (see below). other, smaller populations may or may largely occurred in contiguous blocks. Thus, below, we assess the effects of not be deleterious; it largely depends on These large swaths of human-created barriers and small populations and edge the size of the resulting populations, non-habitat have, for the most part, effects. We also assess the previously with small populations more likely to exacerbated natural barriers separating identified potential effects to the species experience problems than large the Western, Eastern, and Southeastern from pesticide spraying, OHV use, and populations, as discussed below. Populations, and severed the somewhat prolonged drought; we also address the Moreover, small populations may be tenuous connection between the potential effects associated with global disproportionately affected by other Coachella Valley Population and the climate change not previously natural and manmade factors compared Western Population. As a consequence identified. to large populations, such as edge of the past development, the effects, also discussed below. Thus, the geographical area occupied by these Barriers and Small Populations creation of artificial barriers results in four populations became smaller. With As mentioned previously, as used habitat loss (see Factor A) and may also the decrease in the amount of habitat herein a ‘‘population’’ refers to a loosely affect the species through potential area, we expect populations of flat- bounded, regionally distributed effects associated with the subsequent tailed horned lizards in those areas to collection of individuals of the same isolation, which largely depends upon also be smaller (a decrease in the species. Thus, individuals of a given the size of the resulting populations. abundance of individuals) (such as species when considered together Because the threats from barriers and Hokit and Branch 2003, p. 261). within some boundary may be small populations are connected, we The point at which a population considered a population. For example, discuss the potential threats faced by becomes a ‘‘small population’’ is not the group of individuals bounded small populations generally and then clear and varies by species-specific or within the entire range of the species discuss the potential effects of barriers situational-specific factors. There is may be considered a population, and small population sizes on the flat- disagreement among scientists and sometimes referred to as the ‘‘entire tailed horned lizard. considerable uncertainty as to the population’’ or ‘‘population as a whole.’’ The decline of a population is population size adequate for long-term Similarly, groups of individuals within determined by a number of forces and persistence of wildlife populations; the entire population may be considered factors that are often grouped into however, there is agreement that to occur separately from each other, intrinsic and extrinsic. As described by population viability over the long term forming multiple populations. In typical Soule´ and Simberloff (1986, pp. 27–28), is more likely to be ensured if usage, a separation is often a literal ‘‘extrinsic forces include deleterious population sizes are in the thousands of separation—that is a physical division, interactions with other species individuals rather than hundreds (Traill by a barrier for instance—but it may also (increases in predation, competition, et al., 2010, p. 32, see also Reed et al. be a figurative separation; for example, parasitism, disease or decreases in 2003, p. 30, Table 3 therein). In an arbitrary grouping of individuals for mutualistic interactions) and deleterious vertebrates, a population of 5,000 is the purposes of discussion. Regardless events or changes to habitat or the often used as a minimum number of the criteria used to separate and physical environment. Intrinsic factors needed for high likelihood of viability group individuals, a species may be include random variation in genetically over the long term (Traill et al., 2010, p. considered to comprise one or more based traits of the species and 32), while Reed et al. (2003, p. 30) populations, depending on how the interactions of these traits with the estimated that roughly 7,000 breeding- term is used. Moreover, because the environment. These include: age adults is the minimum number term is loosely defined, a given (1) Demographic stochasticity, which is necessary for a vertebrate population to population could be considered to random variation in sex ratio [and] in likely remain viable over the long term. consist of other smaller populations, birth and death rates, * * * (2) social However, as stated by Thomas (1990, p. sometimes hierarchically referred to as dysfunction or behaviors that become 324), ‘‘there is no ‘magic’ population ‘‘subpopulations.’’ For the purposes of maladaptive at small population sizes; size that guarantees the persistence of our discussion of barriers and small [and] (3) genetic deterioration brought animal populations.’’ He went on to note

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that populations of some vertebrates individuals per ha (0.1 individuals per Depending on how roads are have survived for decades with ac) (see Background section) there are constructed, they may serve as physical population sizes of hundreds or even likely more than 50,000 adult flat-tailed hindrances to the movement of flat- dozens of individuals, adding horned lizards in the Western tailed horned lizards. For example, ‘‘populations that occupy habitat Population, 85,000 in the Eastern raised roadbeds, steep curbs, and fragments that are far too small to hold Population, and 322,000 in the roadway dividers may contribute to thousands of individuals may still Southeastern Population. We making a roadway a physically possess great conservation potential’’ acknowledge that there are numerous impassible barrier for flat-tailed horned (Thomas 1990, p. 326). Moreover, the assumptions in these calculations that lizards. Similarly, railways may serve as amount of time that most authors limit accuracy of the extrapolated physical barriers. However, bridges and consider to be ‘‘long term’’ is many population sizes; however, even using culverts, especially those with larger- decades or even centuries (for example, the most conservative density value, sized openings, may allow flat-tailed see Shaffer 1981, p. 132; Soule and these three populations are of sufficient horned lizards to cross under the Simberloff 1986, p. 28; Traill et al. 2010, size such that any threats associated physical impediments along roads and p. 31; see also Reed et al. 2003, p. 30, with small populations would be railways (Painter and Ingraldi 2007, p. Table 3 therein). Although minimum unlikely. However, there are potential 17). Although it is not known whether population sizes for shorter time periods barriers that may subdivide the the openings under such structures are would be correspondingly smaller (see otherwise apparently continuous used regularly by the species in the Figure 1 in Traill et al. 2010, p. 31), we Western, Eastern, and Southeastern wild, it is likely that the undercrossings use the long-term population size to be Populations. We examine subdivisions with natural substrates created by larger conservative. within these three populations, below. culverts, and especially bridges, are As discussed in the Background used to some extent. Additionally, Subpopulations Within the Western, section, and discussed further in the blowing sand, which is not atypical for Eastern, and Southeastern Populations present section, the distribution of the much of the range of the flat-tailed flat-tailed horned lizard is divided into For the flat-tailed horned lizard, as a horned lizard, may build up along discrete populations. Thus, to assess the diminutive terrestrial animal, a number roadways and railways. Thus, it is threat implied by the term of manmade changes to the landscape possible that accumulated sand, at least ‘‘fragmentation,’’ it is more appropriate may serve as barriers (see FTHLICC until the sand is cleared by maintenance to consider the individual populations 2003a, p. 14). These include: crews, may provide a ‘‘bridge’’ over the than to assess the population-as-a- (1) Railways, canals, and certain types physical structures that prevent flat- whole. Below we assess the four of roadways that are physical tailed horned lizard movement. For geographical Populations. We first hindrances to the movement of flat- example, the railway through the sandy examine the Western, Eastern, and tailed horned lizards; (2) developed Gran Desierto de Altar may be less of a Southeastern Populations, each as a areas (unsuitable habitat) into which barrier than railways in less sandy whole. Then, looking at those three flat-tailed horned lizards may be portions of the species’ range due to Populations further, we note that disinclined to enter; and (3) busy blowing and drifting sands that may potential barriers within the larger roadways, powerline corridors, and provide passage over tracks. Populations may divide each Population areas adjacent to developed areas (that into smaller subpopulations. Lastly, we Additionally, roads that do not serve have artificial perches and nearby examine the Coachella Valley as physical hindrances may be barriers artificial food sources resulting in Population. We treat the Coachella for other reasons. Flat-tailed horned higher densities of predators) that are Valley Population separately from the lizards, particularly males (Young and areas of increased mortality for flat- other three Populations because the Young 2000, p. 19), are often sighted on tailed horned lizards (FTHLICC 2003a, current distribution of flat-tailed horned paved roads (Mayhew 1965, p. 104; lizards in the Coachella Valley occurs in p. 14; see also Boarman et al. 1997, pp. Turner and Medica 1982, p. 822; two widely isolated areas and are more 54–58; Fagan et al. 1999, pp. 165–182; Johnson and Spicer 1985, p. 40; like the subpopulations created by Jackson 2000, pp. 1–14; Germaine and Stebbins 2003, p. 304). This, combined barriers within the Western, Eastern, Wakeling 2001, pp. 229–237; Young and with their propensity to not flee from and Southeastern Populations. Thus, we Young 2005, pp. 1–11; Barrows et al. oncoming traffic (Young and Young take advantage of the concepts 2006, pp. 486–494; Shepard et al. 2008, 2000, p. 60), may make flat-tailed developed in our discussion of barrier- pp. 288–296). horned lizards particularly susceptible created subpopulations to assess the We expect these potential barriers to traffic-related road mortality (Nicola Coachella Valley Population. will be variable in how thoroughly they and Lovich 2000, p. 211; Gardner et al. prevent movement of flat-tailed horned 2001, p. 10). The stretches of multi-lane Western, Eastern, and Southeastern lizards, and thus variable in the extent highways (Interstate 8 and State Route Populations to which they prevent contact between 86) that cross areas within the current There are no direct, reliable estimates individuals and separate populations. range of the flat-tailed horned lizard of flat-tailed horned lizard population Canals generally extend for long have, on average, over 25,000 vehicles size for the four geographically distances without overcrossings, and pass over them daily, while the smaller, separated populations. The size of the flat-tailed horned lizards may be two-lane highways of State Routes 78 Western Population, Eastern Population, reluctant to use (go over) what few and 98 within the species’ range have and Southeastern Population areas are crossings exist (bridges); as such, canals roughly 3,500 to 5,500 vehicles per day, 341,989 ha (845,073 ac), 169,617 ha are likely impermeable barriers in the on average (Caltrans 2008, electronic (419,133 ac), and 1,073,551 ha same way the Colorado River has data). The increased level of vehicle (2,652,802 ac) respectively (Coachella separated populations. However, as traffic on the multi-lane highways along Valley Population area is discussed discussed below, roadways and with the greater number of physical separately, below). Even at the lowest railways, and the infrastructure hindrances that may result from (most conservative) estimated density of associated with border security may or multiple lanes is more likely to serve as adult flat-tailed horned lizard of 0.3 may not constitute complete barriers. a barrier than the smaller, two-lane

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highways. For example, the population horned lizards are no longer at ground however, in the analysis that follows we of flat-tailed horned lizards occupying level (FTHLICC 2010, p. 10), the shifting discuss the situations in which such the small part of the Southeastern sand has also resulted in gaps under the barriers may be semipermeable. Population north of Interstate 8 (1,018 fence that flat-tailed horned lizards may Additionally, for the purposes of the ha (2,516 ac)) (see below) is small use to cross under the fence (Rorabaugh analysis, where two or more potential enough and isolated enough to exhibit 2010, p. 190). Thus, we do not barriers are adjacent to each other (e.g., some evidence of inbreeding or genetic anticipate the fence proper to be a portions of Interstate 8 and the All- drift (Culver and Dee 2008, p. 2), complete physical hindrance to flat- American Canal), we mapped them as a suggesting Interstate 8 in this area is an tailed horned lizard movement. The single barrier. All of the area values effective barrier preventing movement additional infrastructure and activity (hectares and acres) are approximate of flat-tailed horned lizards (see below). may deter flat-tailed horned lizard and are not as precise as the values However, Interstate 8 likely poses less of movement or allow for increased given; however, we believe they are a physical hindrance where it crosses mortality. However, in total, we do not sufficiently accurate for this coarse-scale the Eastern Population where blowing believe the level of activity to be high analysis (especially because we used sand fills in gaps along the road edge, enough to be a complete barrier to flat- conservative estimates of flat-tailed although the traffic volume remains tailed horned lizard movement (see also horned lizard densities). high. Another way roadways may be Rorabaugh 2010, p. 190). For example, We used the conservative estimated barriers is that the cryptic coloration genetic data from both sides of the density of 0.3 adult flat-tailed horned that allows flat-tailed horned lizards to border in the Southeastern Population lizards per ha (0.1 per ac) to determine blend in with desert soils may be of suggests that populations of flat-tailed whether potentially isolated parts little use on paved roads, allowing horned lizards in Arizona are not between barriers were likely to contain increased levels of predation (Young genetically isolated from neighboring more than 7,000 adults, in other words, and Young 2000, p. 62) (see Factor C, populations in Mexico (Culver and Dee to be large enough to avoid threats that Disease and Predation). Thus, even 2008, p. 10). As such, the border fence may be associated with small though flat-tailed horned lizards may be is likely a semipermeable barrier, not a population size (see above). Where able to physically cross two-lane roads complete barrier, for the species. populations were ‘‘small,’’ we also (Barrows 2006, p. 119), these roads may To assess the threat of barriers to the present other potential population sizes be barriers to flat-tailed horned lizards flat-tailed horned lizard, we examined using higher densities, including the for other reasons. maps of the region, including GIS data still-conservative, but perhaps more However, it is not clear whether and aerial and satellite imagery. The realistic (for certain ‘‘parts’’), value of 0.7 roadways or other potential barriers are areas in which flat-tailed horned lizards individuals per ha (0.3 per ac) (see complete barriers. They may instead be are currently distributed contain Population Dynamics section, above). ‘‘semipermeable’’ barriers, reducing numerous potential manmade barriers. As described in the Population contact between populations, but not As mentioned above, the Coachella Dynamics section in the Background, stopping it. This may be especially true Valley Population area has numerous these density estimates were derived for small roads, especially gravel and barriers, and the flat-tailed horned from data that were collected at sites in unsurfaced roads and OHV ‘‘routes.’’ lizard is only known from two relatively the northern portion of the species’ Although the amount of contact needed small areas. Thus, as summarized range. As a result, we are confident that to maintain population connectivity of below, we focused our attention on the the density estimates used are flat-tailed horned lizards is not known, three relatively contiguous Western, conservative. We do not have density Mills and Allendorf (1996, p. 1517) Eastern, and Southeastern Populations. estimates for the southern portion of the suggested that if 1 to 10 individuals per For this analysis, we used GIS data of species’ range; thus, we do not know if generation successfully cross a the species’ ‘‘current distribution’’ as 0.3 or 0.7 individuals per ha (0.1 or 0.3 semipermeable barrier, that level of delineated by the 2003 Rangewide per ac) are as conservative. movement is likely sufficient to Management Strategy to examine the Nevertheless, because these values are maintain the connection between size of the areas between those features at the low end of a fairly wide range (0.3 populations, provided the overall we considered likely barriers. Barriers to 4.4 adults per ha (0.1 to 1.8 per acre)), population is of sufficient size. Thus, a divide the areas of habitat into we believe them to be within the potential barrier would have to severely subareas—termed herein as ‘‘parts.’’ density range even in the southern areas limit flat-tailed horned lizard movement Similarly, barriers divide populations of of the species’ distribution. throughout its length and at all times for flat-tailed horned lizards into smaller Additionally, as discussed near the it to be a complete barrier; as such, only populations, or subpopulations. beginning of the ‘‘Barriers and Small a few potential barriers are likely Features we considered potential likely Populations’’ section, above, the point at complete barriers. barriers included: (1) The All-American which a population becomes ‘‘small’’ The ‘‘tactical infrastructure,’’ Canal and the Coachella Canal, which varies from species to species and from including fencing, lighting, and access are likely to be complete barriers situation to situation. Stated another and patrol roads (collectively, the throughout their lengths; and way, the forces and factors that are more ‘‘border fence’’), along portions of the (2) Interstate 8; State Routes 78, 86, and likely to be significant threats to a international border has the potential to 98; Mexico Federal Highways 2 and 8; ‘‘small’’ population of a given species are serve as a barrier. The actual fencing in the (old) coastal highway (which is not guaranteed to be significant threats these areas includes vehicle and being upgraded to a multi-lane highway, to a given population of a given size. We pedestrian fences that are constructed to but we do not have GIS data for the new have limited information on the effects allow movement of small animals route); the international border; and such forces and factors may have on the (USCBP 2008a, pp. 1–4 to 1–6 and several railways, which are likely to be flat-tailed horned lizard. For example, Appendix B; USCBP 2008b, pp. 2–5 and semipermeable barriers to varying even though information in the 8–9). Although the shifting sand has degrees along their lengths. scientific literature suggests the meant some of the small slots that were For the purposes of dividing the areas previously mentioned population north incorporated into fine-mesh pedestrian into ‘‘parts,’’ we assumed all potential Interstate 8 is exhibiting some evidence fence to allow movement of flat-tailed barriers were complete barriers; of inbreeding or genetic drift (Culver

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and Dee 2008, p. 2), we do not have identified as small, isolated parts are (89,105 ha (220,183 ac)) (Part W–3; specific information as to whether or to likely to experience adverse effects Table 3), which includes the West Mesa what degree that population’s status is associated with small population size. Management Area; (3) the area in the being affected; the information in the Western Population vicinity of the southeastern corner of scientific literature (as discussed above) Anza-Borrego Desert State Park (42,443 suggests that this population is likely The potential barriers listed above ha (104,879 ac)) (Part W–5; Table 3); and split the Western Population area into facing a greater risk from threats (4) the long, narrow area south of 12 parts (Table 3, Figures 3 and 4), four associated with genetic deterioration, Mexico Federal Highway 2 in Baja of which are likely to support but we have no data (one way or the populations greater than 7,000 California (74,254 ha (183,486 ac)) (Part other) to assess that particular individuals, even with the most W–12; Table 3). Although the long, population’s status. Thus, for the conservative of the estimated densities. narrow nature of the area in Baja purposes of evaluating the potential These include: (1) The area north of California may make threats more threats associated with the implied State Route 78 (77,566 ha (191,670 ac)) pronounced (Faaborg et al. 1995, p. meaning of ‘‘fragmentation’’ to the flat- (Part W–1; Table 3), which includes the 366), it remains a large habitat area. tailed horned lizard, we have assumed Borrego Badlands Management Area Thus, it is likely flat-tailed horned that the populations of flat-tailed and Ocotillo Wells SVRA; (2) the area lizards in these four areas are not ‘‘small horned lizards in areas that we immediately south of State Route 78 populations.’’

TABLE 3—THE SIZE (AREA) OF THE ‘‘PARTS’’ CREATED BY BARRIERS (SEE TEXT) WITHIN THE WESTERN POPULATION AND OUR DETERMINATION AS TO WHETHER THE SPECIFIED PART IS UNLIKELY TO BEATRISK OF DELETERIOUS EFFECTS OF SMALL POPULATIONS AT THE CONSERVATIVE DENSITIES OF 0.3 OR 0.7 INDIVIDUALS PER HA (0.1 OR 0.3 PER AC)

Is this part large enough to avoid deleterious effects associated with small populations when the density is assumed to be: Part identifier (country) Area of part 1 0.3 individuals per ha 0.7 individuals per ha (0.1 per ac) (0.3 per ac)

W–1 (U.S.) ...... 77,566 ha (191,670 ac) ...... yes ...... yes. W–2 (U.S.) ...... 8,777 ha (21,688 ac) ...... no ...... no. W–3 (U.S.) ...... 89,105 ha (220,183 ac) ...... yes ...... yes. W–4 (U.S.) ...... 539 ha (1,331 ac) ...... no ...... no. W–5 (U.S.) ...... 42,443 ha (104,879 ac) ...... yes ...... yes. W–6 (U.S.) ...... 4,081 ha (10,083 ac) ...... no ...... no. W–7 (U.S.) ...... 19,527 ha (48,252 ac) ...... no ...... yes. W–8 (U.S.) ...... 110 ha (272 ac) ...... no ...... no. W–9 (U.S.) ...... 10,873 ha (26,867 ac) ...... no ...... yes. W–10 (Mex.) ...... 294 ha (726 ac) ...... no ...... no. W–11 (Mex.) ...... 14,420 ha (35,632 ac) ...... no ...... yes. W–12 (Mex.) ...... 74,254 ha (183,486 ac) ...... yes ...... yes 1 Area values are estimated through a GIS-based assessment. Despite the level of precision presented, area values are approximate; how- ever, we believe they are accurate enough to draw the conclusions presented.

BILLING CODE 4310–55–P

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BILLING CODE 4310–55–C because it is likely to support higher Wash at the far west end of Part W–6 Of the remaining eight populations, densities of flat-tailed horned lizards (BLM and CEC 2010, p. C.2–22; USFWS three (Parts W–4, W–8, and W–10; Table and where one of the demographic plots 2010c, p. 57). A 2,630-ha (6,500-ac) 3) were remnants of a few hundred from which the data for density solar generation facility has been hectares each, totaling less than 1,000 estimates were gathered (see Population proposed in this area, which is likely to ha (2,500 ac). If the flat-tailed horned Dynamics section, above), and the one transform much of it into unsuitable lizards in these areas are isolated from in Mexico is immediately adjacent to habitat. However, requirements for the other flat-tailed horned lizard the Yuha Desert Management Area, we construction and operation of the solar populations, we expect they will be believe it is reasonable to conclude that generation facility include avoidance of ‘‘small populations’’ and that they, the density of 0.7 individuals per ha (0.3 impacts to the major washes that cross therefore, are more likely to be per ac) is a realistic but still the site, which would allow the negatively impacted by the deleterious conservative density estimate to use. possibility of connectivity (USFWS effects associated with small Moreover, as mentioned above, the 2010c, p. 57). populations sizes. Although the border fence is likely a semipermeable The last area, between State Route 86 populations in these parts may have barrier, allowing some connectivity and the Salton Sea, is over 8,000 ha some connection to their respective between the Yuha Desert Management (19,800 ac) (Part W–2; Table 3, Figure adjacent parts, Parts W–4, W–8, and W– Area and the areas of habitat south of 3). The multi-lane State Route 86 is 10 are very small and on the periphery, the international border. Thus, it is likely a substantial barrier, but our and any such connection would likely likely flat-tailed horned lizards in these interpretation of aerial imagery suggests be tenuous at best. areas are not ‘‘small populations.’’ there are several bridges that may allow Of the five remaining parts, three One of the last two remaining parts is some connection. That connection, (located between Interstate 8 on the the area between Interstate 8 and the combined with the size of the area, may north and Mexico Federal Highway 2 to railway to the north (Part W–6; Table 3); reduce the risk this population will south) (Parts W–7, W–9, and W–11; it is over 4,000 ha (9,900 ac). This part suffer from threats associated with Table 3) were large enough to likely should have some connectivity with the ‘‘small populations.’’ support more than 7,000 flat-tailed areas to the north because it is unlikely In sum, for the Western Population, horned lizards if the density of flat- the railway is a complete barrier, and it assuming the identified potential tailed horned lizards was 0.7 may even have limited connection to barriers are complete barriers (which is individuals per ha (0.3 per ac). Given the south across Interstate 8 because of not likely, as explained above, although that the two U.S. areas contain the Yuha culverts and bridges, especially the large we do not know how permeable they Desert Management Area, an area that bridge that allows Interstate 8 to span may be), and assuming the most was selected to be a Management Area the typically dry South Fork Coyote conservative density of 0.3 flat-tailed

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horned lizards per ha (0.1 per ac), we small population size. Thus, the nine parts within three subareas (Table calculate that nearly 83 percent of the Western Population is not substantially 4). Two major canals, which we expect area is in parts of sufficient size such composed of ‘‘small populations.’’ are complete barriers, divide the overall that the populations of flat-tailed Therefore, we conclude the flat-tailed area. The east-to-west-flowing All- horned lizards therein are not likely to horned lizards in the Western American Canal isolates the southern be substantially affected by the factors Population are not substantially roughly 20 percent (southern subarea) associated with small population size. If threatened by effects associated with from the northern 80 percent, which in we assume a slightly less conservative barriers that subdivide populations or turn is divided by the southeast-to- density (though still at the low end of the deleterious effects that may follow, northwest-flowing Coachella Canal, the reported range) of 0.7 individuals nor do we expect barriers to be a threat essentially splitting the northern area in per ha (0.3 per ac), we calculate about in the foreseeable future. half (East Mesa subarea on the west and 96 percent of the area within the Eastern Population the Algodones Dunes subarea to the Western Population is in large enough The potential barriers listed above east). We discuss parts within these blocks to not be substantially affected by split the Eastern Population area into three subareas separately below.

TABLE 4—THE SIZE (AREA) OF THE ‘‘PARTS’’ CREATED BY BARRIERS (SEE TEXT) WITHIN THE EASTERN POPULATION AND OUR DETERMINATION AS WHETHER THE SPECIFIED PART IS UNLIKELY TO BEATRISK FROM DELETERIOUS EFFECTS OF SMALL POPULATIONS AT THE CONSERVATIVE DENSITIES OF 0.3 OR 0.7 INDIVIDUALS PER HA (0.1 OR 0.3 PER AC)

Is this part large enough to avoid deleterious effects associated with small populations when the density is assumed to be: Part identifier (country) Area of part 1 0.3 individuals per ha 0.7 individuals per ha (0.1 per ac) (0.3 per ac)

E–1 (U.S.) ...... 16,863 ha (41,669 ac) ...... no ...... yes. E–2 (U.S.) ...... 156 ha (385 ac) ...... no ...... no. E–3 (U.S.) ...... 12,135 ha (29,986 ac) ...... no ...... yes. E–4 (U.S.) ...... 50,270 ha (124,220 ac) ...... yes ...... yes. E–5 (U.S.) ...... 50,721 ha (125,334 ac) ...... yes ...... yes. E–6 (U.S.) ...... 8,968 ha (22,160 ac) ...... no ...... no. E–7 (U.S.) ...... 2,867 ha (7,085 ac) ...... no ...... no. E–8 (U.S.) ...... 4,140 ha (10,230 ac) ...... no ...... no. E–9 (Mex.) ...... 23,496 ha (58,060 ac) ...... yes ...... yes. 1 Area values are estimated through a GIS-based assessment. Despite the level of precision presented, area values are approximate; how- ever, we believe they are accurate enough to draw the conclusions presented.

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The southern subarea of the Eastern small population and may be at greater lizards at the most conservative density. Population—that is, south of the All- risk from the deleterious effects However, because of this area’s American Canal—is divided by the associated with small populations. The proximity to the East Mesa Management international border, with the part next smallest part is a triangle of flat- Area, it likely supports higher densities between the canal and border totaling tailed horned lizard habitat between of flat-tailed horned lizards such that at 8,968 ha (22,160 ac) (Part E–6; Table 4), Interstate 8 and the All-American Canal 0.7 flat-tailed horned lizards per ha (0.3 and the part on the Mexico side of the (Part E–8; Table 4). It is 4,140 ha (10,230 per ac), this part would support a international border totaling 23,496 ha ac), likely too small of an area to population that would not be at risk (58,060 ac) (Part E–9; Table 4). However, support a ‘‘large population,’’ and the from threats associated with small as mentioned previously, the border busy, multi-lane Interstate 8 probably population size. Moreover, State Route fence is probably a semipermeable has low ‘‘permeability’’ for flat-tailed 78 in this area, because blowing sand barrier. As such, we expect the area of horned lizard movement. The third part has filled in any gaps along the road’s flat-tailed horned lizard habitat to the in the East Mesa subarea (Part E–5; edge such that it is not a physical south of the All-American Canal (Parts Table 4), the area north of Interstate 8, hindrance and it has a lower traffic E–6 and E–9 combined) could be south of State Route 78 and west of the volume (Caltrans 2008, electronic data), considered together. However, we Coachella Canal, is 50,721 ha (125,334 is likely a semipermeable barrier, estimate that roughly 6,400 ha (15,800 ac) and includes the East Mesa allowing contact of flat-tailed horned ac) in the easternmost portions of these Management Area, which is considered lizards between the two areas (north and two parts contain areas of deep, actively to be higher-quality flat-tailed horned south of the highway). As such, we shifting sands of the Algodones Dunes lizard habitat. This part is large enough expect the area of flat-tailed horned that are likely rarely used by flat-tailed to support a large population; moreover, lizard habitat north of Interstate 8 and horned lizards. Despite this, the area is it is likely that the density in this area west of the Coachella Canal (Parts E–3 large enough so as to likely not be is at the higher end of the range of and E–5 combined) is large enough so affected by the deleterious effects density estimates—thus, the population as to not be affected now or in the associated with ‘‘small populations.’’ is likely much larger and not at risk of foreseeable future by the deleterious The East Mesa subarea (the western deleterious effects associated with small effects associated with small half of the northern 80 percent) is populations. The fourth part in the East populations. divided into four parts. The smallest Mesa subarea (Part E–3; Table 4), the The Algodones Dunes subarea (the part (Part E–2; Table 4) is a very small, area to the north of State Route 78 and eastern half of the northern 80 percent) isolated remnant of potential habitat west of the Coachella Canal, is 12,135 is divided into three parts. The part (156 ha (385 ac)) at the far northern end ha (29,986 ac) and unlikely to support north of Interstate 8, south of State of the Eastern Population area; it is a a ‘‘large population’’ of flat-tailed horned Route 78 and east of the Coachella

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Canal, is 50,270 ha (124,220 ac) (Part E– barriers are complete barriers (which is adults per ha (0.1 per ac) density 4; Table 4), large enough to support a not likely, see above, although we do estimate. Similarly, Part E–3 likely large population at the most not know how permeable they may be), supports a population of flat-tailed conservative density estimate. However, and assuming the most conservative horned lizards at a density greater than this area is mainly composed of the density of 0.3 adult flat-tailed horned the most conservative 0.3 adults per ha Algodones Dunes, which is an area of lizards per ha (0.1 per ac) for all the (0.1 per ac). Thus, if we (1) exclude deep, actively shifting sand that is likely parts, we calculate that about 73 percent parts E–1, E–4, and the deep-sand areas rarely used by flat-tailed horned lizards of the area is in large enough blocks that at the east end of parts E–6 and E–9 (Turner et al. 1980, p. 14). Flat-tailed the populations of flat-tailed horned because these areas are naturally poor- horned lizards in this area are likely lizards therein are not likely to be quality habitat and are likely rarely used (naturally) restricted to the peripheral affected by threats associated with small by flat-tailed horned lizards; and (2) portions of the dunes. Moreover, large populations. However, the Eastern consider part E–3, E–5, and the non- portions of this region include areas of Population is divided by the All- deep-sand portions of E–6 and E–9 intense recreational OHV activity, American Canal and the Coachella (combined; see above) as likely including portions of the peripheral Canal, which we expect are complete supporting large populations of flat- areas of the dunes, which may reduce barriers to flat-tailed horned lizards. As tailed horned lizards, then about 93 the habitat quality in those areas (see such, the Eastern Population area is percent of the Eastern Population area Factor A). The third part of this subarea divided into three subareas. The size of likely supports populations of flat-tailed (Part E–1; Table 4), the area north of the population in the portion east of the horned lizards that are large enough to State Route 78, is 16,863 ha (41,669 ac), Coachella Canal, the Algodones Dunes be unlikely affected by threats at the most conservative density subarea, is not clear because much of associated with small populations. estimates supporting a population that the area includes the deep-sand areas of Therefore, we conclude that, overall, the may be at risk from the deleterious the Algodones Dunes, which is likely flat-tailed horned lizards in the Eastern effects of small population size. This low-quality habitat for the flat-tailed Population are not substantially part is also mainly composed of the horned lizard. As such, even using our threatened now or in the foreseeable deep, actively shifting sands of the conservative density estimate, this area future by effects associated with barriers Algodones Dunes, suggesting that higher likely supports—naturally, even prior to that subdivide populations or the densities of flat-tailed horned lizards are any manmade effects—fewer flat-tailed deleterious effects that may follow. unlikely. However, unlike the areas to horned lizards compared to the other Southeastern Population the south of State Route 78, most of the subareas in the Eastern Population than area is designated as Wilderness and, as would be expected from its size. For the Identified potential barriers divide the such, OHV activity is prohibited. subarea south of the All-American Southeastern Population area into 13 Moreover, as in the East Mesa subarea, Canal, the border fence between part E– parts (Table 5). By far, the largest single State Route 78 is likely a semipermeable 6 and E–9 is likely permeable to some part (Part SE–5; Table 5, Figures 6 and barrier, allowing contact of flat-tailed extent, but roughly 6,400 ha (15,800 ac) 7) is in Mexico between the horned lizards between the two areas in the easternmost portions of these two international border and the Mexicali to (north and south of the highway). Thus, parts contain areas of deep, actively Puerto Pen˜ asco railway, northwest of the areas on the periphery of the shifting sands of the Algodones Dunes Mexico Federal Highway 8. It is over Algodones Dunes are likely used by flat- that are likely rarely used by flat-tailed 720,000 ha (1,779,000 ac) and includes tailed horned lizards within parts E–1 horned lizards. Thus we expect the the bulk of the Gran Desierto de Altar and E–4, but the majority of these two populations of flat-tailed horned lizards where the species occurs in the sandy parts, the areas of deep, shifting sands in parts E–6 and E–9 are connected, and flats and low, more-stabilized dunes of the Algodones Dunes, likely even subtracting the area of deep sand within this region (Rorabaugh 2008, p. contributes little to the Eastern in the east of these two parts, the 39; Rorabaugh and Young 2009, p. 183), Population, and likely contributed little subarea south of the All-American Canal but the deep, actively shifting sands of even before the manmade barriers and is large enough to likely support a much of this area are likely rarely used OHV activity. The smallest part (Part E– population of flat-tailed horned lizards by flat-tailed horned lizards (Rodriguez 7; Table 4), between the All-American that is unlikely to be substantially 2002, p. 18; Rorabaugh and Young 2009, Canal and Interstate 8, in the southeast affected by the threats associated with p. 182). Nevertheless, the sheer size and corner of the Eastern Population area, is small population size. For the subarea limited manmade alterations to the area about 2,867 ha (7,085 ac). Using the west of the Coachella Canal and north suggests that this area likely supports a conservative density estimate, the of the All-American Canal, the population large enough to avoid the population of flat-tailed horned lizards populations of flat-tailed horned lizards deleterious effects associated with small in this part may be at risk of deleterious in parts E–3 and E–5 are likely populations, even if they are limited to effects associated with small connected because State Route 78 likely the peripheral portions of the ‘‘sand populations. This part, though sandy, is is a semipermeable barrier. Moreover, sea.’’ This large part touches nearly all not dominated by the deep, actively Part E–5 contains the East Mesa of the other parts in the Southeastern shifting sands of the main dunes. Management Area where the density of Population, and in our discussion of the In sum, for the Eastern Population, flat-tailed horned lizards is likely other parts, we refer to this large, central assuming the identified potential greater than the most conservative 0.3 part as the Gran Desierto part.

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TABLE 5—THE SIZE (AREA) OF THE ‘‘PARTS’’ CREATED BY BARRIERS (SEE TEXT) WITHIN THE SOUTHEASTERN POPU- LATION AND OUR DETERMINATION AS WHETHER THE SPECIFIED PART IS UNLIKELY TO BEATRISK OF DELETERIOUS EFFECTS OF SMALL POPULATIONS AT THE CONSERVATIVE DENSITIES OF 0.3 OR 0.7 INDIVIDUALS PER HA (0.1 OR 0.3 PER AC)

Is this part large enough to avoid deleterious effects associated with small populations when the density is assumed to be: Part identifier (country) Area of part 1 0.3 Individuals per ha 0.7 Individuals per ha (0.1 per ac) (0.3 per ac)

SE–1 (U.S.) ...... 56,736 ha (140,198 ac) ...... yes ...... yes. SE–2 (U.S.) ...... 1,018 ha (2,516 ac) ...... no ...... no. SE–3 (U.S.) ...... 8,804 ha (21,755 ac) ...... no ...... no. SE–4 (U.S.) ...... 1,364 ha (3,371 ac) ...... no ...... no. SE–5 (Mex.) ...... 720,168 ha (1,779,573 ac) ...... yes ...... yes. SE–6 (Mex.) ...... 8,354 ha (20,643 ac) ...... no ...... no. SE–7 (Mex.) ...... 496 ha (1,226 ac) ...... no ...... no. SE–8 (Mex.) ...... 110,242 ha (272,414 ac) ...... yes ...... yes. SE–9 (Mex.) ...... 110,857 ha (273,934 ac) ...... yes ...... yes. SE–10 (Mex.) ...... 5,175 ha (12,788 ac) ...... no ...... no. SE–11 (Mex.) ...... 10,585 ha (26,156 ac) ...... no ...... yes. SE–12 (Mex.) ...... 833 ha (2,058 ac) ...... no ...... no. SE–13 (Mex.) ...... 38,919 ha (96,171 ac) ...... yes ...... yes. 1 Area values are estimated through a GIS-based assessment. Despite the level of precision presented, area values are approximate; how- ever, we believe they are accurate enough to draw the conclusions presented.

BILLING CODE 4310–55–P

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BILLING CODE 4310–55–C these four parts are completely isolated, development of Puerto Pen˜ asco, and The railway that runs from Mexicali the population of flat-tailed horned densities may be lower. The to Puerto Pen˜ asco and south, along with lizards along the coast of the Gulf of southernmost (coastal) part (Part SE–13; the ‘old’ coastal highway (see above), California northwest of Puerto Pen˜ asco Table 5) is also separated by the create four parts, three small and one is likely not at risk from the deleterious railway-highway combination, but it is large, along the coast of the Gulf of effects associated with small large (38,919 ha (96,171 ac)) and is California northwest of Puerto Pen˜ asco. populations. likely to support a population large The three small parts along the coast are Mexico Federal Highway 8, the enough to avoid deleterious effects from 8,354 ha (20,643 ac) (Part SE–6; Table northeast to southwest-running highway small populations size even at the most 5), 496 ha (1,226 ac) (Part SE–7; Table from Sonoita (on the international conservative density. These three 5), and 5,175 ha (12,788 ac) (Part SE–10; border, outside of the range of the flat- coastal parts are separated from the Table 5). These parts may be at risk from tailed horned lizard) to Puerto Pen˜ asco, large interior part (Part SE–9; Table 5), the deleterious effects associated with separates the Gran Desierto part from which is 110,857 ha (273,934 ac) and small populations; however, the road the southeastern-most portion of the large enough to support considerably and railroad separating them from the Southeastern Population. The more than 7,000 flat-tailed horned Gran Desierto part are likely not southward continuation of the railway lizards. Additionally, if the railway- complete barriers. We expect that and the parallel-running coastal highway combination separating the blowing sand periodically covers the highway further divides this portion three coastal parts (Parts SE–11, SE–12, railway line and any gaps along the into a total of four parts. One of these and SE–13) from the larger interior part sides of the road, allowing some level of parts is very small (833 ha (2,058 ac)) is not a complete barrier, which is connectivity between flat-tailed horned (Part SE–12; Table 5) and confined to a possible because of blowing sand, then lizard populations on the coast with narrow strip along the coast. It may be the two larger coastal parts could those in the Gran Desierto part. at greater risk of deleterious effects receive dispersing flat-tailed horned Similarly, the one large coastal part associated with small populations. lizards from the large interior part, northwest of Puerto Pen˜ asco (110,242 ha Another narrow coastal part is larger which may help further reduce the (272,414 ac)) (Part SE–8; Table 5) is also (10,585 ha (26,156 ac)) (Part SE–11; likelihood of deleterious effects likely connected with the Gran Desierto Table 5) and could support enough flat- associated with ‘‘small populations.’’ part; however, Part SE–8 is likely large tailed horned lizards to avoid Moreover, Mexico Federal Highway 8 enough by itself to support a population deleterious effects of small populations may also be permeable, suggesting that large enough that it would not be at risk if the densities were 0.7 individuals per the southernmost portion of the from deleterious effects of small ha (0.3 per ac). However, this area Southeastern Population (Parts SE–9, populations. Because we do not believe includes a portion of the urban SE–11, SE–12, and SE–13 combined)

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may also be connected with the future by effects associated with barriers Thousand Palms and Dos Palmas extremely large Gran Desierto part (Part that subdivide populations or the reserves are anticipated to be 1,707 ha SE–5). deleterious effects that may follow. (4,219 ac) and 2,078 ha (5,134 ac), Lastly, the portion of the Southeastern For the Western, Eastern, and respectively (Table 2). Of these, 94 Population in the United States is Southeastern Population areas percent of the Thousand Palms reserve divided into four parts, including one combined, about 91 percent of the is already in protected status, while 34 large part (see below) and three smaller 1,585,157 ha (3,917,008.25 ac) area is in percent of the Dos Palmas reserve is parts, the latter including one north of large enough blocks that the populations protected (Table 2). Using the Interstate 8 and two west of the new of flat-tailed horned lizards therein are conservative estimated density of 0.3 Yuma Area Service Highway. The part not likely to be affected by threats adult flat-tailed horned lizards per ha north of Interstate 8 is 1,018 ha (2,516 associated with small populations. As (0.1 per ac), neither of these reserves— ac) (Part SE–2; Table 5) and may be at mentioned above, the part that is presently or even at their anticipated risk of deleterious effects associated primarily composed of the Gran size—is large enough to support a ‘‘large with small populations. We expect the Desierto de Altar is very large; it makes population.’’ Thus, these two small, multi-lane Interstate 8 to be nearly a up about 45 percent of the total area of fully isolated occurrences may be more complete barrier along this stretch of the the three populations combined and is likely to experience deleterious effects road and, as mentioned above, the larger than the Western and Eastern associated with small population sizes. evidence suggests that the population Population areas combined. Without the In our evaluation of the monitoring and there may be exhibiting inbreeding or Gran Desierto part, about 84 percent of management of flat-tailed horned lizard genetic drift (Culver and Dee 2008, p. 2). the total area is in parts that are likely populations and habitat expected under The two small parts west of the Yuma to contain populations large enough to the Coachella Valley MSCHP (USFWS Area Service Highway are 8,804 ha avoid deleterious effects associated with 2008, Appendix A, p. 322), we stated: (21,755 ac) (Part SE–3; Table 5) and small populations. Thus, despite not ‘‘The proposed Plan provides reasonably 1,364 ha (3,371 ac) (Part SE–4; Table 5); having complete population data for the competent direction for monitoring and both may have small populations that species throughout its range, through adaptive management, but not all details could be at risk from the deleterious this analysis of size of the habitat areas, can be anticipated beforehand and effects of small population size. The and application of conservative much would depend on how the large part in Arizona (56,736 ha estimates (the smallest density value monitoring and adaptive management is (140,198 ac)) (Part SE–1; Table 5) is within the estimated range, and the implemented. We assume the mostly composed of the Yuma Desert largest population size value below implementation of the monitoring and Management Area and is large enough which we are considering (for our adaptive management plan would to avoid deleterious effects from small analysis of this species) a ‘‘small strictly adhere to the guidance in the population size. Culver and Dee (2008, population’’), we conclude that the flat- Plan. The extra pressures of edge effects pp. 1–14) also sampled the Yuma Desert tailed horned lizard populations are not and invasive species may be buffered by Management Area and did not report small and the species is not habitat- management to prevent pressures that any evidence of inbreeding or genetic limited in the United States or Mexico. would push a naturally low population drift in flat-tailed horned lizards from In conclusion, this evaluation to extinction. Populations are expected this large part, in contrast to the small, suggests that despite the presence of to increase in numbers again if isolated part (Part SE–2) north of multiple barriers that potentially divide anthropogenic factors are effectively Interstate 8. the Western, Eastern, and Southeastern managed.’’ Additionally, as noted above, In sum, for the Southeastern Population areas into smaller parts, even small populations in small habitat Population, assuming the identified most of the areas within the current areas may be viable in the long term; potential barriers are complete barriers distribution outside of the greater however, for the purposes of this (which is not likely, see above, although Coachella Valley are in parts large analysis (to be conservative) we are we do not know how permeable they enough to support populations of flat- assuming they are not. Therefore, we may be), and assuming the most tailed horned lizards that are large conclude the continued existence of the conservative density of 0.3 flat-tailed enough to avoid deleterious effects Coachella Valley Population is likely to horned lizards per ha (0.1 per ac), we associated with small populations. face significant threats within the calculate that about 97 percent of the Therefore, the implied meaning of foreseeable future. area is in large enough blocks that the fragmentation is not a significant threat populations of flat-tailed horned lizards to the flat-tailed horned lizard Summary for Barriers and Small therein are not likely to be affected by throughout its range or within the Populations threats associated with small Western, Eastern, and Southeastern Past assessments identified populations. However, much of the Population areas. ‘‘fragmentation’’ as a threat to the flat- dune areas of the Gran Desierto de Altar tailed horned lizard. Fragmentation, as are likely to have few, if any, flat-tailed Coachella Valley Population a term used in conservation biology, is horned lizards. Nevertheless, given the The Coachella Valley Population ambiguous. To address the implied limited amount of manmade differs from the other three in that it has meaning of the term, we assessed development within large areas of the been highly affected by past agricultural potential barriers and the resulting flat- Southeastern Population and the fact development and recent (and tailed horned lizard population sizes that about 97 percent of the area continuing) urban development (see throughout the species’ range. contains large blocks of flat-tailed Factor A). As mentioned previously, the Barriers prevent movement of horned lizard habitat, the Southeastern only areas with recent detections of flat- individuals and, thus, restrict or prevent Population is not substantially tailed horned lizards are within the gene flow. As such, barriers subdivide composed of ‘‘small populations.’’ Thousand Palms and the Dos Palmas larger populations into smaller ones. For Therefore, we conclude the flat-tailed reserves. The precise amount of habitat vertebrate species, populations of more horned lizards in the Southeastern that is occupied is not known, but based than about 7,000 individuals are not Population are not substantially on an analysis of habitats within the likely to be affected by deleterious threatened now or in the foreseeable Coachella Valley MSHCP plan, the intrinsic and extrinsic forces and factors

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over the long term. Not all potential deterioration because of isolation and tailed horned lizard habitat (Barrows et barriers are complete barriers and some small population size, we do not have al. 2006, p. 492); thus, we expect the potential barriers may be direct information on the status of that effect of Argentine ants to be limited to ‘‘semipermeable.’’ Movement of 1 to 10 population. Thus, based on information areas adjacent to edges that have water individuals per generation across a from the scientific literature on the sources. semipermeable barrier is likely enough potential effects of small population Although edge effects may result in to maintain connectivity between size, for the purposes of this threats increased mortality of flat-tailed horned populations. assessment, we have assumed these lizards, primarily resulting from The populations of flat-tailed horned ‘‘small’’ populations of flat-tailed horned increased levels of predation, the area lizards in the Western, Eastern, and lizards are being substantially affected affected is within several hundred Southeastern Population areas are by threats associated with small meters (yards) of the edge. As discussed potentially divided by artificial population size or are likely to be in the ‘‘Barriers and Small Populations’’ manmade barriers. Flat-tailed horned substantially affected by threats section, much of the area occupied by lizards are difficult to detect, and associated with small population size in the flat-tailed horned lizard is in large population estimates are limited to a the foreseeable future. areas (or ‘‘parts’’). In such areas or parts, few, well-surveyed areas. Density Even so, our evaluation suggests that the ratio of linear edge compared to the estimates of adult flat-tailed horned despite the presence of multiple barriers areal size of the part is small, meaning lizards range from as low as 0.3 that potentially divide the Western, large parts have larger ‘‘interior’’ areas individuals per ha (0.1 per ac) to as Eastern, and Southeastern Population that are not affected by edge effects. As much as 4.4 individuals per ha (1.8 per areas into smaller parts, most of the area such, the populations of flat-tailed ac), depending on the analysis used (see within the current distribution outside horned lizards in large areas or parts are Background section). Our evaluation of of the greater Coachella Valley are in less likely to be substantially affected by the range of the species suggests that the parts large enough to support edge effects. Conversely, smaller parts Western, Eastern, and Southeastern populations of flat-tailed horned lizards have a smaller percentage of their area Population areas were divided by larger than 7,000 individuals, meaning that is likely to be affected by edge manmade barriers into 12, 9, and 13 they are not habitat-limited and are not effects. As such, flat-tailed horned lizard ‘‘parts,’’ respectively. Using the lowest likely to suffer from threats associated populations in the small parts are more (most conservative) estimates of 0.3 with small populations now or in the likely to be substantially affected by adult flat-tailed horned lizards per ha foreseeable future. As such, the implied edge effects. (0.1 per ac), we calculated that the meaning of term ‘‘fragmentation’’ is not Because ‘‘parts’’ are created by Western, Eastern, and Southeastern a threat to the flat-tailed horned lizard infrastructural elements associated with Population areas had about 83 percent, throughout its range. urban and agricultural development, the 73 percent, and 97 percent of the areas small ‘‘parts’’ are more likely near urban Edge Effects (respectively) in parts likely to support and agricultural areas. Moreover, populations that are large enough to Another effect associated with because edge effects are most avoid deleterious effects associated with fragmentation and barriers is that there pronounced near urban and agricultural small populations. For those values, we are more habitat edges. When two development, the flat-tailed horned assumed all identified potential barriers ecosystems are separated by an abrupt lizards in small parts are the most likely were complete barriers; however, the transition (an ‘‘edge’’), there may be an to be substantially affected by edge circumstance for each individual part interaction between two adjacent effects. Thus, edge effects are an added varies, and some of the potential ecosystems, known as an edge effect threat faced by flat-tailed horned lizard barriers we identified are likely to not (Murcia 1995, p. 58). As noted populations in the small parts. As such, be complete barriers. As such, some of previously, predation of flat-tailed edge effects are not additional threats to the parts we identified as separate may horned lizards may be greater adjacent the flat-tailed horned lizard, but instead contain populations of flat-tailed horned to urban and agricultural areas (Barrows are part of the threats faced by flat-tailed lizards that are actually connected with et al. 2006, p. 486), and may extend horned lizard populations in small neighboring populations. Thus, we several hundred meters (yards) from the parts. Therefore, like small population believe these percentages are neighboring developed area (Young and size, we do not believe edge effects are conservative because we used the Young 2005, p. 7). Additionally, a significant threat to the flat-tailed conservative density estimates and the invasive, nonnative plants may also horned lizard now or in the foreseeable parts, as analyzed, may not actually occur at higher densities along road future. contain separate populations of flat- edges (Gelbard and Belnap 2003, p. Pesticide Spraying tailed horned lizards. 420); however, native plant growth may Additionally, the Coachella Valley also increase along roads (Lightfoot and Past assessments identified the Population area has numerous barriers Whitford 1991, p. 310). Increased plant spraying of pesticides as part of the and the remaining flat-tailed horned growth may lead to increased seeds, California Department of Food and lizards are restricted to two small areas. which may benefit harvester ants, the Agriculture’s Curly Top Virus Control The populations of flat-tailed horned primary food of the flat-tailed horned Program as a threat to the flat-tailed lizards in these areas are likely to be lizard. horned lizard, mainly in the East Mesa, affected by threats associated with small Additionally, the invasive, nonnative West Mesa, and Yuha Desert (58 FR population size. Argentine ant (Linepithema humile) has 62627; FTHLICC 2007, p. 20). As We again note that we have very little been found to be a problem for coastal described in the program’s specific data regarding whether or to horned lizards (Phrynosoma coronatum) environmental assessment (BLM 2007b, what degree populations of flat-tailed in habitat edges (Suarez et al. 1998, p. p. 8), beet curly top virus is a disease horned lizards are actually being 2041; Suarez and Case 2002, p. 291). of commercially important crops, and affected by threats associated with small However, Argentine ants do not tolerate also backyard vegetable and flower population size. Even for the flat-tailed hot, arid conditions (Holway et al. 2002, gardens. The only known vector of beet horned lizard population in Part SE–2, p. 1610) and are not known to be a curly top virus is an insect known as the which may be exhibiting genetic problem away from habitat edges in flat- sugar beet leafhopper (Circulifer

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tenellus). The Curly Top Virus Control (2) Application of malathion within (Muth and Fisher 1992, p. 33). Vehicle Program includes aerial and ground- the geographic range of the [flat-tailed drivers may not see or recognize flat- based spraying of malathion, which is horned lizard] will consist of no more tailed horned lizards because their the only product registered in California than a single treatment per given area cryptic coloration makes them difficult for the control of sugar beet leafhopper per year. to spot or they may be interpreted as on rangeland (BLM 2007b, p. 15). The (3) All application [within flat-tailed rocks. Moreover, the species’ propensity areas to be sprayed (treated) are horned lizard habitat] will be aerial. No to freeze rather than flee makes them prioritized; treatment priorities are spraying from off-road vehicles or use of particularly susceptible. Impacts from given to areas subject to perennial virus off-road vehicles on other than vehicles are more likely when the infection, areas sustaining significant designated roads will be used within lizards are on or near the surface; infection from the previous year, and [flat-tailed horned lizard] habitat. hibernating flat-tailed horned lizards are areas with the highest current sugar beet Beyond the avoidance and generally buried deep enough that they leafhopper populations (BLM 2007b, p. minimization measures incorporated are not crushed by vehicles driving over 8). into the Curly Top Virus Control them (Grant and Doherty 2009, p. 511). Available information in the scientific Program, aerial spraying is conducted Additionally, most of the OHV activity literature regarding the effects of infrequently in the Imperial Valley— in the region occurs during the cooler malathion, a broad-spectrum aerial treatments have been necessary times of the year (Wone 1992, pp. 4–5), insecticide, on lizard species are only twice in the 9 years prior to the suggesting that fewer flat-tailed horned equivocal, with some suggesting that 2007 environmental assessment (BLM lizards would be on the surface during malathion has substantial deleterious 2007b, p. 9). Additionally, the State’s peak times of OHV activity. effects on lizards (such as O¨ zelmas and program administrator for the Curly Top Moreover, the density of flat-tailed Akay 1995, pp. 730–737; Khan 2003, pp. Virus Control Program indicated that horned lizards is apparently naturally 821–825; Khan 2005, pp. 77–81), and although the program will continue in low. Even at the highest estimated others suggesting the effects are less the region, the frequency of aerial density of 4.4 adult flat-tailed horned pronounced (such as Holem et al. 2006, treatments in the foreseeable future is lizards per hectare (1.8 per acre) (see pp. 111–116; Holem et al. 2008, pp. 92– anticipated to decrease; instead, Background), which is equivalent to 98). We are not aware of any studies treatments are more likely to be 0.00044 individuals per square meter examining the effects of malathion on implemented via ground-based spraying (0.00004 per square foot), the chances of horned lizard species. in areas near agriculture outside of flat- a flat-tailed horned lizard being run over Flat-tailed horned lizards are tailed horned lizard habitat (R. Clark, by a vehicle is low, even in areas of high insectivorous, primarily feeding on California Department of Food and OHV activity (for example, see Nicola harvester ants. If the food source for the Agriculture, pers. comm., 2010). and Lovich 2000, pp. 208–212). flat-tailed horned lizard is substantially Because of the avoidance and Nevertheless, mortality of flat-tailed affected by the spraying of malathion, minimization measures incorporated horned lizards resulting from OHV the flat-tailed horned lizard could be into the Curly Top Virus Control activity has been documented, even in affected. To address this concern, Program, and because of the likely areas of low OHV use. For example, in implementation of the Curly Top Virus limited effects to the flat-tailed horned an area closed to OHV traffic, 2 of the Control Program in the Imperial Valley lizard and its food source at the levels 42 radio-tagged flat-tailed horned in 1991 included monitoring of that the program is expected to be lizards were killed by illegal OHV harvester ant colonies. Results showed implemented, we conclude that activity, and 1 was killed by a vehicle malathion killed worker ants on the implementation of the Curly Top Virus on a paved road (Muth and Fisher 1992, surface at the time of the spraying, Control Program is not a threat to the pp. 18 and 33). However, in negatively affecting ant colonies flat-tailed horned lizard. comparison, in that same study, 16 of temporarily; however, it also showed Vehicle Activity the 42 radio-tagged flat-tailed horned that the colonies, with the queen and lizards were depredated over the same other workers below ground, rapidly Flat-tailed horned lizards may be period (Muth and Fisher 1992, p. 33). recovered (Peterson in litt. 1991, p. 10; directly affected by vehicle activity. The In the past, OHV activity along the see also BLM 2007b, p. 75). Although assessments in the 1993 and 2003 United States-Mexico boundary (border) that monitoring was cursory, the documents (58 FR 62624 and 68 FR 331, from Border Patrol activity and other information suggests that spraying is not respectively) identified impacts from border-related OHV traffic has been likely to substantially affect the primary vehicles as a threat to the species, specifically identified as a threat. food source of the flat-tailed horned especially OHV activity. Impacts of Border-related OHV activity is part of lizard now or in the foreseeable future. vehicle activity on flat-tailed horned our definition of OHV activity and is Even if flat-tailed horned lizards or lizard habitat are addressed in Factor A, covered above. Moreover, since 2008, harvester ants are affected by malathion, above. Additionally, individual flat- the U.S. Customs and Border Protection the Curly Top Virus Control Program tailed horned lizards may be killed— constructed the ‘‘border fence,’’ which is includes measures to limit its impact. crushed—by vehicle activity. As a vehicle and, in some areas, pedestrian The threat from pesticide spraying has discussed above, because flat-tailed barrier, plus associated infrastructure, in been reduced by avoidance and horned lizards are unlikely to flee from certain areas between the United States minimization measures incorporated in oncoming traffic, when flat-tailed and Mexico. Although some areas of the the program since the publication of the horned lizards are on paved roadways border are not fenced, the areas of flat- 1993 proposed rule to list the flat-tailed they are likely to be killed by any tailed horned lizard habitat along the horned lizard, including the following vehicle activity. Additionally, flat-tailed border are fenced (USCBP 2008a, p. 1– (BLM 2007b, p. 33): horned lizards may be killed by vehicles 5; USCBP 2008b, p. 2–4; Rorabaugh (1) No malathion treatments shall operating off paved roads, including 2010, p. 181). Evidence suggests the occur in designated flat-tailed horned vehicle activity on established dirt or border fence has reduced illegal cross- lizard Management Areas as set forth in gravel roads and trails, or vehicle border traffic and associated OHV the Flat-tailed Horned Lizard Range- activity off established roads and trails activity (Rorabaugh 2010, p. 190), wide Management Strategy. (OHV activity as defined in Factor A) thereby reducing the amount of

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potential impacts to flat-tailed horned drought to be a significant threat to the disproportionately promote growth of lizards along the border from illegal species throughout its range. nonnative, invasive plant species, trans-border OHV activity and Current climate change predictions which can increase the prevalence of subsequent law-enforcement OHV for terrestrial areas in the Northern wildland fire and be a physical activity by the Border Patrol. Hemisphere indicate warmer air hindrance to flat-tailed horned lizard Because the flat-tailed horned lizard temperatures, more intense locomotion (see ‘‘Invasive, Nonnative occurs naturally in low densities, roads precipitation events, and increased Plants’’ section in the Factor A are generally widely separated, and summer continental drying (Field et al. discussion, above). OHV activity is only intense in a few 1999, pp. 1–63; Cayan et al. 2006, pp. Thus, the effects associated with areas, the chances that a flat-tailed 1–47; Meehl et al. 2007, pp. 747–843). global climate change may affect the horned lizard being crushed by vehicle Assessments for the Sonoran Desert are flat-tailed horned lizard, but at this activity is low over the majority of the few, but the region is expected to warm time, the level of uncertainty in climate species’ range; therefore, we conclude (IPCC 2007, p. 887). Indeed, since about predictions is high. Moreover, we do not that vehicle activity is not a substantial the 1970s, the region appears to have know whether such a change would threat to the species throughout its experienced ‘‘widespread warming substantially affect the flat-tailed horned range, nor do we expect it to become a trends in winter and spring, decreased lizard. While we recognize that climate significant threat in the foreseeable frequency of freezing temperatures, change is an important issue with future. lengthening of the freeze-free season, potential effects on species and their and increased minimum temperatures habitats, we lack adequate information Drought and Climate Change per winter year’’ (Weiss and Overpeck to make accurate predictions regarding The assessments in the 1993 and 2003 2005, p. 2065). Further, if summertime its effects to the flat-tailed horned documents (58 FR 62624 and 68 FR 331, temperatures increase in the already lizard. We do not have any evidence to respectively) included drought as a typically hot Sonoran Desert, suggest that the flat-tailed horned lizard potential threat to the flat-tailed horned temperatures may exceed the ability for is being substantially affected by climate lizard. Additionally, changes in weather many animals, including the flat-tailed change at this time, or will be within the patterns associated with global climate horned lizard, to survive. For example, foreseeable future. Therefore, the effects change, particularly the timing and Sinervo et al. (2010, p. 895) suggest that of climate change are not a significant amount of rainfall in this arid region, Phrynosomatid lizards (the family to threat at this time. which flat-tailed horned lizards belong) are a potential threat to the species. We Summary of Factor E Threats are susceptible to increased risk of examine both below. extinction because of their intolerance For Factor E, we assess the natural Prolonged periods of atypically low to an increase in environmental and manmade threats that affect the rainfall (drought) may potentially affect temperatures. Increased temperatures status of the species. Small populations flat-tailed horned lizard by affecting its would result in longer periods of time may be disproportionately affected by food chain (see Background section). when the flat-tailed horned lizard extrinsic and intrinsic factors that Plants produce fewer seeds during would be forced to seek cooler reduce population size. Given that periods of low rain, leading to a microclimates (shade, burrows), leaving historical agricultural and urban reduction in the number of foraging ants less time available in the day for feeding development destroyed large swaths of (Tevis 1958, p. 698), which reduces the or other necessary activities (see also potential flat-tailed horned lizard amount of food available for flat-tailed Huey et al. 2010, pp. 832–833). habitat, we assessed whether the horned lizards. However, harvester ant However, we are not aware of any remaining populations are large enough colonies do appear to survive prolonged information indicating that the flat- to likely avoid the deleterious effects periods of drought (Tevis 1958, p. 701; tailed horned lizard is being associated with small populations. Whitford et al. 1999, p. 165), indicating substantially affected by a reduced Within the Coachella Valley Population that flat-tailed horned lizards will have frequency of cold temperatures or area, where habitat destruction has some food available. Depressed flat- increased frequency of high continued (see Factor A), flat-tailed tailed horned lizard populations temperatures, or that it will be horned lizards are now found only in associated with reduced abundance of substantially affected in the foreseeable two small locations and may be more ants are known to have rebounded after future. likely to be affected by the deleterious ant populations returned, even in small Additionally, precipitation may effects associated with small populations of flat-tailed horned lizards become more variable (Weiss and populations. Using conservative (Barrows and Allen 2009, p. 314). Thus, Overpeck 2005, p. 2065). Increased estimates of flat-tailed horned lizard we do not expect droughts to severity, frequency, or duration of density in combination with the size of permanently affect large populations of droughts may exceed the resiliency of the Western, Eastern, and Southeastern flat-tailed horned lizards, although the flat-tailed horned lizard, or the Populations areas (as a whole), we droughts may contribute to the species in the food chain upon which it conclude that each is large enough to extirpation of small populations. depends. In contrast, models suggest support populations that are not likely Because about 91 percent of the area that the frequency and intensity of El to be affected by the deleterious effects occupied by flat-tailed horned lizards Nin˜ o-Southern Oscillation events may associated with small populations. are in areas large enough to support increase as a result of global climate However, the Western, Eastern, and large populations (see ‘‘Barriers and change (Field et al. 1999, p. 10), which Southeastern Populations areas have Small Populations’’ section above), and may lead to increased rainfall in some within them potential manmade barriers because evidence shows that even small portions of the species’ range. Although (canals, roads, railways) that may populations of flat-tailed horned lizards typically considered a benefit, increased further act as complete barriers or have survived periods of drought (see rainfall may negatively affect harvester semipermeable barriers that subdivide above), this suggests that it is not likely ant abundance and thus negatively the populations into smaller that all of the 9 percent of the ‘‘small affect flat-tailed horned lizards, at least subpopulations. Thus, we assessed population’’ area would be affected by in some areas (Barrows and Allen 2009, whether the areas created by these drought. Therefore, we do not anticipate p. 312). Also, increased rainfall may potential barriers were large enough to

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likely support populations either individually or in combination. infrastructure (USCBP 2008b, p. ES–1), (subpopulations) that were likely greater Therefore, based on our review of the including certain conservation measures than 7,000 adult individuals. Using the best available scientific and commercial from the Rangewide Management most conservative flat-tailed horned information we find the flat-tailed Strategy that will be implemented to the lizard density estimate of 0.3 individual horned lizard is not threatened by fullest extent applicable and practicable. adults per hectare (0.1 per acre), which natural or manmade factors affecting its Thus, implementation of the is the lowest value in the range of continued existence, either now or in Environmental Stewardship Plans is estimates that extends to 4.4 individuals the foreseeable future. best considered a conservation effort for per hectare (1.8 per ac), and assuming the species. Conservation Efforts (1) all potential barriers are complete Finding barriers, which is unlikely because some Before we may determine whether a barriers likely allow some movement of species should be listed as endangered The flat-tailed horned lizard individuals (see above) and only 1 to 10 or threatened, section 4(b)(1)(A) of the monitoring data on which we relied in individuals per generation are needed to Act requires that we take into account this document are more robust than the maintain population connectivity; and those efforts, if any, being made by any data we relied on in our 1993 proposed (2) 7,000 adults is the threshold above State or foreign nation, or any political rule (58 FR 62624) and our earlier which a population is large enough to subdivision of a State or foreign nation, withdrawal documents (62 FR 37852, 68 likely avoid the deleterious effects to protect the flat-tailed horned lizard. FR 331, and 71 FR 36745), thus enabling associated with small populations, Of particular note is the Interagency us to conclude with increased which is at the high end of the range of Conservation Agreement between and confidence that flat-tailed horned lizard estimated population thresholds, we among participating State and Federal populations in the Management Areas concluded that about 83 percent, 73 agencies implementing the Rangewide are not low in abundance or declining. percent, and 97 percent of the Western, Management Strategy, which is Although no comparable historical Eastern, and Southeastern Population discussed in detail in the Background abundance data exist, our analysis areas (respectively), and about 91 section. Other conservation efforts suggests that occupancy of flat-tailed percent of the area overall, are in large include regulatory mechanisms, which horned lizards within survey areas is enough blocks that the populations of are discussed under Factor D in the relatively high. Density estimates flat-tailed horned lizards within them Summary of Factors Affecting the obtained through the new survey are not likely to be affected by threats Species section. methodology are roughly in the same associated with small populations. On April 3, 2008, the Secretary of the range provided by previous estimates, Thus, the vast majority of the current U.S. Department of Homeland Security suggesting no marked declines in distribution of the flat-tailed horned (DHS), pursuant to his authority under density since the late 1990s. Although lizard occurs in blocks of habitat large section 102(c) of the Illegal Immigration additional surveys are needed before the enough to support populations greater Reform and Immigrant Responsibility recently collected data can provide than 7,000 adults; therefore, small Act (8 U.S.C. 1103 note) (IIRIRA), long-term trend information, the short- population size is not a threat to the flat- exercised his authority to waive certain term data do not currently indicate tailed horned lizard and the species is environmental and other laws in order declines. Because of data limitations, we not habitat-limited. to ensure the expeditious construction cannot extrapolate the data rangewide; Pesticide spraying associated with the of tactical infrastructure along the however, for the Management Areas Curly Top Virus Control Program is not United States-Mexico Border (i.e., the surveyed (see Population Dynamics a threat to the flat-tailed horned lizard ‘‘border fence’’) (73 FR 18293). As such, under the Background section), the best because of the small area within the activities associated with construction available scientific information suggests range of the species over which it is and operation of the border fence are that population levels are not low and likely to occur, the avoidance and exempt from regulatory mechanisms not declining. In other words, minimization measures built into the described in Factor D. These activities recognizing that the areas surveyed program, and the likely limited effects also do not need to comply with the compose only a fraction of the overall of spraying on the flat-tailed horned avoidance, minimization, or mitigation range of the flat-tailed horned lizard, it lizard and its harvester ant food source. measures described in the Rangewide is our interpretation that the available Additionally, vehicle activity—on Management Strategy. However, the population data (alone and without paved roads, non-paved roads, and off- Secretary committed DHS to continue to considering potential threats) do not road—is not a substantial threat to the protect valuable natural and cultural support a conclusion that the species is species because the chances of a flat- resources (USCBP 2008a, p. ES–1). As a in danger of extinction. Additionally, tailed horned lizard being crushed by result, the U.S. Customs and Border despite the lack of long-term trend data, vehicle activity are low over the Protection prepared Environmental the general agreement of the recent data majority of the species’ range. Drought Stewardship Plans for the portions of with the older data from the available is also not likely to be a substantial the United States-Mexico border that scientific literature lead to our threat to the species throughout its fall within the current distribution of interpretation that the available range. Climate change could potentially the flat-tailed horned lizard (USCBP population data (alone and without affect flat-tailed horned lizards, but the 2008a, 2008b, entire documents). United considering potential threats) do not future effects of climate change are States Customs and Border Protection support a conclusion that the species is uncertain. Moreover, no substantial has expressed an intent to work in a likely to become endangered within the effects of climate change to the flat- collaborative manner with local foreseeable future. tailed horned lizard are known at this government, State and Federal land Although our past assessments time. Therefore, the effects of climate managers, and the interested public to suggest that historical loss of habitat change are not a significant threat at this identify environmentally sensitive resulted in artificial barriers, except for time. resources and develop appropriate best the Coachella Valley Population, the We do not consider the potential management practices to avoid or information currently available indicate threats analyzed above to be substantial minimize adverse impacts resulting otherwise. We conclude that the threats to the flat-tailed horned lizard, from the installation of tactical manmade barriers resulting from

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historical agricultural and urban to the 467,000 ha (1,154,000 ac) of the signatory lands, particularly within development merely expanded pre- U.S. portion of that range, and the Management Areas. Additionally, existing natural barriers. This threats to the Coachella Valley threats to the species and its habitat in conclusion is based on genetic data that population do not substantially threaten areas outside of the Management Areas show separation of the Western, Eastern, the species as a whole. are likely restricted by the limited and Southeastern Populations occurred Therefore, the effects to the species amount of water available in this arid prior to the development of the region associated with the implied meaning of region and remoteness of much of the more than a century ago. Genetic data fragmentation—that is, the division of habitat, especially in Mexico. Less also suggest that flat-tailed horned the species’ populations into smaller remote areas, such as the Coachella lizards in the Coachella Valley had populations by the introduction of Valley, Borrego Springs, Yuma, San Luis limited connection with the Western manmade barriers and the subsequent de Colorado, and Puerto Pen˜ asco areas, Population; thus, the historical deleterious effects that may be are more likely to have urban or agricultural development northwest of associated with small population size— agricultural development; however, the Salton Sea, along with the continued are not likely to constitute a substantial impacts in these areas are anticipated to development in that region, has created threat to the species now or within the be small relative to the amount of an artificial barrier at this location. As foreseeable future. available habitat throughout the species’ such, the treatment of flat-tailed horned Within the United States, most of the current distribution. lizards in the Coachella Valley as a area occupied by the species is under Development associated with new separate population is more an artifact Federal or State control and overseen by energy facilities is likely to be reduced of manmade activities than of natural agencies that are signatories to the or limited by continued implementation divisions within the flat-tailed horned Interagency Conservation Agreement of the Rangewide Management Strategy. lizard population as a whole. and associated Rangewide Management Although few energy development Moreover, we determined herein that Strategy. Although the Interagency projects have been fully permitted to the Western, Eastern, and Southeastern Conservation Agreement is voluntary, date, we anticipate more will be Population areas (each as a whole) are several signatories—including the BLM, proposed in the foreseeable future. not threatened by the factors associated which is a major landowner within the Within the range of the flat-tailed with small population size and are not U.S. portion of the range of the flat- horned lizard, we expect development habitat-limited. Thus, ramifications of tailed horned lizard—have incorporated within the Western Population between historical habitat loss are not likely to aspects of the Rangewide Management Interstate 8 and the existing railway constitute a significant threat to the Strategy into their planning documents, (Part W–5) to reduce the already limited species within the foreseeable future in thus making them less voluntary connectivity across Interstate 8, these populations. Additionally, because those plans implement existing although South Fork Coyote Wash is because the majority of the Western, regulatory mechanisms. Implementation expected to continue to be a potential Eastern, and Southeastern Population of this strategy resulted in creation of corridor for flat-tailed horned lizard areas are not subdivided by other five Management Areas that, as of 2009, movement. We conclude the remaining barriers (such as canals, roads, railways, total 185,653 ha (458,759 ac) of higher habitat in the Western Population area or border infrastructure), it is unlikely quality flat-tailed horned lizard habitat (i.e., north of the railway and south of these areas would be substantially (Table 1). Management objectives also Interstate 8, including areas designated affected by the intrinsic and extrinsic provide avoidance and minimization as Management Areas) is large enough factors, including edge effects, that may measures to reduce impacts from to support flat-tailed horned lizard negatively affect small populations. permitted projects and limit the populations. Also, we expect the total In the Coachella Valley, the precise development area within each acreage of potential development for amount of habitat that is occupied is not Management Area to 1 percent. renewable energy facilities to be small known, but based on an analysis of Additionally, implementation of the compared to the overall range of the habitats within the Coachella Valley Rangewide Management Strategy calls species, including on private land. MSHCP plan, the Thousand Palms and for monitoring, management, land Additionally, on lands managed by Dos Palmas reserves are anticipated to acquisition, and research; further, it signatory agencies to the Interagency be 1,707 ha (4,219 ac) and 2,078 ha promotes coordination with Conservation Agreement, we expect the (5,134 ac), respectively (see Table 2). Of governmental and non-governmental impacts to flat-tailed horned lizard these, 94 percent of the Thousand Palms groups in Mexico to provide habitat (whether inside or outside of reserve is already in protected status, conservation benefit for the species in designated Management Areas) will be while 34 percent of the Dos Palmas that country. The tasks identified by the further reduced because of the reserve is protected (Table 2). These two Rangewide Management Strategy have avoidance, minimization, and small areas are unlikely to support flat- been consistently implemented by compensation measures of the tailed horned lizard populations large signatory agencies per the Rangewide Rangewide Management Strategy. enough to escape from being Management Strategy’s schedule. Thus, Additionally, invasive, nonnative substantially affected by the intrinsic we conclude the conservation efforts plants; vehicle activity, including OHV and extrinsic factors, including edge implemented by signatories of the use near the United States-Mexico effects, that may negatively affect small Interagency Conservation Agreement border and elsewhere; and pesticide populations. However, even if the and associated Rangewide Management spraying are not likely substantial Coachella Valley Population may be Strategy reduce the impact of existing threats to the species throughout its threatened by the effects of barriers and threats in the United States and promote range. Predation is not likely a the intrinsic and extrinsic factors that actions that benefit the flat-tailed substantial threat in and of itself, but may negatively affect small populations, horned lizard throughout its range, because several species that prey upon the 3,785-ha (9,353-ac) Coachella Valley including Mexico. flat-tailed horned lizards likely occur in Population area makes up only about Threats to flat-tailed horned lizards higher numbers near manmade areas, 0.2 percent of the roughly 1,585,000 ha associated with development activities predation may contribute to the (3,916,600 ac) of the rest of the species’ are reduced or limited by the deleterious effects (as an ‘‘edge effect’’) range and about 0.8 percent compared Interagency Conservation Agreement on associated with urban and agricultural

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development and increase the level of species (i.e., the species as a whole, Coachella Valley population is impermeability of some semipermeable including any and all taxonomically biologically or ecologically significant barriers. However, we do not expect defined subspecies) but also any pursuant to the [DPS policy], we may increased levels of predation to (individual) subspecies and any distinct reconsider the status of the Coachella substantially affect the species where it population segment (DPS) of a Valley population for the purpose of occurs in large ‘‘parts,’’ which is a vertebrate species (16 U.S.C. 1532). On listing under the Act’’ (68 FR 336). majority of its range overall and within February 7, 1996, we, along with the Since then, additional information the Western, Eastern, and Southeastern National Marine Fisheries Service has become available on the genetic Populations. Drought and climate (National Oceanic and Atmospheric structure of flat-tailed horned lizard change have the potential to affect flat- Administration—Fisheries), finalized a populations. Genetic data could, as tailed horned lizards, but the magnitude joint policy that addresses the indicated by the DPS policy (61 FR of this threat, although unclear because recognition of DPSs of vertebrate species 4725), inform our analysis of of the high level of uncertainty for potential listing actions (DPS policy) associated with climate predictions, do (61 FR 4722). The policy was developed discreteness or significance. Therefore, not appear to be significant now or (1) to implement the measures in light of this new information and our within the foreseeable future. prescribed by the Act and Congressional past DPS analysis, we believe it is Finally, we acknowledge we lack guidance, (2) to allow for a more refined appropriate to evaluate potential DPSs complete population data for the species application of the Act to better reflect of the flat-tailed horned lizard. throughout its range. However, through the biological needs of the taxon being The 1996 DPS policy specifies that we our analysis of size of the habitat areas, considered, and (3) to avoid the should address two elements prior to and application of conservative inclusion of entities that do not require determining a population segment’s estimates (smallest density value within protective measures of the Act. As noted conservation status in relation to the the estimated range, and largest in the policy (61 FR 4725), Act’s standard for listing (61 FR 4725). population size value below which a Congressional guidance indicates that These include: (1) The population population may be considered ‘‘small’’), the authority to list DPSs is to be used segment’s discreteness from the we conclude that the flat-tailed horned ‘‘sparingly.’’ remainder of the species to which it lizard populations are not small and the As mentioned previously, we belongs, and (2) the population species is not habitat-limited in the proposed to list the flat-tailed horned segment’s significance to the species to United States or Mexico at this time, nor lizard—the entire species throughout its which it belongs. If we determine that do we expect the species to suffer from range—as a threatened species under a population segment meets the the deleterious effects of small the Act in 1993 (58 FR 62624). Since discreteness and significance standards, population size in the foreseeable then, we conducted several additional then we evaluate the level of threat to future. analyses on the status of the species. that population segment based on the As required by the Act, we considered From the 1993 proposed rule through five listing factors established by section the species’ status relative to one or the 2006 withdrawal document (71 FR 4(a) of the Act to determine whether more of the five factors described in 36745), we noted the disjunct listing the DPS as either endangered or section 4(a)(1) of the Act, and the distribution of the species. Our 2003 threatened is warranted. standards for listing as endangered or withdrawal document in particular threatened throughout all of its range, explicitly addressed threats over four As described in Description of and we considered the conservation disjunct populations of the flat-tailed Specific ‘‘Populations’’ in the efforts being made by any State or horned lizard that we identified in the Background section above, the foreign nation. We have carefully United States, including: (1) The distribution of the flat-tailed horned assessed the best scientific and Coachella Valley in California, (2) the lizard may be divided into four, commercial data available regarding the area west of the Salton Sea and Imperial physically (geographically) separated past, present, and reasonably Valley in California, (3) the area east of populations. Below, we evaluate these anticipated future threats faced by this the Salton Sea and Imperial Valley in populations as potential distinct species. Our analysis of the information California, and (4) the Yuma Desert area vertebrate population segments under pertaining to the five threat factors did in Arizona (68 FR 331). Additionally, our DPS policy. not identify threats of imminence, we addressed separately the populations Discreteness intensity, or magnitude, either in Mexico. individually or in combination, to the Also in our 2003 withdrawal Our DPS policy states that a vertebrate extent that the species requires the document, we conducted a brief population segment may be considered protection of the Act throughout its evaluation of a potential DPS for the discrete if it satisfies either of the range. Further, there is no information Coachella Valley population (and only following two conditions (61 FR 4725): to suggest that the flat-tailed horned that population) in a response to a (1) It is markedly separated from other lizard population is declining or is in public comment (68 FR 336). We populations of the same taxon as a danger of becoming an endangered alluded to the population possibly being consequence of physical, physiological, species in the foreseeable future. discrete (because it was disjunct), but ecological, or behavioral factors. Therefore, we conclude that the species we concluded that it was not significant Quantitative measures of genetic or is not in danger of extinction or likely within the meaning of the DPS policy morphological discontinuity may to become so within the foreseeable because: (1) It was not ‘‘genetically, provide evidence of this separation; or future and is not in need of the behaviorally, or ecologically unique’’; (2) protections afforded by the Act at this it was not a ‘‘large population’’ (not (2) It is delimited by international time. necessarily as defined in the present governmental boundaries within which document); and (3) it did not contribute differences in control of exploitation, Distinct Population Segment ‘‘individuals to other geographic areas management of habitat, conservation Under section 3(16) of the Act, a through emigration.’’ Our response status, or regulatory mechanisms exist ‘‘species’’ is defined as including not concluded, ‘‘If additional information that are significant in light of section only the full, taxonomically defined becomes available that indicates the 4(a)(1)(D) of the Act.

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First Condition for Discreteness mechanisms between the United States lizards in the Thousand Palms and Dos As noted at various points in the and Mexico. Below, we present a brief Palmas subareas also meet the Background section, each of the four synopsis of these four categories, discreteness element of the 1996 DPS described populations—the Coachella combining the last two. Please refer to policy under the first condition for Valley, Western, Eastern, and the Summary of Factors Affecting the discreteness. None of the population Southeastern Populations—are Species and Findings sections of this segments that cross the United States- geographically separated from each document for additional details. Mexico boundary meet the second • Control of exploitation: We have no other by natural barriers, manmade condition for discreteness. information suggesting that the flat- barriers, or both. The four populations tailed horned lizard is significantly Significance of flat-tailed horned lizards are exploited on either side of the border If a population segment is considered markedly separated from each other as (see the discussion under Factor B). discrete under one or more of the a consequence of physical factors and • Management of habitat: conditions described in our DPS policy, each may be readily circumscribed and Management of flat-tailed horned lizard its biological and ecological significance distinguished from the others. habitat is essentially the same in the will be considered in light of Therefore, the four populations of flat- United States and in Mexico, although Congressional guidance that the tailed horned lizards meet the first the underlying mechanisms differ. For authority to list DPSs be used condition for discreteness under our example, in the United States large areas ‘‘sparingly,’’ while encouraging the DPS policy. are protected as Management Areas conservation of genetic diversity. In Additionally, the Coachella Valley through implementation of the making this determination, we consider Population, although more extensive in Rangewide Management Strategy, and available scientific evidence of the the recent past, now consists of two in Mexico large areas are protected as discrete population segment’s isolated occurrences, the Thousand National Parks and Biosphere Reserves importance to the taxon to which it Palms and Dos Palmas subareas. In the (see the discussion under Factor A). belongs. Because precise circumstances Summary of Factors Affecting the • Conservation status and regulatory are likely to vary considerably from case Species section, we considered the mechanisms: In terms of actual to case, the DPS policy does not Thousand Palms and Dos Palmas designations of listing under the two describe all the classes of information subareas together as the Coachella countries’ respective species-protection that might be used in determining the Valley Population because both had the laws, the conservation status differs biological and ecological importance of potential to share similar threats due to between the United States and Mexico. a discrete population. However, the DPS proximity, and both were covered by the In the United States, as a result of this policy does provide four possible Coachella Valley MSHCP. However, as withdrawal, the species is not listed; in reasons why a discrete population may noted, the genetic affinities of the Dos Mexico, it is listed as a threatened be significant. As specified in the DPS Palmas subareas are not known. Thus, species under the Official Mexican policy (61 FR 4722), this consideration combining the Thousand Palms and Dos Norm NOM–059–ECOL–2001 of the population segment’s significance Palmas subareas into the Coachella (SEMARNAT 2002, p. 134). However, in may include, but is not limited to, the Valley Population was a grouping of the United States, existing conservation following four conditions (61 FR 4725): convenience, adequate for evaluating efforts and regulatory mechanisms (1) Persistence of the discrete threats, but not necessarily for assessing reduce the magnitude of potential population segment in an ecological the population segments as potential threats to the species to a point where setting unusual or unique for the taxon, DPSs. Thus, we consider the Thousand protections afforded by the Act are not (2) Evidence that loss of the discrete Palms and Dos Palmas subareas necessary (see the discussion under population segment would result in a separately in our assessment of Factor D and the Findings and significant gap in the range of the taxon, significance for the Coachella Valley Conservation Efforts sections). (3) Evidence that the discrete Population. These two occurrences are We conclude the second condition is population segment represents the only markedly separated from each other and not satisfied because no significant surviving natural occurrence of a taxon from the other populations of flat-tailed differences exist with respect to the flat- that may be more abundant elsewhere as horned lizards as a consequence of tailed horned lizard across the an introduced population outside its physical factors (geographical international boundary between the historic range, or separation); therefore, each meets the United States and Mexico. As such, the (4) Evidence that the discrete first condition for discreteness under Western, Eastern, and Southeastern population segment differs markedly our DPS policy. Populations described above are from other populations of the species in Second Condition for Discreteness discrete in themselves and not with its genetic characteristics. respect to the international boundary A population segment needs to satisfy The Western, Eastern, and between the United States and Mexico. only one of these criteria to be Southeastern Populations extend across considered significant. Furthermore, the Conclusion for Discreteness per 1996 the international border with Mexico; as list of criteria is not exhaustive; other DPS Policy a result, each of these three populations criteria may be used as appropriate. could potentially be further divided into We conclude that each of the four Below, we assess whether the four separate population segments under the population segments analyzed (Western, discrete populations defined above are policy’s second condition for Eastern, Southeastern, and Coachella significant per our DPS policy. discreteness. Valley) meets the discreteness element First Condition—Persistence of the Application of the second condition of the 1996 DPS policy because each can discrete population segment in an for discreteness (61 FR 4725) with be considered markedly separated from ecological setting unusual or unique for respect to the flat-tailed horned lizard the other flat-tailed horned lizard the taxon. tests for significant differences in: (1) populations as a consequence of None of the four primary populations The control of exploitation, (2) the physical factors (first condition for of flat-tailed horned lizard occurs in an management of habitat, (3) the discreteness). Within the Coachella ecological setting unusual or unique for conservation status, or (4) the regulatory Valley Population, flat-tailed horned the species. Although the ecological

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setting varies across and within the the source for much of the sand over a of the species because each of these range of the four populations, important large portion of the range of the species population segments represents a ecological characteristics are similar (see Setting and Habitat in the relatively large portion of the total range among the four populations (see Background section). However, the of the species (Table 6). In contrast, the Background section). Climatic range of the flat-tailed horned lizard range of the Coachella Valley conditions across the range of the four includes other areas where soils are Population as a whole, or the separate populations are characterized by hot derived from sedimentation from the Thousand Palms or Dos Palmas summer temperatures, mild winter surrounding areas, particularly the subareas, is very small relative to the temperatures, and little rainfall. Across western edge of the Western Population total range of the species. The range of the four populations, flat-tailed horned where it meets lower extremities of the the Coachella Valley Population lizards are associated with creosote- Peninsular Range (see Setting and represents only 0.24 percent of the total white bursage plant associations in Habitat in the Background section). range of the species (0.80 percent of the areas characterized as sandy flats or Thus, evidence indicates this difference U.S. portion of the range) (Table 6). The valleys (see Setting and Habitat in the in substrate does not translate into an range of the Thousand Palms population Background section). ecological setting unusual or unique for represents only 0.11 percent of the total The ecological setting for the the flat-tailed horned lizard. We range of the species, and the range of the Coachella Valley Population as a whole, conclude that none of the four Dos Palmas population represents only or the Thousand Palms and Dos Palmas population segments meets the first 0.13 percent of the species’ total range subareas separately, are not markedly significance condition. (Table 6). Loss of the Coachella Valley unusual or unique. The arenaceous Second Condition—Evidence that loss population segment would not result in (sandy) soils that support flat-tailed of the discrete population segment a significant gap in the range of the horned lizards in the Coachella Valley would result in a significant gap in the species. We conclude that the Western, are derived from the surrounding areas range of a taxon. Eastern, and Southeastern population and are compositionally different from Loss of the Western, Eastern, or segments meet the second significance those deposited by the Colorado River Southeastern population segment would condition, but the Coachella Valley (van de Kamp 1973, p. 827), which is result in a significant gap in the range population segment does not.

TABLE 6—SIZE (AREA) OF THE POPULATIONS UNDER CONSIDERATION TO BE POTENTIAL DISTINCT VERTEBRATE POPU- LATION SEGMENTS UNDER THE ACT. THE THOUSAND PALMS AND DOS PALMAS OCCURRENCES ARE SUBSETS OF THE COACHELLA VALLEY POPULATION (SEE DESCRIPTION OF SPECIFIC ‘‘POPULATIONS’’ IN THE BACKGROUND SECTION FOR DETAILS).

Total range of species U.S. portion of range only Population Percent of Percent of Size (area) 1 1 total Size (area) total

Western ...... 341,989 ha (845,073 ac) ...... 21.52 253,020 ha (625,226 ac) ...... 53.74 Eastern ...... 169,617 ha (419,133 ac) ...... 10.67 146,121 ha (361,073 ac) ...... 31.03 Southeastern ...... 1,073,551 ha (2,652,802 ac) ...... 67.56 67,922 ha (167,839 ac) ...... 14.43 Coachella Valley ...... 3,785 ha (9,353 ac) ...... 0.24 3,785 ha (9,353 ac) ...... 0.80 (Thousand Palms sub- 1,707 ha (4,219 ac) ...... 0.11 1,707 ha (4,218 ac) ...... 0.36 area). (Dos Palmas subarea) 2,078 ha (5,134 ac) ...... 0.13 2,078 ha (5,135 ac) ...... 0.44

Total ...... 1,588,942 ha (3,926,361 ac) ...... 100.00 470,848 ha (1,163,491 ac) ...... 100.00 1 Area values are estimated through a GIS-based assessment. Despite the level of precision presented, area values are approximate; how- ever, we believe they are accurate enough to draw the conclusions presented.

Third Condition—Evidence that the significantly genetically differentiated haplotypes unique to flat-tailed horned discrete population segment represents from each other (Mulcahy et al. 2006, lizards from the Thousand Palms the only surviving natural occurrence of pp. 1807–1826; Culver and Dee 2008, occurrence within the Coachella Valley a taxon that may be more abundant pp. 1–14). Thus, the evidence indicates Population have been found, genetic elsewhere as an introduced population that the Western, Eastern, and differences between these lizards and outside its historic range. Southeastern Populations of flat-tailed Western Population lizards were not Populations of the flat-tailed horned horned lizards differ markedly from statistically significant (Mulcahy et al. lizard have not been introduced outside each other in their genetic 2006, p. 1811 and p. 1817). Although the species’ historic range, so none of characteristics. Coachella Valley flat-tailed horned the four population segments meets the However, evidence shows that the lizards are currently markedly separated third significance condition. Thousand Palms subarea (occurrence) geographically from other flat-tailed Fourth Condition—Evidence that the within the Coachella Valley Population horned lizard populations as a result of discrete population segment differs is not markedly different from the isolation due to past agricultural and markedly from other populations of the Western Population in its genetic urban development, genetics species in its genetic characteristics. characteristics, although the Thousand information suggests that the flat-tailed As described in Populations and Palms occurrence within the Coachella horned lizards in the Thousand Palms Genetics in the Background section, the Valley Population, like the Western occurrence were historically not Western, Eastern, and Southeastern Population, is genetically significantly separated from Western Population flat- Populations are genetically cohesive different from the Eastern and tailed horned lizards (Mulcahy et al. populations within themselves but are Southeastern Populations. Although 2006, p. 1821). Thus, the evidence

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indicates that the population of flat- indicates that each of these three were significant at the scale of flat-tailed tailed horned lizards in the Thousand population segments differs markedly in horned lizard across its entire range, as Palm occurrence within the Coachella genetic characteristics from the other well as whether any of the threats were Valley Population does not differ populations of flat-tailed horned lizards significant at the scale of the four major markedly from the Western Population (fourth significance condition). In populations (see Summary of Factors in its genetic characteristics. considering the importance of the Affecting the Species section). We are not aware of any genetic Coachella Valley Population (the For Factor A, we identified and information on the Dos Palmas subarea Thousand Palms and the Dos Palmas evaluated habitat threats from (occurrence). [We believe the map occurrences together) or the Thousand agricultural development, urban shown by Culver and Dee (2008, Figure Palms and the Dos Palmas occurrences development, energy development, 1, p. 14) to be in error because they used separately to the species as a whole, we invasive and nonnative plants, OHVs, the same samples for the Coachella determined that neither the Coachella and military training activities. This Valley Population that Mulcahy et al. Valley Population, the Thousand Palms analysis led us to conclude that none of (2006) used (Culver and Dee 2008, p. 4), occurrence, nor the Dos Palmas these potential habitat threats, either which indicated that genetic samples of occurrence met any of the four individually or cumulatively, is flat-tailed horned lizards were collected significance conditions identified in the significant enough to cause the flat- from the Thousand Palms subarea 1996 DPS policy, and we did not tailed horned lizard to be in danger of (Mulcahy et al. 2006, p. 1826 and Figure identify other considerations that would extinction now or likely to become so 3, p. 1809) (see also Mendelson et al. lead us to conclude that the respective within the foreseeable future throughout 2004, p. 5)]. Although the genetic population segments met the all of its range. We also conclude based affinities of the Dos Palmas occurrence significance element of the policy, on the results of this same analysis are unknown, it is likely this occurrence especially given Congressional guidance presented in Summary of Factors was historically connected with the that the authority to list DPSs be used Affecting the Species that none of these Western Population through a ‘‘sparingly’’ while encouraging the potential habitat threats is significant connection to the north or west (when conservation of genetic diversity. enough to cause the Eastern, Western, or the Salton Basin was dry) or possibly Southeastern distinct population the Eastern Population through a Conservation Status of DPSs segments of flat-tailed horned lizard to connection to the south along the As stated by our DPS policy (61 FR be in danger of extinction now or likely eastern side of the Salton Trough when 4725), if a population segment is to become so within the foreseeable Lake Cahuilla was not full. Thus, the discrete and significant (i.e., it is a future throughout all of their respective evidence suggests that the population of distinct population segment), its ranges. flat-tailed horned lizards in the Dos evaluation for endangered or threatened For Factor B, we concluded that Palmas occurrence within the Coachella status will be based on the Act’s potential threats associated with Valley Population is unlikely to differ definitions of those terms and a review overutilization due to collection for the markedly from the Western Population of the factors enumerated in section pet trade and scientific and educational or Eastern Population in its genetic 4(a). It may be appropriate to assign purposes are not significant threats to characteristics. Therefore, we conclude different classifications to different flat-tailed horned lizards now or within the Coachella Valley Population does DPSs of the same vertebrate taxon. the foreseeable future across its range. not differ markedly from other Above, we determined the Western, We also conclude, based on this same populations of the species in its genetic Eastern, and Southeastern Populations analysis presented in Summary of characteristics. are discrete and significant, and thus, Factors Affecting the Species, that We believe the best scientific and each is a distinct vertebrate population potential overutilization threats are not commercial information available segment. We thus evaluate the significant enough to cause the Eastern, indicates that the Western, Eastern, and conservation status of each of these Western, or Southeastern distinct Southeastern Populations meet the three distinct population segments. We population segments of flat-tailed fourth condition for significance, but do not further separately evaluate the horned lizard to be in danger of that the best scientific and commercial conservation status of the Coachella extinction now or likely to become so information available do not support a Valley Population or the two within the foreseeable future throughout determination that the Coachella Valley occurrences of flat-tailed horned lizards all of their respective ranges. Population (and the Thousand Palms because we determined that these For Factor C, we concluded that and Dos Palmas subareas, individually) population segments do not meet the potential threats associated with disease meet the fourth condition for significance element of the 1996 DPS or predation were not significant threats significance. We did not identify policy, and thus none are considered a to flat-tailed horned lizards now or additional criteria for determining distinct population segment under the within the foreseeable future across its significance beyond the four identified Act and our DPS policy. For the range. We also conclude based on this in the 1996 DPS policy. remainder of the DPS analysis, we same analysis presented in Summary of consider the Coachella Valley Factors Affecting the Species that Conclusion for Significance Element of Population, which includes the potential disease or predation threats 1996 DPS Policy Thousand Palms occurrence and the are not significant enough to cause the We conclude that the Western, Dos Palmas occurrence, to be part of the Eastern, Western, or Southeastern Eastern, and Southeastern Populations Western DPS. Although it is possible distinct population segments of flat- of flat-tailed horned lizards meet the that the Dos Palmas occurrence may tailed horned lizard to be in danger of significance element of the 1996 DPS more properly be placed in the Eastern extinction now or likely to become so policy, but that the Coachella Valley DPS, for the purposes of our evaluation within the foreseeable future throughout Population does not. Loss of the for endangered or threatened status, we all of their respective ranges. Western, Eastern, or Southeastern are considering it to be within the For Factor D, we concluded that Population would result in a significant Western DPS. existing regulatory mechanisms are not gap in the range of the species (second In our analysis of section 4(a) threats, inadequate and do not threaten the flat- significance condition), and information we evaluated whether potential threats tailed horned lizard throughout all or a

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significant portion of its range either the regulatory mechanisms and In our past assessments of the species, now or within the foreseeable future. conservation efforts differ within and following the lead of the information We also conclude based on this same among DPSs, we found no one threat to then available to us, we concluded or analysis of the best available be unique to any one DPS, nor did we implied that the historical range of the information presented in Summary of find a threat that occurred with flat-tailed horned lizard was mostly Factors Affecting the Species that any markedly greater magnitude in any one without substantial discontinuities and potential threats associated with DPS. We therefore conclude that the that modern discontinuities in the inadequate existing regulatory Western, Eastern, and Southeastern species’ range were the result of mechanisms are not significant enough distinct population segments of flat- manmade changes, primarily habitat to cause the Eastern, Western, or tailed horned lizard also are not likely loss through agricultural development Southeastern distinct population to be in danger of extinction now or and the creation of the Salton Sea (for segments of flat-tailed horned lizard to likely to become so within the example, see the Factor A analyses at 58 be in danger of extinction now or likely foreseeable future throughout all of their FR 62625–62626, 62 FR 37857, and 68 to become so within the foreseeable respective ranges. FR 341; also Rado 1981, pp. 1–21; future throughout all or a significant Significant Portion of the Range Hodges 1997, pp. 1–23). This portion of their respective ranges. characterization of the range of the For Factor E, we identified and Having determined that neither the species suggested to the reader that the evaluated threats from other natural or flat-tailed horned lizard nor the conversion from habitat to non-habitat manmade factors including barriers and identified distinct population segments of the large swath of land between the small populations, edge effects, of flat-tailed horned lizard meet the Coachella Valley, Western, Eastern, and pesticide spraying, vehicle activity, definition of an endangered or Southeastern Populations is what drought, and climate change. This threatened species, we must next created those now-separate populations analysis led us to conclude that none of consider whether there are any and that prior to the manmade changes these potential threats, either significant portions of the range where all of the now-lost interstitial areas used individually or cumulatively, is the flat-tailed horned lizard is in danger to be occupied flat-tailed horned lizard significant enough to cause the flat- of extinction or is likely to become habitat. However, the best currently tailed horned lizard to be in danger of endangered in the foreseeable future. available information indicates that extinction now or likely to become so We considered whether any portion of such a conclusion is incorrect. within the foreseeable future throughout the flat-tailed horned lizard’s range all of its range. We also conclude, based warrants further consideration. Our In our 2006 analyses (71 FR 36750– on this same analysis of the best consideration of areas that may 36751), we determined that the area of available information presented in constitute significant portions of the the historical lakebed of the former Lake Summary of Factors Affecting the species’ range focuses on areas where Cahuilla (see Background section), Species, that none of these potential the geographic concentration of threats which occupied most of the areas now threats is significant enough to cause the may be greater relative to the entire under agriculture in the southern half, Eastern, Western, or Southeastern range. We consider whether there are or so, of the Coachella Valley and most distinct population segments of flat- any significant portions of the range of of the area now under agriculture in the tailed horned lizard to be in danger of the flat-tailed horned lizard (the species Imperial Valley (for example, see Patten extinction now or likely to become so as a whole) or of the identified DPSs et al. 2003, p. 3), was frequently within the foreseeable future throughout that are in danger of extinction or are unavailable (through historical and pre- all of their respective ranges. likely to become endangered in the historical time) and likely contained foreseeable future. little quality habitat for the flat-tailed Conclusion for Conservation Status Decisions by Ninth Circuit Court of horned lizard. The 2006 analysis then Element of 1996 DPS Policy Appeals in Defenders of Wildlife v. addressed the now-developed areas In our analysis of the species as a Norton, 258 F.3d 1136 (2001) and outside of the historical lakebed, whole as detailed in Summary of Tucson Herpetological Society v. including remaining portions of the Factors Affecting the Species section, Salazar, 566 F.3d 870 (2009) found that Coachella Valley and Mexicali Valley, we noted potential threats from the Act requires the Service, in and the San Luis Valley. However, as development, invasive species, military determining whether a species is detailed in the Background and further training, vehicle (including OHV) endangered or threatened throughout a discussed in the ‘‘Barriers and Small activity, barriers and small populations, significant portion of its range, to Populations’’ section of Factor E, above, edge effects, pesticide spraying, and consider whether lost historical range of the available information now leads us climate change. Additionally, we a species (as opposed to its current to conclude that the Western, Eastern, identified regulatory mechanisms and range) constitutes a significant portion and Southeastern Populations have long conservation efforts that reduced certain of the range of that species. While this been separated from each other by threats in certain areas. We determined is not our interpretation of the statute, natural barriers south of the Lake that none of the potential threats, either we first address the lost historical range Cahuilla lakebed that pre-date any individually or cumulatively, before addressing the current range. manmade changes. Specimen data show significantly affected the species that large amounts of this now-lost area throughout its range. In that analysis, Lost Historical Range was formerly occupied by the species we also addressed (where appropriate) As shown in Figure 1, the current (see, for example, Funk 1981, p. 281.1), separate flat-tailed horned lizard range of the flat-tailed horned lizard but as described in the Setting and populations, including the Western, consists of three, large, separate Habitat section, above, the evidence Eastern, and Southeastern Populations population areas (the Western, Eastern, also shows that, in addition to the that we have determined, per the and Southeastern Populations), plus historical lakebed of the former Lake analyses in this section, are DPSs. two, small, isolated occurrences that, Cahuilla, some unknown amount of the Although all of the identified potential together, compose the Coachella Valley area in the Mexicali Valley and the San threats occur to a greater or lesser degree Population (see the Description of Luis Valley, was also frequently affected in each of the three DPSs, and although Specific ‘‘Populations’’ section, above). by the deltaic meandering and avulsive

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flooding of the Colorado River. These reductions in range are attributable to contraction due to the loss of this hydrologically active areas likely continued habitat loss (see Factor A). habitat. Most of the lost habitat was lost contained little quality habitat for the (Although adequate sample sizes to early in the 20th century and that lost flat-tailed horned lizard and formed determine population trends have been habitat was not significant enough to natural barriers to movement of flat- difficult to obtain in the flat-tailed lead to substantial extirpation of the tailed horned lizards thereby allowing horned lizard, the distribution of the species within intact habitat (which genetic differentiation among the species, and thus its range, is based on would be detectable through a reduction Western, Eastern, and Southeastern where the species was and is detected— of the species’ distribution). The Populations (see the Populations and presence-absence data—which is much historically lost habitat did not provide Genetics section, above). Thus, as we more easily obtained.) Moreover, the any special or unique features or meet found for the Lake Cahuilla lakebed in agricultural and urban development of any life-history needs of the flat-tailed our 2006 analyses (71 FR 36750–36751), the now-lost historical range did not horned lizard that made those areas any we have also determined that these create any new barriers that separated more significant than any other habitat. additional areas should not be the Western, Eastern, and Southeastern The habitat within the lost historical considered part of the species’ historical Populations (DPSs) but merely range was not continuous and contained habitat. expanded upon pre-existing, natural natural barriers that separated the Therefore, we consider the flat-tailed barriers (see Background section). Western, Eastern, and Southeastern horned lizard’s historical habitat to be Therefore, the historical loss of habitat Populations, which means the historical (1) habitat outside the area of the former has not resulted in substantial present- loss of habitat did not create any new Lake Cahuilla and (2) the habitat outside day ramifications to the species; in other barriers within the lost historical range. the areas historically subject to periodic words, the lost historical range is not We do not expect the agricultural flooding by the Colorado River. Because biologically significant to the flat-tailed development that created the large we do not know the real extent of the horned lizard and does not contribute ‘‘swath’’ of lost habitat to continue to non-habitat areas that created the meaningfully to the viability of the expand substantially, nor do we expect natural barriers separating the species overall or to the viability of each significant amounts of land that are populations, we cannot reasonably DPS. currently under agriculture to become estimate (quantify) the size of the areas Moreover, as described under Factor flat-tailed horned lizard habitat within that do constitute the lost historical A, we do not expect additional the foreseeable future. Therefore, the habitat for each of the separate significant conversion of flat-tailed lost historical range is not a significant populations. As a result, the remainder horned lizard habitat to agriculture in portion of the range for the flat-tailed of this analysis qualitatively considers the future in the Imperial Valley and horned lizard. the species’ lost historical habitat. elsewhere along the Colorado River Because the habitat needs of the flat- given: (1) The existing limitations on the Current Range tailed horned lizard are met within the availability of water for irrigation, and We use the concepts of resiliency, home range of each flat-tailed horned (2) the water transfer agreement with redundancy, and representation (see lizard individual, the areas of former San Diego that requires some fields to below) as the basic tenets for habitat within the lost historical range remain fallow (unirrigated); therefore, determining whether a portion of a did not provide any special or unique agricultural use has even decreased in species’ range is significant to that features or meet any life-history needs this area (IID 2006). species. A portion of a taxonomic that present-day flat-tailed horned The past agricultural and urban species’ or DPS’s range is significant if lizards need to survive. In other words, development that created the swath of it is part of the current range of the there is no evidence in the available now-lost historical habitat in the United species or DPS and it contributes information to indicate that the habitat States and Mexico removed the substantially to the representation, within the lost historical range provided biological features that provided habitat resiliency, or redundancy of the species special features for the flat-tailed horned for the flat-tailed horned lizard in these or DPS. The contribution must be at a lizard such as key breeding grounds, lek areas. Much of this habitat has been level such that its loss would result in sites, or migratory pathways, which are permanently lost due to urbanization, a significant decrease in the viability of examples of special habitat features flooding of the Salton Sea, or both. the species or DPS. other species need to survive. Had the Although habitat lost due to agricultural We chose to identify any portions of habitat within the lost historical range uses could potentially be restored in the range of the species that warrant provided any special or unique features certain cases in the future, most further consideration as the first step in or met any particular life-history needs agricultural fields are isolated from determining whether a taxonomic of the flat-tailed horned lizard—in other existing flat-tailed horned lizard species or DPS is endangered or words, had the habitat in the lost populations by major irrigation canals, threatened in a significant portion of its historical range been significant to the such as the Coachella Canal, Highline range. The range of a species or DPS can species—the loss of these habitat areas Canal, and All-American Canal, as well theoretically be divided into portions in would have been detectable in further as, depending on the site’s location, one an infinite number of ways. However, contraction in the range of the species or more smaller canals and drains. there is no purpose to analyzing or each DPS over the past 100 or so Therefore, we do not anticipate any portions of the range that are not years (more than 25 flat-tailed horned significant amount of previously lost reasonably likely to be significant and lizard generations, as described in our habitat will likely become suitable as endangered or threatened. To identify 2006 analysis (71 FR 36751)), the time habitat for the flat-tailed horned lizard only those portions that warrant further since most of the historical habitat was in the foreseeable future. consideration, we should, under the lost. Since the areas of historical habitat In sum, we believe the lost historical framework we chose for this evaluation, were converted to agriculture early in habitat does not represent a significant determine whether there is substantial the 20th century, the distribution of the portion of the range of the flat-tailed information indicating that (i) the flat-tailed horned lizard has remained horned lizard because the habitat was portions may be significant and (ii) the about the same, except in areas of lost decades ago and the species has not species or DPS may be in danger of continuing urban expansion where such experienced a continuing range extinction there or likely to become so

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within the foreseeable future. In history functions, such as breeding, Western, Eastern, or Southeastern DPSs practice, we believe a key part of this feeding, migration, dispersal, or (each as a whole) are ‘‘significant.’’ analysis is whether the threats are wintering. We found that the Coachella Valley geographically concentrated in some Redundancy of populations may be Population was faced with substantial way. If the threats to the species are needed to provide a margin of safety for threats. Also, we noted certain barrier- essentially uniform throughout its the species or DPS to withstand created ‘‘parts’’ within the ranges of the range, no portion is likely to warrant catastrophic events. This does not mean Western, Eastern, and Southeastern further consideration. Moreover, if any that any portion that provides Populations were small enough that the concentration of threats applies only to redundancy is a significant portion of flat-tailed horned lizards therein were portions of the range that are not the range of a species. The idea is to more likely to suffer from threats significant to the viability of the species, conserve enough areas of the range such associated with small populations (see such portions will not warrant further that random perturbations in the system ‘‘Barriers and Small Populations’’ under consideration. act on only a few populations. Factor E) or were facing or likely to face Under this framework, if we identify Therefore, each area must be examined other threats. any portions that warrant further based on whether that area provides an An important consideration in consideration, we then determine increment of redundancy that is determining what portions of the whether in fact the species or DPS is important to the viability of the species. species’ or distinct population segments’ ranges may be appropriate to endangered or threatened in any Adequate representation insures that consider for this analysis is the fact that significant portion of its range. the species’ adaptive capabilities are there are no specific life-history traits of Depending on the biology of the species, conserved. Specifically, the portion the flat-tailed horned lizard that make the range of the species or DPS, and the should be evaluated to see how it any one portion of its range significantly threats the species or DPS faces, it may contributes to the genetic diversity of more important to the survival of the be more efficient for us to address the the species or DPS. The loss of species than any other. The flat-tailed significance question first, or the status genetically based diversity may horned lizard is a small animal with question first. Thus, if we determine substantially reduce the ability of the that a portion of the range is not limited abilities to move long distances, species or DPS to respond and adapt to significant, we need not determine and the habitat features necessary for future environmental changes. A whether the species is endangered or activities like breeding, feeding, and peripheral population may contribute threatened there; if we determine that sheltering, may be found within or very meaningfully to representation if there the species or DPS is not endangered or close to the home range of each is evidence that it provides genetic threatened in a portion of its range, we individual flat-tailed horned lizard. diversity due to its location on the need not determine if that portion is Moreover, a flat-tailed horned lizard’s margin of the species’ habitat significant. home range size (perhaps as much as 10 The terms resiliency, redundancy, and requirements. ha (25 ac)), although large compared to representation are intended to be Applying the process described above other horned lizard species, is very indicators of the conservation value of for determining whether the flat-tailed small compared to the overall range of portions of the range. Resiliency of a horned lizard or any of the identified the species (1.6 million ha (3.9 million species allows the species to recover DPSs are likely to become endangered ac)). In other words, this species does from periodic or occasional disturbance. throughout a significant portion of their not need any particular portion of its A species or its members within a DPS respective ranges, under this framework range outside the general home-range will likely be more resilient if large we next address whether any portions of area of each individual to meet any life populations exist in high-quality habitat the range of the flat-tailed horned lizard history needs, such as particular that is distributed throughout the range or the identified DPSs warrant further breeding grounds, lek sites, or migratory of the species or DPS in such a way as consideration. Based on past approaches pathways. As such, the ‘‘parts’’ to capture the environmental variability and other treatments in the literature, identified in Factor E are appropriate found within the range of the species or the flat-tailed horned lizard may be subjects to address as potential DPS. It is likely that the larger the size divided into four ‘‘populations.’’ As significant portions of the species’ of a population, the more it will detailed above, we conducted our range. contribute to the viability of the species analysis of threats to the species based, Thus, because the portions of the overall. Thus, a portion of the range of in part, upon those populations. species’ range that compose the a species may make a meaningful Moreover, we determined that the Coachella Valley Population and the contribution to the resiliency of the Western Population (including the portions of the species’ range that are species or DPS if the area is relatively Coachella Valley Population), the formed by the small ‘‘parts’’ of the other large and contains particularly high- Eastern Population, and the three populations may face substantial quality habitat or if its location or Southeastern Population were DPSs threats, we next determine whether characteristics make it less susceptible under the Act per our DPS policy. We these portions of the species’ range are to certain threats than other portions of found that the species as a whole is not ‘‘significant.’’ As described above, we the range. When evaluating whether or in danger of extinction or likely to need not assess whether the portions of how a portion of the range contributes become endangered within the the species’ range that are not facing to resiliency of the species, it may help foreseeable future throughout all of its substantial threats are ‘‘significant.’’ to evaluate the historical value of the range. We also found that the three portion and how frequently the portion DPSs are not in danger of extinction or Coachella Valley Population Area is used by the species or DPS. In likely to become endangered within the As discussed previously, the addition, the portion may contribute to foreseeable future throughout all of their Coachella Valley Population, which is resiliency for other reasons—for respective ranges. Because we peripheral to the population-as-a-whole instance, it may contain an important determined that the DPSs (each as a of the species, now consists of two small concentration of certain types of habitat whole) are not endangered or threatened occurrences, Thousand Palms and Dos that are necessary for members of a within those portions of the species’ Palmas. These two occurrences are species or DPS to carry out their life- range, we need not determine if the small in area and, thus, likely have

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small populations of flat-tailed horned flowing of Lake Cahuilla through entire species, the Western DPS, or the lizards (see ‘‘Barriers and Small historical time has meant these two Eastern DPS. Populations’’). As such, the populations occurrences have likely been Representation—Representation, as of flat-tailed horned lizards that periodically disconnected from each described in greater detail above, comprise these occurrences may not be other and from the Western DPS (or, for ensures that the species’ adaptive large enough to avoid deleterious effects Dos Palmas, possibly the Eastern DPS). capabilities are maintained. The genetic associated with small population size Even prior to any natural or manmade differences between the Thousand (see ‘‘Barriers and Small Populations’’). reductions in the geographical or Palms occurrence and the Western This suggests that the respective numerical extent of these populations, Population are not statistically portions of the flat-tailed horned lizard’s they were outposts of the main significant, despite having some unique range in these two occurrences may face population and did not contribute haplotypes (see Populations and substantive threats and have the meaningfully to the viability of the Genetics in the Background section). potential to be endangered or larger Western Population (or, Thus, the Thousand Palms occurrence does not contribute meaningfully to the threatened; thus, we should evaluate potentially for the Dos Palmas maintenance of the adaptive capabilities whether the portions of the species’ occurrence, the Eastern Population). of the flat-tailed horned lizard range are significant portions of the Thus, the flat-tailed horned lizard species’ range. To do so, we assess (1) rangewide or the Western DPS. populations in the Thousand Palms and Whether the population of flat-tailed Although the genetic affinities of the Dos Palmas occurrences (each horned lizards in each occurrence Dos Palmas occurrence are unknown, it separately or the two combined) do not contributes meaningfully to the is likely this occurrence was historically resiliency, redundancy, and contribute meaningfully to the connected with the Western Population representation of the entire species; (2) resiliency of the entire species, the through a connection to the north or whether the Thousand Palms Western DPS, or the Eastern DPS. west (when the Salton Basin was dry) or occurrence contributes meaningfully to Redundancy—Redundancy, as possibly the Eastern Population through the resiliency, redundancy, and described in greater detail above, a connection to the south along the representation of the Western DPS; and provides a margin of safety for the eastern side of the Salton Trough when (3) whether the Dos Palmas occurrence species or DPS to withstand Lake Cahuilla was not full. Thus, the contributes meaningfully to the catastrophic events. As discussed in the Dos Palmas occurrence likely does not resiliency, redundancy, and ‘‘Barriers and Small Populations’’ contribute meaningfully to the representation of the Western DPS or section under Factor E, the respective maintenance of the adaptive capabilities Eastern DPS. populations of flat-tailed horned lizards of the flat-tailed horned lizard. Resiliency—Resiliency of a species, as in the Thousand Palms and Dos Palmas Therefore, neither the Thousand Palms described in greater detail above, allows occurrences, or the two combined, is occurrence, the Dos Palmas occurrence, the species to recover from periodic or more likely to be significantly affected nor the two occurrences combined (that occasional disturbance. The size of the by deleterious effects associated with is, the Coachella Valley Population) flat-tailed horned lizard population at small population size, including contributes meaningfully to the the Thousand Palms and Dos Palmas catastrophic events, than areas with representation of the entire species, the occurrences (each separately or the two larger populations (see the ‘‘Other Small Western DPS, or the Eastern DPS. combined) is likely small because the ‘Parts’ of the Three DPSs’’ section, Therefore, in sum, we do not expect the Coachella Valley Population as a amount of available habitat within each below). As such, the Coachella Valley whole, or the Thousand Palms and Dos of these occurrence areas are small. occurrences do not provide a significant Palmas occurrences separately, to Small populations are less resilient than margin of safety for the species. contribute substantially to the large populations. Additionally, neither Additionally, as discussed under resiliency, redundancy, or occurrence nor the two combined Resiliency, above, the population of flat- contains an important concentration of representation of the species, the tailed horned lizards in each of these certain types of habitat that are Western DPS, or the Eastern DPS. As a occurrences is likely small because the necessary for flat-tailed horned lizards result of this information, we believe amount of available habitat within each to carry out their life-history functions neither the Coachella Valley Population part is small. Similarly, the entire because each flat-tailed horned lizard (the Thousand Palms and Dos Palmas has the habitat types it needs within its population of the flat-tailed horned occurrences combined), nor the home range. Although the sands in the lizard rangewide and the respective Thousand Palms and Dos Palmas Coachella Valley are largely derived populations of flat-tailed horned lizards occurrences separately, constitute a from local sediments (as opposed to within each DPS are each relatively significant portion of the range of the being derived from the Colorado River, large compared to the respective entire species, the Western DPS, or the as are much of the sands within the populations of flat-tailed horned lizards Eastern DPS. range of the species), flat-tailed horned in the Thousand Palms or Dos Palmas Other Small ‘‘Parts’’ of the Three DPSs lizards occur in a number of areas with occurrences, or the two combined, locally derived sediment (see because the amount of available habitat In our analysis in the ‘‘Barriers and Background). throughout the species’ range and Small Populations’’ section, we Additionally, there is nothing in the within each DPS is relatively large identified certain portions, or ‘‘parts,’’ of available information to indicate that compared to the Coachella Valley the Western, Eastern, and Southeastern the location or characteristics of these occurrences. As such, the Coachella Population areas. In the Distinct occurrences (separately or combined) Valley occurrences, or the two Population Segment section, we makes them significantly less combined, provide an unsubstantial determined these three Populations to susceptible to certain threats than other increment of redundancy. Thus, the be DPSs. We now evaluate whether any portions of the species’ range. Moreover, Thousand Palms and Dos Palmas of these parts constitute a significant there is no indication that these occurrences separately, or the two portion of the range of the flat-tailed occurrences have provided value to the combined, do not contribute horned lizard (the species as a whole) or species historically. The ebbing and meaningfully to the redundancy of the the three DPSs. However, there is no

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purpose to analyzing portions of a thus, likely have small populations of provides a margin of safety for the species’ range that are not reasonably flat-tailed horned lizards or, in the case species or DPS to withstand likely to be both significant portions of of parts E–1 and E–4, which are larger catastrophic events. As discussed in the that species’ range and endangered or in area, likely have small populations of ‘‘Barriers and Small Populations’’ threatened. We have chosen in this flat-tailed horned lizards because they section under Factor E, the respective section to first assess whether the flat- primarily contain areas of deep, actively populations of flat-tailed horned lizards tailed horned lizard is reasonably likely shifting sands of the Algodones Dunes in parts W–2, W–4, W–6, W–8, W–10, to be endangered or threatened within that are likely rarely used by flat-tailed E–1, E–2, E–4, E–6, E–7, E–8, SE–2, SE– each part. horned lizards (see ‘‘Barriers and Small 3, SE–4, SE–6, SE–7, SE–10, SE–11, and For the reasons discussed in the Populations’’). As such, the populations SE–12 are more likely to be significantly Summary of Factors Affecting the of flat-tailed horned lizards in these affected by deleterious effects associated Species section (note that the parts may not be large enough to avoid with small population size, including discussions go beyond the simple yes- deleterious effects associated with small catastrophic events, than the respective no results presented in Tables 3 through population size (see ‘‘Barriers and Small populations of flat-tailed horned lizards 5), we believe the populations of flat- Populations’’). This suggests that the in parts W–1, W–3, W–5, W–7, W–9, W– tailed horned lizard in the respective respective portions of the flat-tailed 11, W–12, E–3, E–5, E–9, SE–1, SE–5, following parts (portions of the species’ horned lizard’s range in the latter group SE–8, SE–9, and SE–13. As such, the range) do not face significant threats: of parts may face substantive threats and former group of parts do not provide a W–1, W–3, W–5, W–7, W–9, W–11, W– have the potential to be endangered or significant margin of safety for the 12, E–3, E–5, E–9, SE–1, SE–5, SE–8, threatened; thus, we should evaluate species. Additionally, as discussed SE–9, and SE–13 (Figures 3 through 7). whether the portions of the species’ under Resiliency, above, the population Although the specifics vary to some range are significant portions of the of flat-tailed horned lizards in each of extent from part to part, none of these species’ range. To do so, we assess these respective parts is likely small parts faces or is likely to face in the whether the population of flat-tailed because the amount of available habitat foreseeable future significant threats horned lizards in each part contributes within each part is small, including the associated with: meaningfully to the resiliency, relatively large (in area) parts E–1 and (1) Small population size, because the redundancy, and representation of the E–4 that primarily consist of the deep, parts are large in size (area) or, for parts species as a whole or to each DPS. actively shifting sands of the Algodones W–7, W–9, and W–11, likely have Resiliency—Resiliency of a species, as Dunes that are likely rarely used by flat- higher densities of flat-tailed horned described in greater detail above, allows tailed horned lizards (see discussions in lizards than the most conservative the species to recover from periodic or the ‘‘Barriers and Small Populations’’ estimate (see the Barriers and Small occasional disturbance. The respective section under Factor E). Similarly, the Populations section) and, therefore, populations of flat-tailed horned lizards entire population of flat-tailed horned likely support large populations of flat- in parts W–2, W–4, W–6, W–8, W–10, lizards and the population within each tailed horned lizards; E–1, E–2, E–4, E–6, E–7, E–8, SE–2, SE– DPS are each likely relatively large (2) Significant loss of habitat from 3, SE–4, SE–6, SE–7, SE–10, SE–11, and development, because what impacts compared to the respective populations SE–12 are likely small because the of flat-tailed horned lizards in parts W– may occur are expected to be small amount of available habitat within each relative to the size of the parts because 2, W–4, W–6, W–8, W–10, E–1, E–2, E– part is small, including the relatively 4, E–6, E–7, E–8, SE–2, SE–3, SE–4, SE– they are (i) remote; (ii) are receiving and large (in area) parts E–1 and E–4 that 6, SE–7, SE–10, SE–11, and SE–12 are expected to continue receiving primarily consist of the deep, actively because the amount of available habitat avoidance, minimization, and shifting sands of the Algodones Dunes throughout the species’ range and mitigation measures associated with the that are likely rarely used by flat-tailed within each DPS is relatively large Rangewide Management Strategy horned lizards (see discussions in the compared to the parts under (including those aspects that have been ‘‘Barriers and Small Populations’’ consideration here (see Tables 3 through incorporated into agency plans that section under Factor E). Small 5). As such, parts W–2, W–4, W–6, W– implement regulatory mechanisms) in populations are less resilient than large 8, W–10, E–1, E–2, E–4, E–6, E–7, E–8, the United States, or in Mexico, populations. Additionally, no one part SE–2, SE–3, SE–4, SE–6, SE–7, SE–10, protections from biosphere reserves and contains an important concentration of listing under the Official Mexican certain types of habitat that are SE–11, and SE–12 provide an Norm; or (iii) some combination thereof; necessary for flat-tailed horned lizards unsubstantial increment of redundancy. and to carry out their life-history functions Thus, none of the flat-tailed horned (3) Climate change; nonnative, because each flat-tailed horned lizard lizard populations in the remaining invasive species; or other range-wide has the habitat types it needs within its parts provide a significant level of threats identified in the five-factor home range. Moreover, there is nothing redundancy for the species as a whole analysis, because none of these potential in the available information to indicate or to each DPS. threats are significantly concentrated in that the location or characteristics of Representation—Representation, as any one part. part W–2, W–4, W–6, W–8, W–10, E–1, described in greater detail above, As a result, the flat-tailed horned E–2, E–4, E–6, E–7, E–8, SE–2, SE–3, ensures that the species’ adaptive lizard is not reasonably likely to be SE–4, SE–6, SE–7, SE–10, SE–11, or SE– capabilities are maintained. The endangered or threatened within the 12 makes it significantly less susceptible scientific information on the genetics of parts listed above. Thus, these parts do to certain threats than other portions of flat-tailed horned lizard populations not warrant further consideration in this the species’ range. Thus, none of the indicates that the Western, Eastern, and section. flat-tailed horned lizard populations in Southeastern Populations (DPSs) are The remaining parts, W–2, W–4, W– the remaining parts contribute significantly different from each other 6, W–8, W–10, E–1, E–2, E–4, E–6, E– meaningfully to the resiliency of the (see Populations and Genetics); thus, 7, E–8, SE–2, SE–3, SE–4, SE–6, SE–7, species as a whole or to each DPS. the representation of the species is SE–10, SE–11, and SE–12 (Figures 3 Redundancy—Redundancy, as provided by the three Populations. through 7), are either small in area and, described in greater detail above, Although we do not have genetic data

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from every ‘‘part,’’ the available likely contained small populations of reasonably likely to be endangered or information suggests the genetic flat-tailed horned lizards that did not threatened; thus, we did not need to diversity is fairly uniform and does not contribute meaningfully to the species’ determine whether the portions of the differ significantly within each of the resiliency, redundancy, or range that these parts represented are three DPSs. As such, no one part within representation of the species as a whole significant portions. We determined that the respective DPSs contributes or of each DPS. We determined, the flat-tailed horned lizards in parts meaningfully to the representation of therefore, the portions of the flat-tailed W–2, W–4, W–6, W–8, W–10, E–1, E–2, the species as a whole or to each DPS. horned lizard’s range in parts W–2, W– E–4, E–6, E–7, E–8, SE–2, SE–3, SE–4, Moreover, as discussed in the 4, W–6, W–8, W–10, E–1, E–2, E–4, E– SE–6, SE–7, SE–10, SE–11, and SE–12 Populations and Genetics section, one 6, E–7, E–8, SE–2, SE–3, SE–4, SE–6, may face substantive threats and have part, Part SE–2, shows evidence SE–7, SE–10, SE–11, and SE–12 are not the potential to be endangered or suggesting the genetic variability of the significant portions of the range of the threatened, meaning that we needed, flat-tailed horned lizard population in species as a whole or of each DPS. under our framework, to assess whether that part has declined as a consequence Summary of Significant Portion of the the flat-tailed horned lizards in these of being small and isolated by a Range parts constituted significant portions of manmade barrier. This suggests that the the species’ range. We found that the In summary, we examined whether species’ adaptive capabilities in this portions of the species’ range within the the lost historical range of the species, part have declined. That is, the ability respective parts in this latter group the current range of the species in the of the flat-tailed horned lizard likely contained small populations of population to provide adequate Coachella Valley Population, or the current range of the species in the other flat-tailed horned lizards that did not representation has been reduced in Part contribute meaningfully to the SE–2. It is possible the representation of respective ‘‘parts’’ of the Western, Eastern, and Southeastern DPSs resiliency, redundancy, or the other parts with small populations representation of the species as a whole and with complete barriers has been or constituted significant portions of the species’ or distinct population or of each DPS. Thus, we determined may become similarly reduced. the portions of the range of this latter Therefore, it is unlikely that parts W–2, segments’ respective ranges under the Act. We determined the lost historical group of parts are not significant W–4, W–6, W–8, W–10, E–1, E–2, E–4, portions of the range of the species as E–6, E–7, E–8, SE–2, SE–3, SE–4, SE–6, habitat does not represent a significant portion of the range of the flat-tailed a whole or of each DPS. Therefore, no SE–7, SE–10, SE–11, and SE–12 horned lizard because the habitat was portion of the range of the flat-tailed contribute significantly to the species’ lost decades ago and, despite the horned lizard is a ‘‘significant portion of adaptive capabilities, and thus, the amount of time that has since [the species’] range’’ under the Act. respective parts do not contribute transpired, the species has not meaningfully to the representation of Conclusion experienced a continuing range the species as a whole or to each DPS. contraction due to the past loss of Threats to the flat-tailed horned lizard In sum, we found that none of the habitat. Additionally, the historically rangewide or within the three identified ‘‘parts’’ identified in the ‘‘Barriers and lost habitat did not provide any special DPSs have been reduced, managed, or ’’ Small Populations section constituted or unique features or meet any life- eliminated, or found to be less significant portions of the range of the history needs of the flat-tailed horned substantial than originally thought. flat-tailed horned lizard. For the reasons lizards that made those areas any more Additionally, implementation of the discussed in the Summary of Factors significant than any other habitat. Interagency Conservation Agreement Affecting the Species section (note that Moreover, the lost historical range was and associated Rangewide Management the discussions go beyond the simple not continuous and contained natural Strategy, including those aspects of it yes-no results presented in Tables 3 barriers that separated the Western, that have been incorporated into through 5), we determined that the Eastern, and Southeastern Populations. documents that implement existing portions of range of the flat-tailed We also determined that neither the regulatory mechanisms, is an important horned lizard in parts W–1, W–3, W–5, Coachella Valley Population as a whole conservation effort that reduces threats W–7, W–9, W–11, W–12, E–3, E–5, E– nor the Thousand Palms and Dos in the United States and benefits the 9, SE–1, SE–5, SE–8, SE–9, and SE–13 Palmas occurrences separately species throughout its range and within are not reasonably likely to be contribute substantially to the the identified DPSs. Therefore, we endangered or threatened; thus, we did resiliency, redundancy, or conclude that none of the existing or not need to determine whether the representation of the entire species, the potential threats are likely to cause the portions of the range that these parts Western DPS, or the Eastern DPS. flat-tailed horned lizard as an entire represented are significant portions. We Therefore, we conclude that neither the species or as any one of the Western, determined that the flat-tailed horned Coachella Valley Population as a whole Eastern, or Southeastern DPSs to be in lizards in the remaining parts, parts W– nor the Thousand Palms and Dos danger of extinction or likely to become 2, W–4, W–6, W–8, W–10, E–1, E–2, E– Palmas occurrences separately so within the foreseeable future 4, E–6, E–7, E–8, SE–2, SE–3, SE–4, SE– constitute a significant portion of the throughout all or a significant portion of 6, SE–7, SE–10, SE–11, and SE–12, may range of the entire species, the Western its range. face substantive threats and have the DPS, or the Eastern DPS. potential to be endangered or Lastly, we determined that none of Withdrawal of Proposal To List Flat- threatened. As such, we assessed the ‘‘parts’’ identified in the ‘‘Barriers Tailed Horned Lizard whether any of the portions of the and Small Populations’’ section species’ range within the parts in this represented a significant portion of the Based on the information discussed latter group is a significant portion of range of the flat-tailed horned lizard. We above, we withdraw our November 29, the species’ range overall or of the found that the flat-tailed horned lizards 1993 (58 FR 62624), proposal to list the ranges of each DPS. We found that the in Parts W–1, W–3, W–5, W–7, W–9, W– flat-tailed horned lizard (Phrynosoma portions of the species’ range within the 11, W–12, E–3, E–5, E–9, SE–1, SE–5, mcallii) as a threatened species under respective parts in this latter group SE–8, SE–9, and SE–13 were not the Act.

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Peer Review perform military readiness activities at horned lizard Interagency Conservation As described in our 2003 withdrawal NAF El Centro; (2) the species is not Agreement is a viable mechanism for (68 FR 340) and in accordance with our threatened throughout a significant the long-term conservation of the July 1, 1994, Interagency Cooperative portion of its range; (3) conservation species in the absence of listing under Policy for Peer Review in Endangered should be implemented through the the Act. Species Act Activities (59 FR 34270), we existing Interagency Conservation Our Response: We agree the solicited six individuals with scientific Agreement, the Rangewide Management Interagency Conservation Agreement expertise on flat-tailed horned lizard, its Strategy, and the updated NAF El and associated Rangewide Management habitat, and the geographic region in Centro INRMP; and (4) conservation Strategy is a viable conservation effort to which the species occurs to provide should be implemented through a promote the long-term conservation of their expert opinion and to review and continued working partnership with flat-tailed horned lizard. The avoidance, interpret available information on the other State and Federal agencies, minimization, and mitigation measures species’ status and threats. Peer including the U.S. Navy. incorporated into the Yuma Area reviewer comments and our responses Our Response: Based on the rationales Service Highway project reduced to those comments were included in our provided in this document, we agree impacts to the flat-tailed horned lizard 2003 withdrawal (68 FR 340) and are with the U.S. Navy that the species does and is an example of how the hereby included in this document by not warrant listing under the Act. Rangewide Management Strategy can reference. Additionally, we agree that the reduce impacts to the species associated Interagency Conservation Agreement with development (see Factor A). Summary of Comments and and associated Rangewide Management Comment 3: The CDPR expressed a Recommendations Strategy make important contributions concern that listing flat-tailed horned lizard as a threatened species would Public Comments to reducing threats to the flat-tailed horned lizard and its habitat through restrict CDPR’s ability to manage All public and peer review comments efforts contributed by the Service, BLM, recreational activities and park we received during public comment BOR, U.S. Marine Corps, U.S. Navy, operations at Ocotillo Wells State periods and public hearings prior to our Arizona Game and Fish Department, Vehicular Recreation Area (SVRA), and March 2, 2010, Federal Register CDFG, and CDPR. Although many of that listing the species under the Act announcement on the reinstatement of these efforts are voluntary, conservation may cause OHV use to move to off-site the 1993 proposed rule and notice of actions are formally incorporated into areas with little or no management public hearings are included in this planning documents of participating control. The CDPR also stated that document by reference (see Previous agencies (such as the NAF El Centro listing the species may potentially Federal Action section for dates, times, INRMP and BLM’s California Desert reduce the number of visitors, resulting and locations of prior comment periods Conservation Area Plan). We appreciate in a negative economic impact on the and hearings). the U.S. Navy’s support of this long- region. Further, they believe that Since the proposed rule was term partnership and commitment to recreational OHV use does not reinstated on March 2, 2010 (75 FR conservation of sensitive species, conclusively show adverse effects to the 9377), there has been one public including the flat-tailed horned lizard, species. comment period and four public and their habitats through its Our Response: Although OHV activity hearings. During the 60-day comment participation in the Interagency has the potential to crush flat-tailed period from March 2 to May 3, 2010, for Conservation Agreement and horned lizards (see Factor E) and impact the reinstated proposed rule, we implementation of the NAF El Centro the species’ habitat (Factor A), we received a total of 24 comment letters in INRMP. For additional information on determined it is not currently a response to our request for new the Interagency Conservation Agreement substantial threat to the species information: 2 from Federal agencies and the associated Rangewide throughout its range. We agree that OHV (duplicate letter from 2 submitters), 4 Management Strategy and the U.S. activity in designated and managed from State or local agencies and Navy’s conservation actions, please see open or limited-use areas is preferable governments, and 18 from organizations Management and Populations under the to unmanaged OHV activity elsewhere. or individuals. During the public Background section and Sikes Act under We acknowledge CDPR’s contributions hearings on March 23, 2010, in Palm Factor D. to the Rangewide Management Strategy Desert, California, and March 24, 2010, through monitoring and management at Comments From State Agencies in Yuma, Arizona, we received a total of Ocotillo Wells SVRA, and we encourage 4 comments: 1 written comment and 3 Comment 2: The Arizona Department CDPR’s continued participation in the oral comments. Two of these comments of Transportation believes the flat-tailed Interagency Conservation Agreement. were from local government horned lizard Interagency Conservation Comment 4: The CDPR states that representatives and the remaining two Agreement is an adequate regulatory long-term studies of flat-tailed horned from organizations or individuals. All mechanism that provides strong lizard are needed because annual comments received were reviewed for protection for the species on signatory climatic conditions can result in substantive issues and new information lands. Much of the remaining habitat in variability in population sizes. They regarding the 1993 proposed rule to list southwestern Arizona is managed by believe that long-term studies and an the flat-tailed horned lizard as a agencies that are signatories to the adaptive monitoring program are threatened species, and we address Interagency Conservation Agreement. warranted prior to listing the species those comments below. For example, project proponents for the under the Act. construction of Arizona State Route 195 Our Response: We agree that more Comments From Federal Agencies (Yuma Area Service Highway) used the information on the effects of weather Comment 1: The U.S. Navy does not Rangewide Management Strategy to and climate on the flat-tailed horned support the listing of flat-tailed horned avoid and mitigate impacts to the flat- lizard and its habitat would be helpful; lizard as a threatened species because: tailed horned lizard and its habitat. however, we are required to make a (1) Listing or designation of critical Additionally, the Arizona Department of determination based on the best habitat would encroach on the ability to Transportation believes the flat-tailed available scientific and commercial

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information. We determined the flat- during periods of both drought and assessment of the five listing factors tailed horned lizard does not require increased rain, they rebound as do described in the Act and the standards protection under the Act. CDPR’s populations of flat-tailed horned lizards for listing as endangered or threatened. contributions to the Rangewide (Tevis 1958, p. 701; Barrows and Allen A determination is made using the best Management Strategy have included 2009, p. 311). Harvester ants are also scientific and commercial information funding studies to increase the capable of surviving extremes in available. In the Summary of Factors knowledge of the species, and we temperature (Tevis 1958, p. 704). The Affecting the Species section, we encourage CDPR’s continued effects that global climate change may address the potential threats that may be participation, including contributing to have on localized climate in areas affecting the species, including those developing and implementing long-term inhabited by flat-tailed horned lizards identified by the commenter. studies and adaptive management and harvester ants is unclear, and we Additionally, we have also addressed programs. are not aware of any evidence indicating the Coachella Valley Population in that harvester ant populations will detail. Comments Related to Biology, Ecology, decline in the foreseeable future. Comment 9: One commenter opposed or Climate Change Comment 7: One commenter stated a to the listing of the flat-tailed horned Comment 5: One commenter believes belief that the Service’s final lizard believes that before this species flat-tailed horned lizard populations determinations in the past have been should be considered for listing, will take longer to ‘‘* * * rebound to correct and the flat-tailed horned lizard researchers should conduct monitoring stable wild populations than other should not be listed as threatened under of the full desert ecosystem, as declines classes of animals.’’ The commenter the Act. The commenter further stated for this species may be a result of believes listing flat-tailed horned lizard that there are more flat-tailed horned natural processes. as a threatened species under the Act is lizards known today compared to 20 Our Response: Our determination of warranted because of low clutch years ago, and (with respect to climate whether to list a species as endangered survival rates from breeding to maturity change) there has been adequate rainfall or threatened is based on our due to impacts from predators and to produce forage in the desert for this assessment of the five listing factors human activities. species to flourish. described in the Act using the best Our Response: The commenter did Our Response: As discussed in the available scientific and commercial not provide any information regarding Background section, the number of flat- information. These include potential the class of animals to which he or she tailed horned lizards is difficult to threats from natural and manmade was referring in comparison to the flat- estimate. We do not have acceptably sources. Although anecdotal evidence tailed horned lizard, or any information accurate data to show any trend, either suggests that flat-tailed horned lizard to substantiate the claim that wild increasing or decreasing, in flat-tailed populations are smaller now than populations of flat-tailed horned lizards horned lizard populations. Rainfall compared to the past (for example, are not stable. With regards to the varies from year to year in the Colorado Luckenbach and Bury 1983, p. 278), we commenter’s concerns about ‘‘low clutch Desert (Shreve and Wiggins 1964, pp. do not have data to suggest a positive or survival rates from breeding to maturity 18–20). We determine if a species needs negative trend (see Population due to impacts from predators and protection under the Act based on Dynamics in the Background section). human activities,’’ flat-tailed horned analysis of the species’ status relative to Comments Related to Threats lizards are known to produce relatively one or more of the five factors described small clutches of eggs (N = 31; mean in section 4(a)(1) of the Act, and the Comment 10: Four commenters clutch size = 4.7; range = 3 to 7) standards for listing as endangered or support listing the flat-tailed horned (Howard 1974, p. 111) compared to threatened (see Summary of Factors lizard as a threatened species, and one most other horned lizards (Sherbrook Affecting the Species section). We commenter supports listing as an 2003, p. 139), and predation has been determined the species is not in need of endangered species with designated identified as a potential threat to the the protections afforded by the Act at critical habitat. These commenters flat-tailed horned lizard (FTHLICC this time. believe listing is warranted due to a 2003a, pp. 16–17). However, available Comment 8: One commenter provided number of threats, including: information indicates predation does information resulting from research they Recreation; OHV use (such as in the not appear to be excessively high conducted on flat-tailed horned lizard Yuha Desert, Coachella Valley, West throughout its range, although it is habitat loss in the Coachella Valley. The and East Mesas, near Algodones Dunes, likely higher than natural levels near commenter believes that the reasons and near Yuma, Arizona); construction developed areas. Such results suggest that the flat-tailed horned lizard was not of the border fence and border patrol that higher levels of predation of flat- listed in the past are because there was traffic; development (including tailed horned lizards observed in some not enough known about this species’ renewable energy projects such as SES areas is an ‘‘edge effect,’’ but much of the biology and distribution, and the largest Solar Two Project or Ocotillo Express species’ distribution is away from share of the species’ distribution was on Wind Project); power lines (Sunrise habitat edges (see Factor C, Disease or Federal (BLM, DOD) lands such that the Powerlink); road/highway development Predation section). species could be managed without (Yuma Area Service Highway, El Golfo Comment 6: One commenter states listing. The commenter’s opinion is that to Rocky Point Highway); other that climate change will become more of neither of the above reasons is miscellaneous development (such as an issue as ant population numbers applicable today. The commenter also Travertine Point, Drop 2 Reservoir, All decline because flat-tailed horned lizard believes the Coachella Valley has been American Canal, Coyote Wells Specific populations will subsequently decline. underrepresented in past assessments Plan Project, Reynolds Atlas RV Storage Our Response: Flat-tailed horned and that construction of the border Facility); nonnative plant invasions; lizards do feed primarily on harvester fence, OHV activity, and development predation; and climate change. In ants; however, what effects climate of energy facilities pose threats to the general, the commenters believe these change may have on harvester ant species. threats will continue, resulting in more populations is unclear. Although Our Response: Our determination of habitat lost than gained. Further, the populations of harvester ants decline whether to list a species is based on our commenter that asserts the species

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should be listed as endangered states largely occurring within areas that were 2001, pp. 1–24; FTHLICC 2003b, pp. 1– that Federal protection is necessary to previously developed for agriculture 32; FTHLICC 2004, pp. 1–33; FTHLICC ensure the survival of the species and and is not resulting in additional habitat 2005, pp. 1–37; FTHLICC 2006, pp. 1– eventual recovery, and ultimately loss because the prior agricultural 34; FTHLICC 2007, pp. 1–33; FTHLICC reduce the costs of recovery. conversion had already made the land 2008a, pp. 1–35; FTHLICC 2009, pp. 1– Our Response: Although we unavailable for the species. Urban 38; FTHLICC 2010, pp. 1–33). Most of acknowledge losses of habitat can and development in flat-tailed horned lizard the benefits to the species occur within do occur through natural and manmade habitat is occurring, but in a limited the United States. Although processes, the determination to list a area compared to the large area implementation of the Rangewide species is made by looking at the five occupied by the species. Additionally, Management Strategy is also factors described in section 4(a)(1) of the large areas of the species’ range are contributing to the conservation of the Act and the status of the species relative under some level of protection where species in Mexico by promoting to the standards for listing as urban development is prevented or partnerships with local organizations in endangered or threatened. This restricted, including Management Areas that country that are implementing determination is made solely on the created through implementation of the programs that benefit the species, the basis of the best scientific and Rangewide Management Strategy, CDPR benefits associated with the avoidance, commercial information available, and lands, BLM wilderness, Coachella minimization, and mitigation measures takes into account regulatory Valley MSHCP reserves, and portions of called for by the Rangewide mechanisms that many benefit the two biosphere reserves in Mexico. Management Strategy are not in effect in species and those efforts, if any, being Moreover, where urban development Mexico. As such, the benefits afforded made by any State or foreign nation, or may occur, its impact is further reduced the species through implementation of any political subdivision of a State or (through avoidance, minimization, and the Rangewide Management Strategy, foreign nation, to protect the species mitigation) by the measures that benefit important though they may be, are through habitat protection or other the flat-tailed horned lizard (such as the limited. We appreciate the commenters’ conservation practices. As described in Rangewide Management Strategy, support of the Interagency Conservation the Summary of Factors Affecting the Coachella Valley MSHCP, and Mexican Agreement that is benefitting the flat- Species section, we assessed the Federal listing). Thus, we concluded tailed horned lizard and its habitat. potential threats to the species using the that urban development is not a Please see our response to Comment 1 five factors. We also assessed the substantial threat to the species. and Management and Populations existing efforts and measures that under the Background section for more Comments Related to the Rangewide benefit the species or its habitat that information regarding the Rangewide Management Strategy may potentially reduce threats. We Management Strategy. determined that threats to the flat-tailed Comment 12: Four commenters state Regarding the commenters’ concern horned lizard throughout its range, that the Rangewide Management over the possibility that we may make including recreational OHV activity; Strategy currently in place is working to a determination to list the species various types of development; invasive, the benefit of the species, and there is without complete flat-tailed horned nonnative plants; predation; and climate no need to list the flat-tailed horned lizard survey information, we note that change, are not of a magnitude that it is lizard as a federally threatened species. we are required to make a final listing likely to become endangered in the Two of these commenters further agree determination. Our determination of foreseeable future. Specifically, the with the 2008 Annual Progress Report whether to list a species as endangered identified development projects are not which states that the Interagency or threatened is based on our a significant threat to the species Conservation Agreement and Rangewide assessment of the five listing factors throughout its range or the respective Management Strategy continue to described in the Act using the best DPSs identified in the Distinct provide an effective management focus scientific and commercial information Population Segment section, above, to conserve flat-tailed horned lizard available. Although we agree population because the projects (1) are subject to habitat throughout its range. Two trend data would help us better the avoidance, minimization, and commenters also expressed concern that understand the current status of the compensation measures of the listing the species could undermine the species, we must meet our obligations Rangewide Management Strategy (in the Interagency Conservation Agreement under the Act by examining the threats United States only); (2) are relatively and questioned the efficacy of listing the to the species. This analysis is presented small compared to the range of the flat-tailed horned lizard prior to in the Summary of Factors Affecting the species or DPSs; (3) do not result in completion of the surveys called for by Species section. We conclude that the complete barriers to flat-tailed horned the Rangewide Management Strategy. species is not in need of the protections lizard movement; (4) do not result in the Our Response: We agree with the afforded by the Act at this time. elimination of large ‘‘parts’’ where the commenters that the Rangewide Additionally, because we are not listing deleterious effects associated with small Management Strategy is providing the species, the question of the potential population size are likely to important conservation benefits to the effects of listing on the implementation substantially affect the population; (4) flat-tailed horned lizard and its habitat of the Interagency Conservation or a combination of these, as detailed in in the United States. Although many of Agreement is moot. the Summary of Factors Affecting the these efforts are voluntary, conservation Comment 13: Three commenters Species section. actions are formally incorporated into asserted that implementation of the Comment 11: One commenter planning documents of participating Rangewide Management Strategy, believes that urban development is agencies (such as BLM’s California including the designation of conflicting with flat-tailed horned lizard Desert Conservation Area Plan). Management Areas, is not working to survival. Moreover, most of the measures recover the species. The commenters Our Response: As described in the outlined in the Rangewide Management stated that mitigation lands are Urban Development section under Strategy are being successfully insufficient to make up for losses of Factor A, urban development within the implemented (FTHLICC 1998, pp. 1–11; habitat, especially from threats such as range of the flat-tailed horned lizard is FTHLICC 1999, pp. 1–13; FTHLICC OHV use and large-scale renewable

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energy projects. Two of the commenters percent of the habitat in Sonora in topography, destruction of vegetation stated the strategy is inadequate and not (Mexico) lies within two Mexican that is a food source for harvester ants, rangewide. A fourth commenter stated Federal natural protected areas where and increased dust deposition on that the Service has relied heavily on impacts from development and other vegetation. Additionally, the first the Rangewide Management Strategy to activities is limited (see Management commenter believes the Service should prevent the flat-tailed horned lizard’s and Populations in the Background analyze the impacts of the border fence listing in the past. section for further discussion). and proposed solar projects on the Our Response: With regard to the Regarding the use of the Rangewide viability of flat-tailed horned lizard commenters’ concerns that mitigation Management Strategy in our past listing populations and cumulative impacts of lands may be insufficient to recover the determinations (withdrawals), we did habitat loss. species, we concluded that none of the not rely solely on the Rangewide Our Response: As discussed in our existing or potential threats are likely to Management Strategy in our decisions, Factor A and E analyses (Summary of cause the flat-tailed horned lizard as an nor do we do so in this determination. Factors Affecting the Species section), entire species or as any one of the As we state in our response to Comment we acknowledge that the border fence Western, Eastern, or Southeastern DPSs 12, the evidence indicates that and solar (energy generation) projects to be in danger of extinction or likely to implementation of the Rangewide may result in the loss or degradation of become so within the foreseeable future Management Strategy is providing flat-tailed horned lizard habitat and throughout all or a significant portion of important conservation benefits to the potentially serve as barriers, isolating its range; thus, the species does not flat-tailed horned lizard and its habitat; populations of flat-tailed horned lizards. need to be ‘‘recovered.’’ Implementation however, that is but one aspect we Although not extensively discussed by of the Rangewide Management Strategy, consider. Our determination to list a the Rangewide Management Strategy, including the mitigation (compensation) species is made by looking at the five private development of solar and other by the signatory agencies is providing factors described in section 4(a)(1) of the energy generation facilities on lands for the consolidation of the existing Act and the status of the species relative controlled by signatory agencies is still Management Areas by purchasing the standards for listing as endangered subject to the avoidance, minimization, private inholdings within the or threatened. This determination is and mitigation measures called for by Management Areas. Moreover, made solely on the basis of the best the Rangewide Management Strategy. implementation of the avoidance and scientific and commercial information For example, the project proponent for minimization measures included in the available, and takes into account those the Imperial Valley Solar Project Rangewide Management Strategy is efforts, if any, being made by any State designed the project to avoid and reducing certain potential future threats, or foreign nation, or any political minimize impacts to flat-tailed horned including development of energy subdivision of a State or foreign nation, lizard Management Areas and is generation facilities and associated to protect the species through habitat providing funds to acquire off-site infrastructure on signatory lands. protection or other conservation habitat areas as compensation for With regard to the commenters’ practices. Our assessment of the effects unavoidable impacts, all per the concerns that the Rangewide of the five listing factors on the flat- specifications of the Rangewide Management Strategy is not rangewide, tailed horned lizard is presented in the Management Strategy (BLM 2009, pp. 4– the purpose of this strategy is to provide Summary of Factors Affecting the 7 to 4–10). Because of the prevalence of a framework for conserving sufficient Species section. Our assessment of those Federal and State lands in the U.S. habitat to maintain several viable efforts being made to protect the species portion of the range of the flat-tailed populations of the flat-tailed horned through habitat protection or other horned lizard and because most of this lizard throughout the range of the conservation practices is presented in land is managed by signatories to the species in the United States. Five the Conservation Efforts section (see Interagency Conservation Agreement Management Areas were designed to also Management and Populations implementing the Rangewide identify large areas of public land in the under the Background section)—which, Management Strategy, we expect that United States where flat-tailed horned in this case, included the Rangewide the vast majority of proposed energy lizards have been found, and to include Management Strategy. Thus, we have development projects that are likely to most flat-tailed horned lizard habitat considered but have not relied solely affect flat-tailed horned lizard habitat identified as key areas in previous upon the Rangewide Management will be subject to the avoidance, studies (Turner et al. 1980, pp. 1–47; Strategy in our determination. minimization, and compensation Turner and Medica 1982, pp. 815–823; Comment 14: One commenter states measures incorporated into the Rorabaugh et al. 1987, pp. 103–109; that the Rangewide Management Rangewide Management Strategy (see FTHLICC 1997, p. 35). Furthermore, the Strategy does not discuss impacts of the Energy Generation and Facility Management Areas were delineated to border fence (which they believe Development section). include areas as large as possible, while isolates populations) and proposed solar Such projects may also serve as avoiding extensive, existing and energy projects. Specifically, this barriers to flat-tailed horned lizard predicted management conflicts (such commenter and a second commenter movement. Many of the proposed and as OHV open areas). The Management believe that the border fence in the anticipated projects are likely to occur Areas are meant to be the core areas for Yuha Management Area and the in the Western Population area. As maintaining self-sustaining populations proposed Tessera Solar North America described in the ‘‘Barriers and Small of flat-tailed horned lizards in the Project (also known as the Imperial Populations’’ section under Factor E, the United States (FTHLICC 2003a, p. 47). Valley Solar Project) will result in parts of the Western Population north Although this strategy does not include isolated populations of the species and and south are large enough to likely not Mexico, implementation of the fragmented habitat. Further, the second be substantially affected by the threats Rangewide Management Strategy commenter believes this project will associated with small population size. includes coordination with partners in result in impacts to the flat-tailed Moreover, Interstate 8, which runs along Mexico to promote efforts to benefit the horned lizard and its habitat from the southern edge of the Imperial Valley species in that country (FTHLICC 2009, construction and maintenance, Solar Project and many of the other p. 14). Additionally, approximately 60 vibrations from vehicle traffic, changes proposed or anticipated energy

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generating projects in the area, is allowing some connectivity between the should be implemented to eradicate already likely to be a substantial barrier Yuha Desert Management Area and the Argentine ants (Linepithema humile), to flat-tailed horned lizards within the areas of habitat in Mexico. which displace the main food source area of the Imperial Valley Solar project. Comment 15: One commenter (harvester ants) for flat-tailed horned Development of renewable energy is believes the Rangewide Management lizards. not without impacts, but Strategy does not provide enough Our Response: We agree with the implementation of the Rangewide protection because the document commenter that there is sufficient Management Strategy, either under the acknowledges that it is unknown management and conservation occurring voluntary Interagency Conservation whether the lands set aside are for flat-tailed horned lizards (see the Agreement or as it is incorporated into sufficient, and that the Ocotillo Wells Finding section and Management and existing regulatory mechanisms, is State Vehicular Recreation Area is not Populations under the Background anticipated to reduce the direct and being managed adequately. A second section of this document for discussion indirect effects, including habitat loss commenter stated that they believe BLM of the long-term management of this and isolation of populations. We do not is understaffed and underfunded, which species). We will continue to work with believe vibrations of vehicle traffic, has led to its inability to reduce impacts our partners to implement management changes in topography, destruction of on flat-tailed horned lizard Management actions to benefit this species. vegetation that is a food source for Areas. With regard to the commenter’s harvester ants, and dust on vegetation Our Response: As described in the concern about Argentine ants, the will be any more substantial than the ‘‘Barriers and Small Populations’’ evidence indicates that Argentine ants actual loss or degradation of flat-tailed section under Factor E, we evaluated the are not a threat to flat-tailed horned horned lizard habitat, the effects of size of the parts formed as a result of lizards. Argentine ants do not tolerate which we anticipate to be reduced by potential barriers. We calculated the hot, dry conditions (Holway et al. 2002, avoidance, minimization, and Western, Eastern, and Southeastern p. 1610). The range of the flat-tailed mitigation measures of the Rangewide Population areas, as defined herein and horned lizard is hot and dry (see Management Strategy. Moreover, the based upon the current distribution map Background section), suggesting that cumulative effects of habitat loss are presented in the revised Rangewide Argentine ants do not invade flat-tailed reduced through implementation of the Management Strategy (FTHLICC 2003a, horned lizard habitat to any substantial Rangewide Management Strategy by the p. 5), are 341,989 ha (845,073 ac), degree (Barrows et al. 2006, p. 492); creation and maintenance of large 169,617 ha (419,133 ac), and 1,073,551 thus, they do not substantially affect the blocks of flat-tailed horned lizard ha (2,652,802 ac), respectively. Within primary food of the species throughout habitat, including the establishment of those three Population areas combined, most of the species’ range. Therefore, we Management Areas, the 1 percent cap on we found about 91 percent of the area, do not believe eradication of Argentine impacts, the avoidance and despite containing potential barriers, is ants in flat-tailed horned lizard habitat minimization measures directed by the in large enough blocks that the is a warranted management action to Rangewide Management Strategy, and populations of flat-tailed horned lizards benefit the species. the consolidation of the respective are not likely to be affected by threats Comment 17: One commenter states Management Area through the purchase associated with small populations. that the management strategy is of private inholdings with monies Although the Rangewide Management sufficient for flat-tailed horned lizard acquired from compensation for Strategy is an important conservation and therefore listing this species is not unavoidable impacts from development effort that provides substantial benefit to warranted. Specifically, the commenter activities. the flat-tailed horned lizard and its described the following management Regarding the concerns raised by the habitat, especially within the United actions that are benefiting the species: commenter about the border fence, we States, the status of the species does not (1) Since 1997, the Imperial Irrigation also acknowledge in our Factor E depend solely upon the lands set aside District has paid $10,000 to offset analysis that tactical infrastructure through implementation of the potential project impacts to habitat; (2) (such as fencing, lighting, and access Rangewide Management Strategy. although border patrol and unpermitted and patrol roads) along portions of the Similarly, the status of the flat-tailed OHV use continue to impact the species, border fence area has the potential to horned lizard does not depend solely on there are no significant trends in lizard serve as a barrier for flat-tailed horned management that may or may not be encounter rates in Yuha Desert, East lizard movement. However, installed adequate on Ocotillo Wells SVRA; Mesa, or West Mesa from 1979 to 2001; fencing has been constructed to allow however, management activities that (3) agricultural land development is no movement of small animals (USCBP reduce threats to the species make longer occurring; (4) urbanization is not 2008a, pp. 1–4 to 1–6 and Appendix B; important contributions to the status of occurring in Yuha Desert, East Mesa, or USCBP 2008b, pp. 2–5 and 8–9); thus, the species at a local or regional level. West Mesa; and (5) the Mexican we do not anticipate the fence itself to Moreover, for implementation of the Government is providing protections to completely hinder flat-tailed horned Interagency Conservation Agreement to flat-tailed horned lizards. lizard movement (see ‘‘Barriers and be successful, each signatory agency Our Response: As described in our Small Populations’’ under Factor E). should implement its share of the analysis above, we agree with the Additionally, with respect to the Yuha Rangewide Management Strategy (see commenter’s statements in general. The Desert Management Area, this area was also the Management and Populations mitigation (compensation or off-setting) selected for management protections of in the Background section, and the measures associated with the flat-tailed horned lizards because it is Description of Specific Populations Rangewide Management Strategy are likely to support high densities of section for further discussion). important to consolidating the lizards (i.e., 0.7 individuals per ha (0.3 Comment 16: One commenter stated Management Areas under the control of per ac), which is a conservative that flat-tailed horned lizards should not signatory agencies. We agree monitoring estimate). Moreover, as mentioned be listed as a threatened species because data indicate that flat-tailed horned above, the border fence is likely a there has been sufficient management in lizard populations in the surveyed semipermeable barrier for small species place over the past 10 years. The Management Areas are not low and are such as flat-tailed horned lizard, commenter believes management efforts not declining. We also agree that

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agricultural and urban development are references cited, as well as others, is Authority: The authority for this action is not significant threats to the species, as available upon request from the section 4(b)(6)(B)(ii) of the Endangered discussed under Factor A, and that the Carlsbad Fish and Wildlife Office (see Species Act of 1973, as amended (16 U.S.C. protections afforded to the species by ADDRESSES). 1531 et seq.). Mexican laws are not inadequate. Dated: February 25, 2011. Author References Cited Daniel M. Ashe, A complete list of all references cited The primary authors of this document Acting Director, Fish and Wildlife Service. in this document is available on the are staff members at the Carlsbad Fish [FR Doc. 2011–5411 Filed 3–14–11; 8:45 am] ADDRESSES Internet at http://www.regulations.gov. and Wildlife Office (see BILLING CODE 4310–55–P Additionally, a complete list of all above).

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