Vol. 76 Wednesday, No. 193 October 5, 2011

Part IV

Department of the Interior

Fish and Wildlife Service 50 CFR Part 17 Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Cactus Ferruginous Pygmy- as Threatened or Endangered With Critical Habitat; Proposed Rule

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DEPARTMENT OF THE INTERIOR questions regarding this finding to the stating that we were proceeding with a above address. review of the petition. Fish and Wildlife Service The petitioners described three FOR FURTHER INFORMATION CONTACT: potentially listable entities of the 50 CFR Part 17 Steve Spangle, Field Supervisor, pygmy-owl: (1) An Arizona distinct Arizona Ecological Services Office (see population segment (DPS) of the pygmy- [FWS–R2–ES–2011–0086; MO 92210–0– ADDRESSES); telephone 602–242–0210; 0008] owl; (2) a Sonoran Desert DPS of the or by facsimile 602–242–2513. If you pygmy-owl; and (3) the western use a telecommunications device for the subspecies of the pygmy-owl, which Endangered and Threatened Wildlife deaf (TDD), please call the Federal and Plants; 12-Month Finding on a they identified as Glaucidium ridgwayi Information Relay Service (FIRS) at cactorum. As an immediate action, the Petition To List the Cactus 800–877–8339. Ferruginous Pygmy-Owl as Threatened petitioners requested that we or Endangered With Critical Habitat SUPPLEMENTARY INFORMATION: promulgate an emergency listing rule for the pygmy-owl. In our June 25, 2007, AGENCY: Fish and Wildlife Service, Background response letter to the petitioners, we Interior. Section 4(b)(3)(B) of the Endangered described our evaluation of the need for ACTION: Notice of 12-month petition Act (Act) (16 U.S.C. 1531 et emergency listing and stated our finding. seq.) requires that, for any petition to determination that emergency listing revise the Federal Lists of Endangered was not warranted for the pygmy-owl. SUMMARY: We, the U.S. Fish and and Threatened Wildlife and Plants that We also stated that the designation of Wildlife Service (Service), announce a contains substantial scientific and critical habitat would be considered if 12-month finding on a petition to list commercial information that listing a listing of the pygmy-owl was found to the cactus ferruginous pygmy-owl species may be warranted, we make a be warranted. (Glaucidium brasilianum cactorum) as finding within 12 months of the date of In the Federal Register of June 2, 2008 threatened or endangered and to receipt of the petition. In this finding, (73 FR 31418), we published a 90-day designate critical habitat under the we determine whether the petitioned finding in which we determined that the petition presented substantial scientific Act of 1973, as action is: (1) Not warranted, (2) and commercial information to indicate amended (Act). Additionally, the warranted, or (3) warranted, but that listing the pygmy-owl may be petition requested that we recognize and immediate proposal of a regulation warranted. A more thorough summary list a western subspecies of the cactus implementing the petitioned action is of previous Federal actions related to ferruginous pygmy-owl (Glaucidium precluded by other pending proposals to the pygmy-owl can be found in the June ridgwayi cactorum), or, alternatively, determine whether species are two potential distinct population 2, 2008 90-day finding (73 FR 31418). threatened or endangered, and Following the publication of our 90- segment (DPS) configurations. After expeditious progress is being made to review of all available scientific and day finding on this petition, we initiated add or remove qualified species from a status review to determine if listing of commercial information, we find that the Lists of Endangered and Threatened Glaucidium ridgwayi cactorum is not a the pygmy-owl was warranted. During Wildlife and Plants. Section 4(b)(3)(C) of our status review, we solicited and valid taxon, and, therefore, not a listable the Act requires that we treat a petition entity under the Act. Additionally, received information from the general for which the requested action is found public and other interested parties on using the currently accepted taxonomic to be warranted but precluded as though classification of the pygmy-owl the status of the pygmy-owl. We resubmitted annually on the date of consulted with experts, agencies, (Glaucidium brasilianum cactorum), we such finding. Therefore, a new finding find that listing the pygmy-owl is not countries, and tribes to gather pertinent is to be made within 12 months and information, and ensure that experts warranted at this time throughout all or subsequently thereafter until we take a significant portion of its range, and affected parties were aware of the action on a proposal to list or withdraw status review and of the opportunity to including the petitioned and other our original finding. We must publish potential DPS configurations. However, provide input. We identified, contacted, these 12-month findings in the Federal and consulted with a diverse group of we ask the public to submit to us at any Register. time any new information concerning experts and interested persons in an the or status of the pygmy- Previous Federal Actions effort to ensure that we gathered and owl, as well as any new information on evaluated the best available scientific the threats to the pygmy-owl or its On March 20, 2007, we received a and commercial information on this habitat. petition dated March 15, 2007, from the subspecies to inform our 12-month Center for Biological Diversity and finding. DATES: The finding announced in this Defenders of Wildlife (petitioners) On December 12, 2009, we received a document was made on October 5, 2011. requesting that we list the cactus 60-day Notice of Intent to Sue from the ADDRESSES: This finding is available on ferruginous pygmy-owl (Glaucidium petitioners for failure to produce a the Internet at http:// brasilianum cactorum) (pygmy-owl) as a timely 12-month finding on their www.regulations.gov at Docket Number threatened or endangered species under petition. They subsequently filed suit on FWS–R2–ES–2011–0086. Supporting the Endangered Species Act (Act) (CBD February 17, 2010, in the U.S. District documentation we used in preparing and DOW 2007). Additionally, the Court for the District of Arizona. That this finding is available for public petition requested the designation of complaint was subsequently inspection, by appointment, during critical habitat concurrent with listing. consolidated in the U.S. District Court normal business hours at the U.S. Fish The petition clearly identified itself as for the District of Columbia along with and Wildlife Service, Arizona Ecological a petition and included the another case filed by the Center for Services Office, 2321 West Royal Palm identification information, as required Biological Diversity and thirteen cases Road, Suite 103, Phoenix, AZ 85021– in 50 CFR 424.14(a). We acknowledged filed by Wild Earth Guardians, all 4951. Please submit any new the receipt of the petition in a letter to related to petition finding deadlines. information, materials, comments, or the petitioners dated June 25, 2007, The court in the consolidated case

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approved two settlement agreements ‘‘endangered species’’ and ‘‘threatened attempt to present the most current between the parties on September 9, species,’’ which requires analysis of taxonomic classifications, but 2011. In re Endangered Species Act whether a ‘‘species’’ is endangered or discrepancies among checklists Deadline Litigation, Misc. Action No. threatened within ‘‘a significant portion demonstrate that there is scientific 10–377 (EGS), MDL Docket No. 2165 of its range’’ (see Significant Portion of debate and disagreement over some (D.D.C. Sept. 9, 2011) (Docs. 55 & 56). the Range section below). Finally, we accepted taxonomic designations. The settlement agreements stipulate that make our finding with regard to the Taxonomic changes within these the Service will submit to the Federal petitioned action and our evaluation as checklists generally occur as a result of Register a proposed listing rule or a not described above. a proposal to change the existing warranted finding for the cactus Species Information taxonomy. Lack of reference to a ferruginous pygmy-owl no later than the proposed taxonomic change within end of Fiscal Year 2011, which is Description these checklists cannot be interpreted as September 30, 2011. The pygmy-owl is in the order rejection (or acceptance) of a proposed This notice constitutes a 12-month Strigiformes and the family Strigidae. It change. It may simply mean a proposal finding for the petition to list the is a small , approximately 17 has not been submitted or evaluated. pygmy-owl as threatened or endangered. centimeters (cm) (6.75 inches (in)) long. Absolute reliance on one or more of We base our finding on a review of the Generally, male pygmy- average 58 these avian checklists, absent best scientific and commercial grams (g) to 66 g (2.0 to 2.3 ounces (oz)) consideration of recent studies, would information available, including all and females average 70 g to 75 g (2.4 to be arbitrary on the part of the Service. substantive information received during 2.6 oz) (AGFD 2008b, p. 3; Proudfoot The Service has the responsibility for our status review. and Johnson 2000, p. 16; Johnsgard deciding what taxonomic entities are to In this finding, we first provide 1988, p. 159). The pygmy-owl is reddish be protected under the Act, based on the background information on the biology brown overall, with a cream-colored best available scientific information. We of the pygmy-owl. Included in this belly streaked with reddish brown. address any conflicting information or background is our analysis of the Color may vary, with some individuals conflicting expert opinion by carefully petitioner’s request that we recognize a being more grayish brown (Proudfoot evaluating the underlying scientific western subspecies of the pygmy-owl and Johnson 2000, pp. 15–16). The information and weighing its reliability (Glaucidum ridgwayi cactorum), which crown is lightly streaked, and a pair of and adequacy according to the represents a proposed change in the dark brown or black spots outlined in considerations of the Act and our taxonomic classification of the pygmy- white occurs on the nape, suggesting associated policies and procedures. owl. Then, we consider each of the five ‘‘eyes,’’ leading to the name ‘‘Cuatro When we previously listed the factors listed in section 4(a)(1) of the Ojos’’ (four eyes), as it is sometimes pygmy-owl as endangered in 1997 (62 Act. For each factor, we first determine called in Mexico (Oberholser 1974, p. FR 10730; March 10, 1997), and in all whether any negative impacts appear to 451). The species lacks ear tufts, and the subsequent regulatory and legal actions, be affecting the pygmy-owl anywhere in eyes are yellow. The tail is relatively we followed the currently accepted the subspecies’ range, and whether any long for an owl and is reddish brown in taxonomic classification, Glaucidium of these impacts rise to the level of color, with darker brown bars. Pygmy- brasilianum cactorum. We considered threats such that the pygmy-owl is owls have large feet and talons relative G. b. cactorum to occur from lowland endangered or threatened throughout its to their body size. central Arizona south through western range, according to the statutory Mexico to the Mexican states of Colima standard. Taxonomy and Michoaca´n, and from southern After the rangewide assessment, we The petitioners requested that we Texas south through the Mexican states evaluate the validity of the petitioned recognize a change in the taxonomic of Tamaulipas and Nuevo Leon, distinct population segments (DPSs), as classification of the pygmy-owl (CBD consistent with most of the well as other potential DPS and DOW 2007, pp. 1–2). In considering contemporary literature (Johnsgard configurations suggested by information taxonomic data, the Service relies ‘‘on 1988, p. 159; Millsap and Johnson 1988, submitted during the status review or by standard taxonomic distinctions and the p. 137; Oberholser 1974, p. 452; the ecology, occurrence, and biological expertise of the Department Friedmann et al. 1950, p. 145), and the distribution of the pygmy-owl. This and the scientific community last American Ornithologist Union analysis determines whether any of the concerning the relevant taxonomic (AOU) list that addressed avian DPS configurations meet the criteria for group’’ (50 CFR 424.11(a)) and on ‘‘the classification to the subspecies level discreteness and significance under our best available scientific and commercial (AOU 1957) (Figure 1). The AOU DPS policy (see Distinct Vertebrate information’’ (50 CFR 424.11(b)). The checklist is generally accepted as the Population Segment section below). We use of specific taxonomic data is at the primary authority for avian taxonomic then evaluate whether there is a discretion of the Service, as long as the classification, and the 1957 AOU significant portion of the pygmy-owl’s information is reliable and meets the checklist description is the currently range that warrants further evaluation, above standards. With regard to the accepted taxonomic classification of the consistent with the Act’s definitions for pygmy-owl, existing avian checklists pygmy-owl at the subspecies level.

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The petitioners requested a revised information in these existing lists and needs additional work to resolve current taxonomic consideration for the pygmy- other literature as we evaluated the questions (Johnson and Carothers owl based on Proudfoot et al. (2006a, p. petitioned taxonomic classification. The 2008b, pp. 5–6; Robbins 2008, p. 1; 9; 2006b, p. 946) and Ko¨nig et al. (1999, 1957 AOU checklist is the last AOU Voelker 2008, p. 1). pp. 160, 370–373), classifying the checklist that described subspecies. Taxonomic nomenclature for the northern portion of Glaucidium Subsequent AOU checklists have pygmy-owl has changed over time. brasilianum’s range as an entirely limited their descriptions to the species Originally called Glaucidium separate species, G. ridgwayi, and level only and are, therefore, not helpful ferrugineum in 1872 by Coues (Coues recognizing two subspecies of G. in our evaluation. 1872, p. 370), the pygmy-owl has also ridgwayi—G. r. cactorum in western In our 90-day finding for this petition been known as G. ferrugineus (Aiken Mexico and Arizona and G. r. ridgwayi (73 FR 31418), we indicated that the 1937, p. 29) and G. phalo(a)enoides in eastern Mexico and Texas (Figure 1). petition presented reliable and (Fisher 1893, p. 199; Gilman 1909, p. Other recent studies proposing or substantive information that a 115, Swarth 1914, p. 31; Kimball 1921, supporting the change to G. ridgwayi for taxonomic revision may be warranted. p. 57). Since the 1920’s, the pygmy-owl the northern portion of G. brasilianum’s The suggested taxonomic change is has been classified as G. brasilianum range have been published in the past based on recently published (van Rossem 1937, p. 27; Bent 1938, p. 15 years (Heidrich et al. 1995, p. 2, 25; recommendations (Proudfoot et al. 435; Peters 1940, p. 130; Brandt 1951, p. Navarro-Siguenza and Peterson 2004, 2006a, p. 9; 2006b, p. 946; Ko¨nig et al. 653; Sutton 1951, p. 168). We will focus p. 5). 1999, pp. 160, 370–373) to revise our discussion at the subspecies level Groups classified within species, such pygmy-owl taxonomy. Various other since the petitioned entity is at the as subspecies, are important in the publications also provide evidence that subspecies level of classification. As discussion of biodiversity because they the taxonomic status of the pygmy-owl such, we will not evaluate or discuss represent the evolutionary potential has not been resolved (Proudfoot and whether the appropriate species within a species. Recognizing this, a Johnson 2000, pp. 4–5; Ko¨nig et al. classification is G. brasilianum or G. number of existing lists of threatened, 1999, p. 373; Phillips 1966, p. 93; ridgwayi. endangered, or special status species Buchanan 1964, p. 107). Information The petitioners asked the Service to include subspecific groups (Haig et al. received during our status review also recognize a subspecies, Glaucidium 2006, p. 1585). We considered the indicates that pygmy-owl taxonomy ridgwayi cactorum, described by

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Proudfoot et al. (2006a, pp. 9–10; 2006b, Mexico, the Lower Rio Grande Valley of r. cactorum) and northeastern (G. r. p. 2, 9) as the listable entity in the Texas, and northeastern Mexico, for a ridgwayi) extensions of the range of G. petition. The primary difference general distribution that runs from b. cactorum. Specifically, the petition between the petitioned subspecies and central Mexico northward on both sides describes the range of the suggested the currently accepted description of G. of the Sierra Madre mountains into subspecies, G. r. cactorum, as extending brasilianum cactorum is the latter’s Arizona and Texas. The range of the from Arizona on the north through the more extensive distribution to the south proposed G. r. cactorum does not extend States of Sonora and Sinaloa in Mexico and east (Figure 1). The range of the G. as far south as G. b. cactorum. The two (Figure 2). b. cactorum subspecies we originally G. ridgwayi subspecies proposed by the listed in 1997 is Arizona, northwestern petition encompass the northwestern (G.

Our analysis of whether to accept the cactorum subspecies, the distribution of pygmy-owl and was described from a petitioners’ proposed Glaucidium some of which generally match the ‘‘giant cactus grove between Empalme ridgwayi cactorum subspecies as a petitioned subspecies. Therefore, the and Guaymas * * * Sonora, Mexico’’ listable entity includes an evaluation of delineation of a cactorum subspecies as (van Rossem 1937, p. 27). Van Rossem whether there are historical or current petitioned is not a new classification, restricted this new subspecies to descriptions or studies of the proposed but one that has been described northwestern Mexico and Arizona subspecies that would support the previously in the literature under G. (Figure 3). Van Rossem also included a description of the petitioned subspecies brasilianum. more southern and eastern subspecies, based on Proudfoot et al. (2006a, With regard to existing literature, van ridgwayi, that was described as 2006b). A number of subspecies of G. Rossem (1937, pp. 27–28) described the occurring in southern Mexico and brasilianum have been described or earliest cactorum subspecies that central America, but also Texas (van suggested (Proudfoot and Johnson 2000, approximates the distribution of the Rossem, 1937, pp. 27–28). He p. 4; Friedmann et al. 1950, pp. 145– petitioned subspecies. This was a newly specifically excluded the Texas 147), including various descriptions of a described subspecies of ferruginous population from cactorum, about which

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he wrote ‘‘they approximate very closely indicated that cactorum extended only state of Sinaloa is the southern extent of the measurements and tail characters of to the Sonora and Sinaloa border in the range, while Ko¨nig et al. (1999, p. cactorum * * * in color they are best Mexico (Figure 3), perhaps excluding 373) extend the distribution of cactorum referred to ridgwayi’’ (van Rossem 1937, Nayarit, because his 1937 publication into Nayarit and Jalisco in western pp. 27–28; italics added). The 1944 indicates that the specimen from Mexico (Figure 3). Freethy (1992, p. AOU checklist accepted this Nayarit was not typical (van Rossem 121) simply states that western Mexico classification and described its 1937, p. 28). Karalus and Eckert (1971, is the southern limit of cactorum. distribution as southern Arizona to p. 223) give a southern distribution for Clements (2007, p. 171) recognizes the Nayarit, in western Mexico (AOU 1944, cactorum of western and northwestern cactorum subspecies, but gives no p. 50) (Fig. 3). However, in a later Sonora (Figure 3). Proudfoot et al. distribution. publication van Rossem (1945, p. 111) (2006a, p. 9; 2006b, p. 7) indicate the BILLING CODE 4310–55–P

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BILLING CODE 4310–55–C all five experts indicated that, while (2008, p. 2) indicates that, ‘‘within the The chronology described in the there are certain aspects of the , it is clear that the Arizona previous paragraph, which excludes the information presented in the petition group is much different from the Texas currently accepted distribution of that support acceptance of the group and should not be considered as Glaucidium brasilianum cactorum, petitioned entity, there is insufficient one group. What is less clear, however, focuses on descriptions in the literature information regarding how to define a is where exactly to draw the boundary which generally approximate the distinct subspecies. Additional work is between the two subspecies * * *. It petitioned description of G. ridgwayi needed to clarify the distribution of the would be informative to look at other cactorum, and there is consensus that subspecies, especially in regards to the characteristics (morphology, behavior, cactorum extended northward into southern boundary (Voelker 2008, p. 1; geographic distribution) and see how Arizona. However, it is evident there is Cicero 2008, p. 2; Robbins 2008, p. 1; well they fit with the patterns provided inconsistency regarding the southern Oyler-McCance 2008, pp. 1–2; by the genetic data. Only then, using all extent of the subspecies. With the Dumbacher 2008, pp. 2–8). A summary those characteristics, would it be exception of van Rossem (1937, pp. 27– of their comments is presented below. prudent to make a decision.’’ 28), who uses morphological Dumbacher (2008, p. 7) provided a Robbins (2008, p. 1) indicated that characteristics to describe the summary of considerations in response work on a molecular-based phylogeny of subspecies, most of the above to our request for input on this issue: New World pygmy-owls is about to be descriptions of the cactorum subspecies ‘‘In summary, Proudfoot et al. 2006a completed that will inform this issue. do not indicate why they have ascribed and 2006b do not provide a critical test He suggested that acceptance of the the subspecies to the ranges indicated in for the subspecies Glaucidium ridgwayi petitioned entity be delayed until this these publications. Ko¨nig et al. (1999, p. ridgwayi or G.r. cactorum or their work has been published. However, the 373) simply uses the morphological geographical ranges. The data are study to which Robbins refers will focus characters of van Rossem (1937, pp. 27– consistent with current subspecies on species-level analyses, and it may 28). Ko¨nig et al. (1999, entire) and names in that they show: (1) Isolation by not provide additional information Proudfoot et al. (2006a; 2006b, entire) distance across the range, albeit with regarding the distribution of subspecies do classify cactorum using genetic data, larger genetic breaks in the region that and, as of the date of this finding, has but draw different conclusions with corresponds with the subspecies names not yet been published. regard to the southern boundary. The [as described by van Rossem 1937]; (2) Recently, the Committee on incremental southward extension of the and significant variation among major Classification and Nomenclature on various cactorum ranges may provide geographical areas that broadly North and Middle American (the some support for the idea of a clinal correspond to present subspecies names Checklist Committee) of the AOU pattern of differentiation in which [van Rossem 1937]. However, it is not considered a proposal to separate genetic and morphological differences clear: (1) Where exactly the subspecies Glaucidium brasilianum ridgwayi as a occur in an incremental manner, as boundaries occur; (2) whether the distinct species, but rejected that opposed to more abrupt changes that are boundary will be geographically distinct proposal, citing the need to wait for more likely to represent a boundary or correspond to characters used in the additional work (AOU 2009). between two distinct subspecies original subspecies designation, such In fairness to Proudfoot and his groupings. The data presented in the that the two groups would qualify for collaborators, their two 2006 studies are petition (Proudfoot et al. 2006a; 2006b, subspecies under the 75 percent rule [75 more general in nature and did not have entire) are not sufficient to clarify the percent of individuals in a new the objective of defining pygmy-owl groupings in the literature, nor does it subspecies (or region) are diagnosably classification to the subspecies level. In allow us to determine if the subspecies different from the other possible addition, Proudfoot and his fellow ranges are distinct because there is a subspecies]; or (3) whether a broad authors, similar to the authors of many lack of adequate sampling in southern hybrid zone or cline would be other publications related to pygmy-owl and eastern Mexico. The uncertainty of discovered that might call the two taxonomy, pointed out the need for the southern boundary would suggest subspecies into question. Further data additional work to clarify the taxonomic that additional sampling is needed to are needed to critically test the validity classification of pygmy-owls. Therefore, refine this portion of the range of of the subspecies and to identify the when we consider the recent cactorum. In the presence of unresolved most appropriate geographic boundary information provided by Proudfoot et al. inconsistencies, the Service relies upon between them. Proudfoot et al. (2006b) (2006a; 2006b, entire) and Ko¨nig et al. the ‘‘standard taxonomic distinctions make a plea for more data in critical (1999, entire), in combination with the (50 CFR 424.11(a)); in this case, the areas, such as between Sonora and historical descriptions of distributions currently accepted taxonomic Sinaloa, and I would argue further south for the subspecies cactorum, there is classification (AOU 1957). as well.’’ evidence of a general nature that the In addition to reviewing historical Cicero (2008, p. 2) adds, ‘‘On the basis petitioned subspecies may have merit. and current descriptions of the of these data, I would argue that Arizona However, after reviewing the best subspecies, we requested review and and Texas populations should be available information, we find that input on the issue of taxonomic managed as separate units. However, uncertainty and inconsistency exists classification of the petitioned entity further study of the variation in with regard to the delineation of the from 10 individuals with biological morphology and plumage (the range of these subspecies. expertise and background in this issue. characters originally used to describe The peer reviewers who provided Of the 10 we consulted, 5 provided cactorum) is needed before we can information to the Service regarding this comments on specific questions we reliably apply names to these issue represent respected experts with asked regarding the issues of taxonomic populations. Thus, in my opinion, the considerable knowledge of the current classification, genetic differentiation, molecular data provided by Proudfoot et science regarding avian taxonomy and and genetic diversity based on recent al. (2006a and 2006b) do not clarify classification. They point out that a and historical studies and publications subspecific limits and ranges in North combination of factors, including related to pygmy-owl taxonomic American populations of G. morphological, vocal, and genetic, need classification. Information submitted by brasilianum’’. Similarly, Oyler-McCance to be considered in greater depth, with

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additional sampling, to determine if the relatively detailed information on National Wildlife Refuge, Organ Pipe petitioned taxonomic classification pygmy-owl distribution in the United Cactus National Monument, and should be accepted, and we are in States and Sonora, Mexico. The northern Sonora that are not in agreement with these comments. Given following is a description of the proximity to ‘‘cultivated riparian’’ or the uncertainty and lack of clarification available information we have related to naturally occurring hydro- or found in the best available scientific and the distribution of the pygmy-owl. mesoriparian (wet riparian) habitats. commercial information, we rely on the The cactus ferruginous pygmy-owl is Two members of the public provided ‘‘biological expertise of the Department the northernmost subspecies of the extensive information in support of the and the scientific community ferruginous pygmy-owl. This subspecies idea that pygmy-owls have never been concerning the relevant taxonomic was originally described as being common in Arizona; therefore, the group’’ (50 CFR 424.11(a)). common in the lower Rio Grande River current low numbers and reduced In summary, we find that there is in southern Texas (Oberholser 1974, p. distribution are not sufficient reason to considerable uncertainty as to whether 452) and along the Salt and Gila Rivers determine that the pygmy-owl is the genetic differentiation found at the in central Arizona (Fisher 1893, p. 199; endangered in Arizona (James 2008, pp. far ends of the pygmy-owl’s distribution Breninger 1898, p. 128; Gilman 1909, p. 8–10; Parker 2008, pp. 2–10). This represented by Arizona and Texas are 148). In Arizona and Texas, apparent conclusion is based on the historical adequate to define the eastern and range and population declines have records from early naturalists and western distributions as separate occurred, reducing the current ornithologists regarding their subspecies. These differences may distribution of the pygmy-owl in these observations or collections of pygmy- simply represent isolation by distance areas (Oberholser 1974, p. 452; Monson owls or their nests or , or the lack with a clinal gradation of genetic and Phillips 1981, p. 72; Proudfoot and thereof. Specifically, this information differentiation between the two Johnson 2000, p. 3). Historical records points out that a number of early extremes of the range, which would be for the pygmy-owl in Arizona span at naturalists or ornithologists that made inconsistent with the existence of two least five counties in southern and trips of various lengths and in various different subspecies. Therefore, the best south-central Arizona, including locations in Arizona where pygmy-owls available scientific and commercial Maricopa, Pima, Pinal, Santa Cruz and would have been expected to occur did information does not suggest that Yuma Counties (Johnson et al. 2003, p. not make mention of observing pygmy- genetic differentiation reported by 394). Most of the historical (pre-1900) owls in their trip reports (James 2008, Proudfoot et al. (2006a; 2006b, entire) and recent (post-1990) records are from pp. 46–48; Parker 2008, pp. 6–8). We and Ko¨nig et al. (1999, entire) supports Pima County. Between 1872 and 1971, appreciate the effort and research their proposed Glaucidium ridgwayi a total of 56 published records or represented by this information. It cactorum subspecies classification at specimens were recorded for Arizona. provides an excellent summary of this time. Future work and studies may Of those, almost half (27) were from historical ornithological efforts in clarify and resolve these issues, but, in Pima County (Johnson et al. 2003, pp. Arizona. In assessing the information the meantime, we will continue to use 392–395). Although the pygmy-owl was provided, we must determine if it is the currently accepted distribution of G. historically recorded primarily from comparable to the information currently brasilianum cactorum as described in lowland riparian habitats, all recent available on pygmy-owl numbers and the 1957 AOU checklist and various records are from upland and distribution in Arizona. Current other publications (Johnsgard 1988, p. xeroriparian (vegetation community in information comes from extensive 159; Millsap and Johnson 1988, p. 137; drainages associated with seasonal or surveys focused on locating only Oberholser 1974, p. 452; Friedmann et intermittent water) Sonoran desertscrub pygmy-owls using tape-playback or call al. 1950, p. 145). The Service accepted (Abbate et al. 2000, pp. 15–16, Service imitation to locate the owls. We can find this information under the previous 2009b, p. 1: 2011, p. 1). no evidence from the information listing of the pygmy-owl (62 FR 10730). Some information provided by the provided that this same effort or We, therefore, reject the petitioned public suggested that the pygmy-owl is methodology was used to locate pygmy- listing of a western subspecies of an obligate wet riparian species in owls in the historical record; thus pygmy-owl, G. r. cactorum, as an south-central Arizona and a preferential comparison with current surveys is not insufficiently supported taxonomic wet riparian species in southern appropriate. subspecies at this time. Arizona, tying its distribution to these We do not discount the ability of early The following discussion will types of areas. In addition, the naturalists and ornithologists to find examine the potentially listable entities information states that recent records in and identify pygmy-owls. However, of Glaucidium brasilianum cactorum, upland habitats have occurred primarily finding pygmy-owls was not the the currently recognized subspecies of in areas associated with ‘‘cultivated objective of the trips reported in the pygmy-owl. riparian’’ habitats resulting from the literature, and unfortunately, most of human influences of irrigation and these early reports do not contain Distribution and Status ornamental plantings, such as in enough information for us to determine The currently accepted distribution of suburban areas of Tucson (Johnson and that the effort was adequate to find the pygmy-owl is described as south Carothers 2008b, pp. 13–14). We agree pygmy-owls if they were present or that central Arizona and southern Texas in that riparian ecosystems provide the absence of documentation of pygmy- the United States, south through the important pygmy-owl habitat within its owls truly means that no pygmy-owls Mexican States of Sonora, Sinaloa, range. However, we disagree with the were encountered. Additional Nayarit, Jalisco, Colima, and Michoaca´n suggestion that pygmy-owls are riparian information received from the public on the west and Nuevo Leon and obligates, and thus limited in points out the problems in interpreting Tamaulipas on the east (Figure 1). occurrence to these areas. For example, these early reports, ‘‘While certainly Available information on the specific there are numerous recent locations in instructive as to the critical value of distribution of the pygmy-owl within which pygmy-owls were detected in surface water diversions, irrigation, and this general area is not comprehensive, Sonoran desert uplands and semi-desert agriculture to Cactus ferruginous pygmy especially in the southern portions of grasslands of southern Pinal County, owls, lack of necessary specific Mexico. As described below, we have Avra Valley, Altar Valley, Cabeza Prieta information prevents Breninger’s 1898

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account from serving as a source of systematic surveys throughout Pima no quantifiable information on which to support for the petitioner’s claim that County. To date, they have conducted base trends in pygmy-owl populations. this owl was historically common across 383 surveys at 152 locations in Pima Consequently, we must base our the lowlands of central and southern County with no detections (Pima evaluation of the current pygmy-owl Arizona. This is because Breninger County 2008, p.1). Some of the above status on the best available scientific neither shows how much time he spent surveys, and other negative surveys and commercial data, which is the in the field nor the locations he actually conducted throughout Arizona since information that does, at least, provide visited along either the Salt and Gila 1997, occurred in areas where the some ability to quantify pygmy-owl Rivers that caused him to conclude that pygmy-owl was historically located. population numbers. Regardless of the Cactus ferruginous pygmy owls were This provides strong evidence that the lack of quantified historical data, the then ‘‘of common occurrence’’ ‘‘among current range of the pygmy-owl in early records found in the literature give the growth of cottonwood’’ that fringed Arizona has contracted. us some idea of the historical both on a highly localized basis’’ (Parker Currently in Arizona, the pygmy-owl distribution of the pygmy-owl in 2008, pp. 3–4). is found only in portions of Pima and Arizona that, when compared to the While early records provide Pinal Counties. The Arizona Breeding current distribution, has unquestionably information that shows the range of the Bird Atlas reports confirmed been reduced. pygmy-owl has contracted in Arizona, occurrences of the pygmy-owl in only In Texas, the pygmy-owl was formerly this conclusion relies on information at three blocks distributed in Pima and common in the Rio Grande delta. a large scale and is not dependent on Pinal Counties (Arizona Breeding Bird Griscom and Crosby (1926, p. 18) specific population numbers, only Atlas (ABBA) 2005, p. 219). Twelve reported that the pygmy-owl was presence or absence. The logical other blocks recorded probable (3) or considered a ‘‘common breeding assumption may follow that pygmy-owl possible (9) occurrences, but none species’’ in the Brownville region of numbers are likely reduced as well. occurred outside of Pima and Pinal southern Texas. Even as late as 1950, However, these early records do not Counties (ABBA 2005, p. 219). Recent Friedman et al. (1950, p. 145) have enough specific information for us surveys indicate that probably fewer considered the pygmy-owl to be ‘‘a very to quantify historical pygmy-owl than 50 adult pygmy-owls exist in the common breeding bird.’’ However, population numbers in a way that state, with 10 or fewer nest sites on an Oberholser (1974, pp. 451–452) allows comparison to our current annual basis (Abbate et al. 2000, pp. 15– indicates that agricultural expansion information. Glinski (1998, p. 3) 16, AGFD unpublished data). However, and subsequent loss of native woodland provides a summary of this issue in The since the pygmy-owl was delisted in and thornscrub habitat, beginning in the Raptors of Arizona, ‘‘From the 2006 (71 FR 194521; April 14, 2006), 1920s, preceded the rapid demise of the perspective of the variety and numbers surveys, monitoring, and other research pygmy-owl populations in the Rio of raptors, what did Arizona’s landscape on pygmy-owls has declined. Limited Grande delta. By the 1970s, the pygmy- harbor two centuries ago? Is the answer survey and monitoring in Arizona from owl was encountered only rarely in to this question in the early literature? 2009 to 2011 documented that pygmy- Texas. Unfortunately, no. Detailed records that owls still occupy historical locations in Nonetheless, Wauer et al. (1993, pp. accurately depict the status of Arizona the Altar Valley, Avra Valley, and Organ 1074–1076) indicate that private raptors before 1970 are entirely lacking. Pipe Cactus National Monument, all ranches in Kenedy and Brooks Counties The records of early explorers are full of within Pima County (Service 2009b, p. in Texas support a ‘‘large and errors, and later interpretations of them 1; Tibbitts 2011, p. 1; Service 2011, p. apparently thriving population of have added to the problem (G.P. Davis 1). Comprehensive surveys have not ferruginous pygmy-owls.’’ Currently, the 1982).’’ been conducted on the Tohono pygmy-owl is most consistently found We received information from various O’odham Nation (Nation), which is only in the southernmost counties in agencies and municipalities that located in the central portion of both the Texas, mainly in Starr and Kenedy contained survey results from Arizona historical and current distribution of Counties (Tewes 1992, p. 21; Oberholser indicating that the pygmy-owl is likely pygmy-owls in Arizona. However, a 1974, p. 451). More recent work absent from some areas in Maricopa and number of surveys have been completed documents occupancy in Brooks and Pima Counties. Survey data submitted for various utility projects on the Kenedy Counties on the King Ranch and by the USDA Forest Service covering Nation, and the pygmy-owl is known to adjacent ranches in Texas (Proudfoot over 4,050 hectares (ha) (10,000 acres occur there. Distribution of the data 1996, p. 6; Mays 1996, p. 29). (ac)) in a 6-year period on the Tonto from these surveys has been restricted Population estimates in Texas include National Forest in Maricopa County by the Nation and is not available for estimates of greater than 100 owls in detected no pygmy-owls (USFS 2008, p. analysis. There are large areas of Kleberg County (Tewes 1992, p. 24), 654 1). Burger (2008, p.1) indicated that the suitable habitat on the Nation, but the pairs in Kenedy, Brooks, and Willacy Arizona Game and Fish Department information we have indicates that Counties (Wauer et al. 1993, p. 1074), (AGFD) had conducted 3 years of pygmy-owls are patchily distributed, and 745 to 1,823 pygmy-owls on surveys in Maricopa County without just as in other areas of the State, and ranches in Kenedy and Brooks Counties any pygmy-owl detections. Annual occur at similar densities. (Mays 1996, p. 32). pygmy-owl surveys have been In summary, because the early records Recent concern about the populations conducted by the Air Force on the Barry found in the literature provide no basis in Texas has been raised because of an M. Goldwater Range of southwestern for consistent interpretation, the apparent decline in the number of Arizona from 1993 to the present with statements that the pygmy-owl was ‘‘not pygmy-owl nestlings banded as part of no verified pygmy-owl detections (Uken uncommon,’’ ‘‘of common occurrence,’’ an ongoing nest box study in Texas 2008, p. 1). The Pima County and ‘‘fairly numerous’’ in lowland (Proudfoot 2010, p. 1). The numbers of Department of Transportation conducts central and southern Arizona may be as nestlings banded at more than 200 nest pygmy-owl surveys for their capital appropriate as the commenter’s boxes in 2003 and 2004 were 84 and 96 improvement projects. These pygmy- interpretation that the pygmy-owl was respectively. The numbers suggest a owl surveys are associated with specific never common in Arizona. The bottom steady decline from 2004 to 2010, with projects, and do not represent line is that these early records provided 25 and 24 nestlings banded in 2009 and

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2010, respectively (Proudfoot 2010, p. 2008a, p. 6). The most recent monitoring support. Interaction among these 1). This represents an approximate 70 of pygmy-owls in northern Sonora population groups likely varies with percent decline in the number of showed that, in 2010, sites sampled had distance, but pygmy-owls have been nestlings banded over an 8-year period. the highest occupancy rates in the past documented to disperse up to 260 km Proudfoot (2011b, p. 1) indicates this 10 years at nearly 64 percent (Flesch (161 mi.) (AGFD 2008a, p. 5). Individual decline is likely the result of the loss of 2011, p. 1). However, early results from pygmy-owl groups throughout the range suitable habitat around nest boxes due the 2011 monitoring show occupancy of are important to the survival of the to recent hurricanes and fires. Without these same sites at around 50 percent, subspecies as a whole in providing a more comprehensive survey effort in not far from the 10-year low of 45.7 metapopulation support. southern Texas, we cannot definitively percent (Flesch 2011, p. 1). In conclusion, pygmy-owl state that the overall population of In summary, recent surveys and distribution in the United States has pygmy-owls in south Texas matches the research in northwestern Mexico contracted, with pygmy-owls no longer decline of nestlings documented during indicate that numbers and density of found in Maricopa, Cochise, Yuma, and this nest box study. However, it does pygmy-owls are higher in thornscrub Santa Cruz Counties in Arizona, nor in raise our level of concern for this and tropical deciduous forest the Lower Rio Grande Valley in Texas. population. More work is needed in communities of southern Sonora and Despite this range contraction in the Texas to determine the overall Sinaloa than in the Sonoran desertscrub United States, pygmy-owls remain in population status and the extent of and semi-desert grassland vegetation Arizona and Texas. Survey results for habitat loss and fragmentation. It may communities of the Sonoran Desert Arizona indicate that approximately 50 simply be that the pygmy-owls in these Ecoregion (Flesch 2003, pp. 39–42; adult pygmy-owls remain. In addition, areas have moved to adjacent suitable AGFD 2008a, p. 6). there are a few large expanses of habitat as former habitat and the The best available information we Arizona with suitable pygmy-owl associated nest boxes have been have from the literature for the southern habitat that have not been completely destroyed. portion (areas south of Sonora and surveyed or for which pygmy-owl The pygmy-owl occurs in portions of northern Sinaloa) of the pygmy-owl information is not available for eight States in Mexico. The pygmy-owl range indicates that pygmy-owls are one evaluation. Pygmy-owl populations in was thought to be uncommon of the most common birds collected in Texas are estimated to range up to 1,800 throughout much of Sonora (Russell and these areas (Cartron et al. 2000, p. 5; birds, although there have been some Monson 1998, p. 141; Hunter 1988, pp. Enriquez-Rocha et al. 1993, p. 154; declines in pygmy-owl nestlings 1–6). However, recent surveys and Binford 1989, p. 132; Hunter 1988, p. 7; associated with a nest box study in capture efforts have shown that the Johnsgard 1988, p. 161; Oberholser Texas. Pygmy-owls are still found in pygmy-owl commonly occurs in both 1974, p. 451; Schaldach 1963, p. 40). It Sonora and northern Sinaloa, with northern and southern Sonora, but is is important to note, however, that most higher densities reported in thornscrub uncommon or absent in central Sonora of these references apply to the and dry tropical forested areas (Flesch 2003, p. 39; AGFD 2008a, p.6; ferruginous pygmy-owl as a species and compared to the arid desert areas. Based Service 2009a, p. 1). The highest not to the cactorum subspecies on Tewes study (1993, entire), pygmy- densities of pygmy-owls occurred in the specifically. However, the more recent owls still occupy suitable habitat in Sinaloan deciduous forest of southern survey, monitoring, and capture work northeastern Mexico and the pygmy- Sonora (Flesch 2003, p. 42). Flesch discussed above all occurred within the owl’s distribution remains unchanged in (2003, p. 39) documented 438 males, 74 range of the cactorum subspecies. Texas and northeastern Mexico. In females, and 12 pygmy-owls of Tewes (1993, pp. 15–16) provides the addition, it appears that pygmy-owls unknown sex along 1,113 kilometers most current information on pygmy- still occur in the same areas of Mexico (km) (1,780 miles (mi)) of transects in owls in northeastern Mexico. During reported in the literature, suggesting Sonora, and an additional 112 pygmy- surveys in 1991, he estimated 96 that the current distribution is similar to owls incidentally detected. pygmy-owls in association with 142 the historical distribution. The available During capture efforts in 2008, AGFD plots at 12 locations (Tewes 1993, pp. information, although dated, suggests (2008a, p. 6) documented multiple 15–16). He concludes that no published that pygmy-owls remain common in the pygmy-owls commonly responding at empirical evidence suggests any change southern portion of their range. capture sites in the thornscrub and in the distribution of this species in tropical deciduous forests of southern Texas or northeastern Mexico, although Habitat Sonora. In areas of central Sonora the likelihood of finding pygmy-owls is Pygmy-owls are found in a variety of sampled by AGFD, some sites had no low in some historically occupied areas vegetation communities, including pygmy-owl responses, but responses (Tewes 1993, p. 22). Sonoran desertscrub and semidesert increased as sampling moved into In addition, pygmy-owls are not grasslands in Arizona and northern northern Sonora. These results are evenly distributed across their current Sonora, thornscrub and dry deciduous similar to patterns of occupancy range; rather they tend to be patchily forests in southern Sonora south to documented by Flesch (2003, p. 40). distributed across the landscape. Michoaca´n, and Tamaulipan brushland However, it is clear that the number and Pygmy-owl populations, particularly in in Texas and northeastern Mexico. density of pygmy-owls is higher in the the northern portion of its range, likely However, available information thornscrub and deciduous forest function as metapopulations (a group of regarding specific pygmy-owl habitat community types than in the Sonoran spatially separated populations that act elements within these vegetation desert community type. This occurrence at some levels as a single large communities is limited to Arizona, and distribution agrees with population). Genetic and population Texas, and northern Sonora. conclusions found in the literature support for individual groups of pygmy- In Arizona, pygmy-owls rarely occur (Hunter 1988, p. 7; Russell and Monson owls likely occurs as a result of below 300 meters (m) (1,000 feet (ft)) or 1988, p. 141; Shaldach 1963, p. 40). A dispersal. Therefore, habitat above 1,200 m (4,000 ft) (Proudfoot and total of 119 pygmy-owls were captured connectivity among these population Johnson 2000, p. 5), except perhaps by AGFD over 15 days of trapping in groups is important to maintain genetic during dispersal (AGFD 2008b, p. 3). northern Sinaloa and Sonora (AGFD diversity, as well as demographic Historically, in Arizona, the pygmy-owl

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nested in Fremont cottonwood-mesquite growth (Ko¨nig et al. 1999, p. 373). It is also use nest boxes for nesting forests and mesquite bosques often found at the edges of riparian and (Proudfoot 1996, p. 67). (woodlands) associated with major xeroriparian drainages and even habitat Pygmy-owls begin courtship and drainages and their tributaries and the edges created by villages, towns, and advertisement calls early in the year subspecies is considered by some to be cities (Proudfoot and Johnson 2000, p. 5; from January into February. Nest a preferential riparian nesting species. Abbate et al. 1999, pp. 14–23). The selection then occurs, with eggs The pygmy-owl in Arizona also pygmy-owl is a secondary cavity nester, typically being laid from late March into occupies upland Sonoran desertscrub, and nests occur within June. Average clutch size as reported by often associated with xeroriparian areas. holes and natural cavities in giant cacti, Johnsgard (1988, p. 162) for the United Species associated with these areas are but also in trees and even in a sand bank States and Mexico was 3.3 (range 2 to Prosopis spp. (mesquite), Parkinsonia (Flesch 2003, pp. 130–132; Proudfoot 5, n = 43). In Texas, Proudfoot and spp. (palo verde), Acacia spp. (acacia), and Johnson 2000, p. 11; Russell and Johnson (2000, p. 11) report an average Olneya tesota (ironwood), and Monson 1998, p. 141; Johnsgard 1988, p. clutch size of 4.9 (range 3 to 7, n = 58). Carnegiea gigantea (saguaro cactus) 162). Tewes (1992, p. 22) contends that First eggs hatch generally around mid- (Proudfoot and Johnson 2000, p. 5). status and occurrence of the pygmy-owl May, and fledging occurs from late-May In Texas, the pygmy-owl was is related to the availability of nest through June. The first dispersal of historically found in Prosopis spp., cavities. fledglings in Arizona and Texas was Ebenopsis ebano (ebony), and While native and nonnative plant documented as July 24th and August Arundinaria gigantea (cane) along the species composition differs among the 14th, respectively (Proudfoot and Rio Grande River, and a more general various locations within the range of the Johnson 2000, p. 10). Pygmy-owl distribution in riparian trees, brush, pygmy-owl, there are certain unifying juveniles typically disperse at 8 weeks palm, and mesquite thickets (Oberholser characteristics such as the presence of post-fledging. Males typically disperse 1974, p. 451). It is now found primarily vegetation in fairly dense thickets or shorter distances than females. in undisturbed live oak-mesquite forests woodlands; the presence of trees, Dispersal distance ranges from 2.5 to and mesquite brush, ebony, and riparian saguaros, Stenocereus thurberi (organ 20.91 km (1.55 to 13.00 mi) in Arizona areas of the historical Wild Horse Desert pipe cactus), or other columnar cacti (Abbate et al. 2000, p. 21) and 16 to 31 north of Brownsville, Texas (Proudfoot large enough to support cavities for km (9.6 to 18.6 mi) in Texas (Proudfoot and Johnson 2000, p. 5). and Johnson 2000, p. 13). One juvenile In Mexico, the pygmy-owl occurs nesting; and elevations typically below female pygmy-owl in Arizona recently from sea level to 1,200 m (4,000 ft) 1,200 m (4,000 ft) (Swarth 1914, p. 31; dispersed a total of 260 km (161 mi) (Friedmann et al. 1950, p. 145). In Karalus and Eckert 1974, p. 218; between August 2003 and April 2004 Sonora, it was originally common in the Monson and Phillips 1981, pp. 71–72; (AGFD 2008a, p. 5). In Sonora, Mexico, lower Sonoran and Tropical Zones, Johnsgard 1988, Enriquez-Rocha et al. Flesch and Steidl (2007, p. 37) primarily in giant cactus associations 1993, p. 158; Proudfoot 1996, p. 75; documented dispersal distances ranging (van Rossem 1945, p. 111). The Proudfoot and Johnson 2000, p. 5). from 1.1 to 19.2 km (0.7 to 11.5 mi). subspecies is resident throughout most Large trees provide canopy cover and of the desertscrub, tropical thornscrub, cavities used for nesting, and the Pygmy-owls are considered and dry subtropical forests of Sonora, density of mid- and lower-story nonmigratory throughout their range. being most common in the latter vegetation provides foraging habitat and There are winter (November to January) association (Russell and Monson 1998, protection from predators and pygmy-owl locations from throughout p. 141). The pygmy-owl is absent from contributes to the occurrence of prey their historical range in Arizona tropical deciduous forests and higher items (Wilcox et al. 2000, pp. 6–9). (University of Arizona 1995, pp. 1–2; Snyder 2005, pp. 4–5; Abbate et al. vegetation zones in west Mexico, where Life History it is replaced by the least pygmy-owl 1999, pp. 14–17; 2000, pp. 12–13) and (Glaucidium minutissimum) and the Usually, pygmy-owls first nest as also in Texas (Proudfoot 1996, p. 19; northern pygmy-owl (G. gnoma) yearlings (Proudfoot and Johnson 2000, Mays 1996, p. 14). These winter records (Schaldach 1963, p. 40; Buchanan 1964, p. 13; Abbate et al. 1999, pp. 17–19), suggest that pygmy-owls are found pp. 104–105), as well as the Colima and both sexes breed annually within their home ranges throughout the pygmy-owl (G. palmarum) (Howell and thereafter. Territories normally contain year and that they do not migrate Robbins 1995, pp. 19–20). Dry, several potential nest and roost cavities seasonally. The pygmy-owl is primarily subtropical forests provide important from which responding females select a diurnal (active during daylight) with pygmy-owl habitat elements, as nest. Hence, cavities per unit area may crepuscular (active at dawn and dusk) evidenced by pygmy-owls being more be a fundamental criterion for habitat tendencies. common in this vegetation community selection. Historically, pygmy-owls in The pygmy-owl is a perch-and-wait type than in other community types in Arizona used cavities in cottonwood, hunter. It is largely a generalist with Mexico. The dry, subtropical forests mesquite, and ash trees, and saguaro regard to prey and diet. Oberholser comprise the majority of the pygmy- cacti for nest sites (Millsap and Johnson (1974, p. 451) indicated that the pygmy- owl’s southern range in Mexico. The 1988, pp. 137–138). Recent information owl’s diet included lizards, large presence of large trees and columnar from Arizona indicates nests were , rodents, and birds (some as cacti for nesting, and diversity of cover located in cavities in saguaro cacti for large as the owl). In Texas, insects, and prey types, contribute to the value all but two of the known nests reptiles, birds, small , and of dry subtropical forests as pygmy-owl documented from 1996 to 2002 (Abbate amphibians, to a lesser extent, are eaten habitat. et al. 1996, p. 15; 1999, p. 41; 2000, p. by pygmy-owls (Proudfoot and Johnson The pygmy-owl is a creature of edges 13; AGFD 2003, p. 1). Pygmy-owl nests 2000, p. 6). In Arizona, reptiles, birds, found in semi-open areas of thorny in Texas were primarily in mesquite and small mammals, and insects have all scrub and woodlands in association live oak trees (Proudfoot 1996, pp. 36– been recorded in the diet of the pygmy- with giant cacti, scattered patches of 38), and nests in Sonora, Mexico, were owl (Abbate et al. 1999, pp. 35–40). woodlands in open landscapes, mostly nearly always in columnar cacti (Flesch Seasonal and annual variations in diet dry woods, and evergreen secondary and Steidl 2002, p. 6). Pygmy-owls will occur throughout its range (Proudfoot

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and Johnson 2000, p. 6; Abbate et al. evaluated the best available scientific describing the impacts to pygmy-owls 1999, pp. 35–40). and commercial information. was relatively complete. For the The pygmy-owl is commonly mobbed In considering whether the five remaining 73 percent of the pygmy-owl (harassed) by many species of statutory factors in section 4(a) might range in Mexico, information regarding passerines, presumably in response to constitute threats, we must look beyond impacts to pygmy-owls was relatively being a regular predator on those the mere exposure of the species to the sparse. The best available scientific and species (Proudfoot and Johnson 2000, p. factor and determine whether the commercial information indicates that 10; Abbate et al. 1999, pp. 25–26; species responds to the factor in a way the impacts to pygmy-owls in the Hunter 1988, p. 1). The mobbing that causes actual negative impacts to northern portion of their range are behavior of birds can often aid in the species. If there is exposure to a severe. However, the best available locating a well hidden pygmy-owl, as factor, but no response, or only a information indicates that pygmy-owls multiple individuals and species will positive response, that factor is not a in the southern portion of their range often participate in the mobbing and threat. If there is exposure and the remain common and that some of the identify the perch of the pygmy-owl. species responds negatively, the factor threats that are severe in the northern The dark eye-spots on the back of the may be a threat and we then attempt to portion of the species’ range appear to pygmy-owl’s head may act to fend off determine how significant a threat it is. be less severe or non-existent in the mobbing or increase predatory If the threat is significant, it may drive southern portion. Thus we conclude efficiency by confusing prey (Heinrich or contribute to the risk of extinction of that pygmy owls are not threatened 1987 in Proudfoot and Johnson 2000, p. the species such that the species throughout their range, or likely to 10). warrants listing as threatened or become so. The details supporting our Due to their small size and occurrence endangered as those terms are defined conclusion are found in the following in similar habitats as many of their by the Act. This does not necessarily analysis. require empirical proof of a significant predators, pygmy-owls are preyed upon Factor A: Present or Threatened by a variety of species. Documented and threat. The combination of exposure and some corroborating evidence of how the Destruction, Modification, or likely predators in Texas and Arizona Curtailment of Its Habitat or Range include raccoons (Procyon lotor), great species is likely impacted could suffice. horned owls (Bubo virginianus), The mere identification of factors that For this factor, we evaluate available Cooper’s hawks (Accipiter cooperii), could impact a species negatively is not information related to impacts to Harris’ hawks (Parabuteo unicinctus), sufficient to compel a finding that pygmy-owl habitat throughout its range. western screech owls (Megascops listing is appropriate; we require Our evaluation identified general kennicottii), bull snakes (Pituophis evidence that these factors are operative activities affecting or potentially melanoleucus), and domestic cats (Felis threats that act on the species to the affecting pygmy-owl habitat that domesticus) (Abbate et al. 1999, p. 27; point that the species meets the included urbanization, nonnative Proudfoot and Johnson 2000, p. 10). definition of threatened or endangered species invasions, fire, agricultural Pygmy-owls may be particularly under the Act. A species may be development, wood cutting, improper vulnerable to predation and other threatened or endangered based on the grazing, border issues, and off-highway threats during and shortly after fledging intensity or magnitude of one operative vehicle use. However, with the (Abbate et al. 1999, p. 50). Lifespan has threat alone or based on the synergistic exception of the United States and been documented to be 7 to 9 years in effect of several operative threats acting Sonora, Mexico, detailed information the wild (Proudfoot 2009b, p. 1) and 10 in concert. related to these activities is limited, and years in captivity (AGFD 2009, p. 1). Through our five-factor analysis, we we were unable to specifically evaluate identified a number of factors negatively the effects of many of these activities for Summary of Information Pertaining to impacting the pygmy-owl or its habitat. much of the pygmy-owl’s range in the Five Factors Affecting the Pygmy- To determine whether these impacts Mexico. The following discussion Owl Throughout Its Range individually or collectively rise to the presents the best available information Section 4 of the Act (16 U.S.C. 1533) level of threats such that the pygmy-owl regarding these activities and their and implementing regulations (50 CFR is in danger of extinction throughout its effects to pygmy-owl habitat. range, or likely to become so in the 424) set forth procedures for adding Urbanization species to, removing species from, or foreseeable future, we first considered Increasing human populations result reclassifying species on the Federal whether these impacts to the subspecies in expanding urban areas. Urbanization Lists of Endangered and Threatened were causing long-term, range-wide, causes permanent impacts on the Wildlife and Plants. Under section population-scale declines in pygmy-owl landscape that potentially result in the 4(a)(1) of the Act, a species may be numbers, or were likely to do so in the loss and alteration of pygmy-owl determined to be endangered or foreseeable future. Although some of habitat. Residential, commercial, and threatened based on any of the these impacts seem significant infrastructure development replace and following five factors: individually, we found these impacts to (A) The present or threatened be localized in their effects, but not fragment areas of native vegetation destruction, modification, or placing the pygmy-owl in danger of resulting in the loss of available pygmy- curtailment of its habitat or range; extinction throughout its range now or owl habitat and habitat connectivity (B) Overutilization for commercial, in the foreseeable future. In other words, needed to support pygmy-owl dispersal recreational, scientific, or educational the severe impacts were restricted to an and metapopulation function. purposes; area that constitutes a relatively small Increasing human populations require (C) Disease or predation; portion of the pygmy-owl’s range. additional water, and increasing water (D) The inadequacy of existing The detailed information we have on consumption can reduce available regulatory mechanisms; or impacts covers only about 27 percent of surface and ground water needed to (E) Other natural or manmade factors the pygmy-owl’s range. For this area, support pygmy-owl and pygmy-owl affecting its continued existence. which includes Arizona and Texas in prey habitats. Added human presence In making our 12-month finding on the United States, and Sonora and on the landscape can potentially lead to the petition we considered and northern Sinaloa in Mexico, information increased pygmy-owl mortality through

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introduced predators, collisions, etc. downturn and decline in the housing This focuses development, and potential The following discussion presents the market. However, development will barriers or impediments to pygmy-owl available information related to pygmy- likely continue in the future, although movements, in a region that is important owl habitat impacts associated with perhaps at a slower pace than in the for pygmy-owl metapopulation support urbanization. earlier part of this century. We also and other movements such as dispersal. Human population growth results in recognize that economic trends are The Arizona-Sonora border region’s the expansion of urbanization (Travis et difficult to predict into the future. The population growth is expected to reach al. 2005, p. 2). Arizona’s population most recent draft Pinal County 2.1 million (Walker and Pavlakovich- increased by 394 percent from 1960 to Comprehensive Plan (February 2009) Kochi 2003, p. 1) in an area that will 2000, and was second only to Nevada as acknowledges that the county is in the affect cross-border movement by pygmy- the fastest growing State during this middle of the Sun Corridor Megapolitan owls and other important population timeframe (Social Science Data Analysis and proposes four shorter-term growth linkages needed to support the pygmy- Network (SSDAN) 2000, p. 1). Since areas in defining where development owl metapopulation structure. Based on 1990, Arizona’s population has grown will likely occur over the next decade, 1990 human population numbers, the by 44 percent. From 1960 to 2000, but does not discourage growth outside land cover types currently most population growth rates in Arizona of these areas (Pinal County valuable to the pygmy-owl—Mesquite counties where the pygmy-owl occurs, Comprehensive Plan 2009, p. 109). Bosque and Palo Verde-Mixed Cactus— or recently occurred, have varied by Areas within two of the four growth were the most heavily human-populated county, but all are increasing: Maricopa areas (West Pinal and Red Rock) support in the Sonoran Desert Ecoregion. The (463 percent); Pima (318 percent); Pinal historically occupied and recently Mesquite Bosque type makes up 8.2 (54 percent); and Santa Cruz (355 occupied areas. percent of the area, but supports 10.4 percent) (SSDAN 2000). Because most of the pygmy-owl percent of the human population. Urban expansion and human habitat in Texas occurs on private ranch Similarly, the Palo Verde-Mixed Cactus population growth trends in Arizona are lands, the impact of habitat loss and type covers 29 percent of the area, but expected to continue into the future. fragmentation of the remaining pygmy- supports 49.4 percent of the population The Maricopa-Pima-Pinal County areas owl habitat due to urbanization is (Gorenflo 2002, p. 28). of Arizona are expected to grow by as greatly reduced. Some housing, ranch Human activity, most notably in the much as 71 percent in the next 15 years, facilities, roadways, and utilities will past century, has dramatically altered creating rural-urban edge effects across undoubtedly be constructed with the landscape of the Arizona-Sonora thousands of acres of pygmy-owl habitat changing ranch plans, and this may border, affecting both the quantity and (AIDTT 2000, p. 10; BLM files-Lands affect individual pygmy-owl territories. quality of its ecological resources. Livability Initiative). In another However, the overall impact to pygmy- Urbanization not only reduces the projection, the Arizona population is owl habitat from current rates of amount of open space, but impacts the expected to more than double within urbanization in Texas is much less than biological value of areas (Walker and the next 20 years, compared to the 2000 that in Arizona and parts of Mexico. Pavlakovich-Kochi 2003, p. 3). The population estimate (U.S. Census In Mexico, the greatest increases in Sonoran border population has been Bureau 2005, p. 1). Many cities and population have occurred mostly in increasing faster than that State’s towns within the historical distribution coastal resort areas, State capitals, and average and faster than Arizona’s border of the pygmy-owl in Arizona already along the United States-Mexico border. population; between 1990 and 2000, the experienced substantial growth during In the Sonoran Desert Ecoregion of population in the Sonoran border the 8-year time span from 2000 to 2008: Mexico (a relatively homogeneous municipios increased by 33.4 percent, Town of Carefree (30.5 percent); Casa ecological area defined by similarity of compared to Sonora’s average (21.6 Grande (56 percent); Town of Cave climate, landform, soil, potential natural percent) and the average increase of Creek (44.2 percent); City of Eloy (22.3 vegetation, hydrology, or other Arizona’s border counties (27.8 percent); City of Florence (20.3 percent); ecologically relevant variables), the percent). Urbanization has increased City of Mammoth (45 percent); Town of human population nearly doubled habitat conversion and fragmentation, Marana (139.9 percent); Town of Oro between 1970 and 1990, to a total which, along with immigration, Valley (32.5 percent); and the Town of population of 6.9 million (Gorenflo population growth, and resource Sahuarita (507.3 percent) (U.S. Census 2002, p. 13). The Sonoran capital, consumption, were ranked as the Bureau 2008, pp. 1–4). Hermosillo, grew by 116 percent. When highest threats to the Sonoran Desert This population growth has spurred a considering urban growth within Ecoregion (Nabhan and Holdsworth significant increase in urbanization and individual biotic communities, the 1998, p. 1). development in these areas. Regional human population more than doubled Urbanization has also affected pygmy- development is predicted to be high in in three of the seven major owl habitat in other parts of Mexico. certain areas within the distribution of biogeographic communities of Mexico Trejo and Dirzo (2000, p. 133) indicate the pygmy-owl in Arizona. In particular, (Arizona Upland and Lower Colorado that areas of dry subtropical forests, a wide area from the international River Valley, Plains of Sonora, and important habitat for pygmy-owls in border in Nogales, through Tucson, Magdalena Plain) (Gorenflo 2002, p. 28), southwestern Mexico, have been used Phoenix, and north into Yavapai County all of which provide important pygmy- by humans through time for settlement (called the Sun Corridor ‘‘Megapolitan’’ owl habitat. and various other activities. The long- Area) is predicted to have 8 million The United States-Mexico border term impact of this settlement has people by 2030, an 82.5 percent increase region has a distinct demographic converted these dry subtropical forests from 2000 (Gammage et al. 2008, pp. 15, pattern of permanent and temporary into shrublands and savannas lacking 22–23). If build-out occurs as expected, development related to warehouses, large trees, columnar cacti, and cover it will encompass a substantial portion exports, and other border-related and prey diversity that are important of the current and historical distribution activities, and patterns of population pygmy-owl habitat elements Trejo and of the pygmy-owl in Arizona. growth in this area of northern Mexico Dirzo (2000, p. 134) state that in Mexico Development pressure across Arizona have been accelerated relative to other dry tropical forest is the major type of has slowed due to the recent economic Mexican States (Pineiro 2001, pp. 1–2). tropical vegetation in the country,

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covering over 60 percent of the total 2007, pp. 6–7; Abbate et al. 1999, p. 54). compared to Sonora. The Sinaloan area of tropical vegetation. According to Nest success and juvenile survival were population grew at a rate of 0.9 percent official governmental maps, about 8 lower at pygmy-owl nest sites closer to over the last decade. The population in percent (approximately 160,000 square large roadways, suggesting that habitat Nayarit grew at a rate of 1.8 percent over km (61,776 square mi)) of this forest quality may be reduced in those areas the last decade. The Jalisco population remained intact by the late 1970s, and (Flesch and Steidl 2007, pp. 6–7). grew by 1.6 percent per year during an assessment made at the beginning of Currently, most roadways in Sonora 2000–2010. Colima, one of the smallest the present decade suggested that 30 are relatively narrow. However, the States in Mexico, has a total population percent of these tropical forests have Sonoran government is starting to of approximately 650,500 and grew been altered and converted to implement plans to build new highways annually at a rate of 1.9 percent over the agricultural lands and cattle grasslands. and other infrastructure improvements. last decade. These areas of Mexico are The remaining forests are restricted to Governor Bours of Sonora formed the not experiencing the high growth rates steep slopes where it is not likely that Sonoran Strategic Projects Operator, in of Sonora, and likely will not have the land will be cleared for additional conjunction with other investors, to concurrent spread of urbanization in the agricultural or development purposes carry out the construction of highway foreseeable future. In addition, most of (Allnutt 2001, p.3). However, the improvements (Wild Sonora 2009, p. 2). the growth is taking place in the large information about the current actual Of specific concern related to pygmy- cities, and not the rural areas of these extension and condition of dry tropical owl impacts is the recent improvement countries (http:www.citypopulation.de/ forests in Mexico is unclear due to of the road between Saric, in the upper Mexico-Cities.html). Also, some of the confusion in their classification and Rio Altar valley, and Sasabe, in the large cities of the southern Mexican difficulty using remote sensing to heart of the distribution of the pygmy- States, such as Guadalajara in Jalisco delineate intact dry forest (Allnutt 2001, owl in northern Sonora. Instead of just and Morelia in Michoaca´n, are not p. 3). The best available information paving the existing Altar/Sasabe road, a within the range of the pygmy-owl, so indicates that there are still expanses of new highway was constructed resulting their growth would not be affecting dry tropical forest along the Pacific in an increase of habitat impacts and pygmy-owl habitat. The rural areas coast in Mexico, including some areas fragmentation (Wild Sonora 2009, p. 2). likely contain the remaining habitat for below 1,200 m (4,000 ft) where pygmy- Another development project proposed the pygmy-owl. It is reasonable to owls are found, but there has been loss for northern Sonora is the Quitovac assume that slow or stagnant population of this forest type throughout Mexico. toxic waste dump south of Organ Pipe growth will result in fewer The actual effects of urbanization on Cactus National Monument that could developments and infrastructure biodiversity are many and mutually accept up to 45,000 tons of toxic waste projects, such as new highways, or reinforcing, including the aggravation of per year (Wild Sonora 2009, p. 7). The destruction and fragmentation of habitat the ‘‘urban heat island effect’’; the proposed site for this project is located on a landscape scale. The impacts channelization or disruption of riverine in the vicinity of a rare spring in this associated with urbanization are, corridors; the proliferation of exotic very arid region that supports pygmy- therefore, much reduced and less severe species; the killing of wildlife by owl habitat. There are documented in this portion of the pygmy-owl’s automobiles, toxins, and pets; and the pygmy-owls nesting at Quitovac (Flesch range. While the magnitude of the fragmentation of remaining patches of 2003, pp. 40–41). While this project is impacts associated with urbanization natural vegetation into smaller and currently on hold, it represents the are significant in Arizona and northern smaller pieces that are unable to support potential for impacts to pygmy-owls Mexico, we would expect these impacts viable populations of native plants or related to development and to be much reduced in the remaining 73 (Ewing and Kostyack 2005, pp. urbanization in Sonora. percent of the pygmy-owl’s range in 1–2; Nabhan and Holdsworth 1998, p. Significant human population Mexico and we expect these impacts to 2). Human-related mortality (e.g., expansion and urbanization in the remain less significant in this part of its shooting, collisions, and predation by Sierra Madre foothill corridor may range into the foreseeable future because pets) increases as urbanization increases represent a long-term risk to pygmy- of the difference in population growth. (Banks 1979, pp. 1–2; Churcher and owls in northeastern Mexico. In Texas, Lawton 1987, p. 439). The above the pygmy-owl occurred in good Nonnative Invasive Species statements, while general in their numbers until approximately 90 percent The invasion of nonnative vegetation, nature, point out the vulnerability of of the mesquite-ebony woodlands of the particularly nonnative grasses, has habitats that support pygmy-owls and Rio Grande delta were cleared in 1910– altered the natural fire regime over the the impacts that urbanization can have 1950 (Oberholser 1974, p. 452). Habitat Sonoran portion of the pygmy-owl on the extent and quality of available removal in northeastern Mexico is range. As a result, fire has become a habitat. We would expect these types of widespread and nearly complete in significant threat to the native impacts in areas that have experienced northern Tamaulipas (Hunter 1988, p. vegetation of the Sonoran Desert. Esque or are experiencing urban growth in or 8). The pygmy-owl metapopulation and Schwalbe (2002, pp. 180–190) near pygmy-owl habitats. Not all areas structure is threatened by ongoing loss discuss the effect of wildfires in the in the United States and Mexico are and fragmentation of habitat in this area. Arizona Upland and Lower Colorado experiencing this type of growth, Urbanization has the potential to River subdivisions of Sonoran especially in the southern portion of the permanently alter the last major desertscrub, which comprise the pygmy-owl’s range. landscape linkage between the pygmy- primary portions of the pygmy-owl’s Development of roadways and their owl population in Texas and those in range within Sonoran desertscrub. The contribution to habitat loss and northeastern Mexico (Tewes 1992, pp. widespread invasion of nonnative fragmentation is a particularly 28–29). annual grasses appears to be largely widespread impact of urbanization With regard to Mexico, for those areas responsible for altered fire regimes that (Nickens 1991, p. 1). Data from Arizona outside of Sonora and northeastern have been observed in these and Mexico indicate that roadways and Mexico discussed above, human communities, which are not adapted to other open areas lacking cover affect population growth in Sinaloa, Nayarit, fire (Esque and Schwalbe 2002, p. 165). pygmy-owl dispersal (Flesch and Steidl Colima, and Jalisco are relatively slow In areas comprised entirely of native

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species, ground vegetation density is Buffelgrass is most often located on 1994). By 1997, more than 1 million ha mediated by barren spaces that do not steep, rocky, south-facing slopes, with (2.5 million ac) of desertscrub and allow fire to carry across the landscape. poor soil development (Van Devender thornscrub (both communities occupied However, in areas where nonnative and Dimmitt 2006, pp. 25–26). Surveys by the pygmy-owl) had been cleared in species have become established, the completed in Sonora and Sinaloa in central Sonora to plant buffelgrass, and fine fuel load is continuous, and fire is 2006 noted buffelgrass was present in more than 2 million ha (5 million ac) capable of spreading quickly and Sonora and northern Sinaloa, but the were scheduled for future vegetation efficiently (Esque and Schwalbe 2002, p. more southerly locations were noted as conversion (Burquez and Quintana 175). Nonnative annual plants prevalent sparse or moderate (Van Devender and 1994, p. 23; Johnson and Navarro 1992, within the Sonoran range of the pygmy- Dimmitt 2006, p. 7). This was in p. 118), often as part of government owl include Bromus rubens and B. comparison to northerly sites in Sonora programs to support the ranching tectorum (brome grasses) and Schismus that were rated as dense with industry (Van Devender et al. 1997, p. spp. (Mediterranean grasses) (Esque and buffelgrass. As such, this nonnative 3). Researchers during this time period Schwalbe 2002, p. 165). Brassica species only significantly affects a predicted that, if not halted, this tournefortii (Sahara mustard) is an Old portion of the pygmy-owl’s range. The practice of buffelgrass planting will World forb that can cover 100 percent best available information indicates that permanently change the landscape of of the ground under certain conditions buffelgrass is not significantly affecting the Sonoran desert and deplete its (ASDM 2009, p. 1). In 2006, fires that areas in Mexico beyond Sonora, and associated biological diversity (Burquez burned thousands of acres of Sonoran northern Sinaloa. and Quintana 1994, p. 23). Also, given desertscrub in southwestern Arizona Buffelgrass is not only fire-tolerant the government subsidies to establish had Sahara mustard as the primary fuel. (unlike native Sonoran Desert plant exotic grasslands in order to maintain However, the nonnative species that is species), but is actually fire-promoting large cattle herds, and to support currently the greatest threat to (Halverson and Guertin 2003, p. 13). marginal cattle ranching, it is less likely vegetation communities in Arizona and Invasion sets in motion a grass-fire cycle that control measures will be northern Sonora, Mexico is the where nonnative grass provides the fuel implemented, and the desertscrub and perennial Pennisetum ciliare necessary to initiate and promote fire. thornscrub in Sonora will probably be (buffelgrass), which is prevalent and Nonnative grasses recover more quickly replaced in the near term by ecosystems increasing throughout much of the than native grass, tree, and cacti species with significantly lower species Sonoran range of the pygmy-owl and cause a further susceptibility to fire diversity and reduced structural (Burquez and Quintana 1994, p. 23; Van (D’Antonio and Vitousek 1992, p. 73; complexity (Burquez and Martinez- Devender and Dimmit 2006, p. 5). Schmid and Rogers 1988, p. 442). While Yrizar 1997, p. 387). Buffelgrass is an Indo-African grass a single fire in an area may or may not More recent figures indicate that this introduced to Mexico between 1940 and produce long-term reductions in plant is indeed occurring, with buffelgrass 1960 (Burquez et al. 1998, p. 25). The cover or biomass, repeated wildfires in present in more than two-thirds of distribution of this grass has been a given area, due to the establishment of Sonora, and 1.6 million ha (4 million ac) supported and promoted by nonnative grasses, are capable of having been deliberately cleared and governments on both sides of the United ecosystem type-conversion from native seeded with the species (Burquez- States-Mexico border as a resource to desertscrub to nonnative annual Montijo et al. 2002, p. 132). A 2006 increase range productivity and forage grassland, and render the area publication estimates that 1.8 million ha production. Buffelgrass is first unsuitable for pygmy-owls and other (4.5 million ac) have been converted to established by stripping away the native native wildlife due to the loss of trees buffelgrass in Sonora, and that between desertscrub and thornscrub (Franklin et and columnar cacti and reduced 1990 and 2000, there was an 82 percent al. 2006, p. 69). Following diversity of cover and prey species increase in buffelgrass coverage establishment, it fuels fires that destroy (Brooks and Esque 2002, p. 336). (Franklin et al. 2006, pp. 62, 66). Sonoran desertscrub, thornscrub, and, to Buffelgrass competes with neighboring Buffelgrass pastures have doubled in a lesser extent, tropical deciduous native species for space, water, and area in Sonora approximately every 10 forest; the disturbed areas are quickly nutrients (Halverson and Guertin 2003, years since 1973 (Franklin et al. 2006, converted to open savannas composed p. 13; Williams and Baruch 2000, pp. p. 67) and the conversion to buffelgrass entirely of buffelgrass. Buffelgrass is 128–135; D’Antonio and Vitousek 1992, is expected to continue into the now fully naturalized in most of Sonora, pp. 68–72). Buffelgrass conversion is foreseeable future. southern Arizona, and some areas in associated with increased soil erosion It is not only Sonoran desertscrub central and southern Baja and changes in nutrient dynamics and communities in Sonora and northern (Burquez-Montijo et al. 2002, p. 131), primary productivity (Abbot and Sinaloa that are impacted by the spread and now commonly spreads without McPherson 1999, p. 3). These changes of buffelgrass. Another unique human cultivation (Arriaga et al. 2004, make it more difficult for native vegetation community in this region, pp. 1509–1511; Perramond 2000, p. 131; vegetation to reestablish, even if the dry subtropical forests, are being lost Burquez et al. 1998, p. 26). conversion process or fires are and fragmented due to the planting of However, buffelgrass is adapted to discontinued (Franklin et al. 2006, p. buffelgrass in association with cattle dry, arid conditions and does not grow 69; Rogers and Steele 1980, pp. 17–18). ranching, which results in vast tracts of in areas with high rates of precipitation Within the past 15 years, the forest being removed and replaced by or high humidity, above elevations of establishment of nonnative grasslands buffelgrass (Allnut et al. 2001, pp. 3–4). 1,265 m (4,150 ft), and in areas with has been identified as the most serious Buffelgrass invasion in the United freezing temperatures. Areas that threat to the biological diversity of the States is such an urgent and significant support pygmy-owls south of Sonora Sonoran Desert (Burquez and Quintana issue that the Governor of Arizona, and and northern Sinaloa typically are 1994, p. 23). Economic subsidies from nearly all southern Arizona wetter and more humid, and the best the State of Sonora and low-interest municipalities and agencies have joined available information does not indicate loans from banks made funds available together to address the issue. The that buffelgrass is invading the southern for more widespread plantings of Governor formed the Arizona Invasive portion of the pygmy-owl’s range. buffelgrass in the 1980s (Camou-Healy Species Advisory Council in 2005, and

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the Southern Arizona Buffelgrass an important pygmy-owl habitat feature, the distribution of pygmy-owl locations Working Group developed the Southern the fact that buffelgrass fires reduce the from Flesch (2003, Figure 2), AGFD Arizona Buffelgrass Strategic Plan in number of tree-dominated patches and (2008a, p. 1), and Westland Resources 2008 (Buffelgrass Working Group 2008) the recruitment opportunities for those (2008, Figure 4), as well as the known in order to coordinate the control of native species dependent on them [such pygmy-owl locations and the buffelgrass. Because of its negative as saguaros] (Burquez and Quintana documented occurrence of buffelgrass in impacts to native ecosystems, 1994, p. 11), is significant. Franklin et Tucson, Avra Valley, Altar Valley, buffelgrass was declared a noxious weed al. (2010, p. 7) report significant Organ Pipe Cactus National Monument, by the State of Arizona in March 2005. changes in vegetation structure as a Pinal County, the Tohono O’odham It is not currently known whether these result of creating buffelgrass pastures for Nation, and Sonora and northern programs will be successful in grazing. There were 90 percent fewer Sinaloa show that there is almost 100 controlling buffelgrass invasion. trees and shrubs of the size used by The impacts of buffelgrass pygmy-owls (2 to 5 m (6 to 15 ft) tall) percent overlap in the areas occupied by establishment and invasion are in buffelgrass pastures as compared to pygmy-owls and the areas under substantial for the pygmy-owl in the native vegetation communities. Loss of greatest threat from buffelgrass invasion. United States and Sonora because diversity and availability of prey species One of the principle reasons that conversion results in the loss of all due to conversion are also detrimental nonnative plants pose such a significant important habitat elements, particularly (Franklin et al. 2006, p. 69; Avila negative impact on the pygmy-owl in its columnar cacti and trees that provide Jimenez 2004, p. 18; Burquez-Montijo et northern range, and the native plant nest sites. Buffelgrass invasion and the al. 2002, pp. 130, 135). communities on which they depend, is subsequent fires eliminate most Some information we received from because few, if any, reasonable methods columnar cacti, trees, and shrubs of the the public downplays the significance of currently exist to control the ongoing desert (Burquez-Montijo et al. 2002, p. the conversion of Sonoran desertscrub invasion of these plants or to remediate 138). This elimination of trees, shrubs, to buffelgrass savannas on pygmy-owl areas where they are already and columnar cacti from these areas is habitat by stating that there is no established. Mechanical removal, a significant negative impact and indication that the conversion is herbicides, and fire have all been tested potentially a threat to the survival of the occurring in areas occupied by the for their effectiveness in control of this pygmy-owl in the northern portion of its pygmy-owl (Johnson and Carothers nonnative grass. However, none have range, as these vegetation components 2003, pp. 6–7). However, when proven effective at the scale of the are necessary for roosting, nesting, compared to the maps of current and current invasion. protection from predators, and thermal predicted buffelgrass invasion in Sonora regulation. Because tree canopy cover is found in Arriaga et al. (2003, Figure 1), BILLING CODE 4310–55–P

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BILLING CODE 4310–55–C species can cause other effects to species diversity and altering the In Texas and other portions of the pygmy-owl habitat elements. For vegetative structure of the community pygmy-owl’s range in the United States, example, in Texas, studies indicate that (Davis 2011, p. 4). It is not known if such as semi-desert grasslands, invasive the spread and prevalence of the these changes in plant community species and fire are not as significant in nonnative grass, Bothriochloa structure affect pygmy-owls. their impact because the vegetation ischaemum (King Ranch bluestem), The best available scientific and communities in these areas are adapted results in this grass dominating native commercial information, as presented in to periodic fire. However, while fire grasses, forbs, and endemic species, the discussion above, leads us to may not be a primary issue, nonnative thus decreasing plant and conclude that conversion of Sonoran

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desertscrub to nonnative plant pastures native vegetation communities once introductions as well. Seed sources of composed of buffelgrass, and the agricultural activities cease. Wood native plants in these old agricultural subsequent change in the fire regime, harvesting has a direct effect on the fields are now rare. Natural regeneration has resulted in the loss of large areas of amount of available cover and nest sites of many of the old agricultural fields is pygmy-owl habitat in the northern range for pygmy-owls and is often associated unlikely because they are no longer near of the pygmy-owl, is negatively with agricultural development. Wood to a native seed source (Jackson and impacting the remaining areas of harvesting also occurs to supply Comus 1999, pp. 243–247, 250). pygmy-owl habitat in the Sonoran firewood and charcoal, and to provide It is not known to what extent the loss desert and tropical thornscrub/dry material for cultural and decorative of certain pollinators, predators, deciduous forest communities of wood carvings. While we do not have detritivores (organisms that obtain Arizona, Sonora, and northern Sinaloa, detailed information regarding the nutrients by consuming decomposing and is expected to continue to do so in impacts of agricultural development and organic matter), cryptogamic crusts (soil the foreseeable future. Other areas in wood harvesting for all areas within the with crusts formed by an association of Texas and the United States, such as range of the pygmy-owl, the following algae, mosses, and fungi; such crusts semidesert grassland, are not as affected provides a discussion of the extent of stabilize desert soil, retain moisture, and by buffelgrass and subsequent changes the impacts from these activities for protect germinating seeds), mycorrhizae in fire behavior, but may be invaded by areas for which we do have sufficient (a fungus that grows in a symbiotic other nonnative species. However, the information. association with plant roots), etc., as effect, if any, on pygmy-owls, has not The extent of agricultural well as the addition of exotic species, been studied. development and woodcutting as a will have on recovery of habitat. In contrast to the severity of current or ongoing impact to pygmy-owl Because of these profound changes, we buffelgrass invasion as a significant habitat differs between the United States believe that habitat recovery, either by negative impact to the pygmy-owl in the and Mexico. For example, in the United natural succession or through various northern portions of its range, it appears States, habitat loss and conversion due attempts at ecological restoration, will to have less impact or no impact at all to agricultural development is more of be very limited (Jackson and Comus further south. The area in Mexico that a historical issue because less area is 1999, p. 250). The significance of this is susceptible to buffelgrass invasion being used currently for agriculture, and lies in the fact that many acres of and planting represents only just over wood cutting is primarily for personal, pygmy-owl habitat have been lost to 22 percent of the pygmy-owl’s range. rather than commercial use. However, agricultural development, especially The magnitude of the impact diminishes impacts to pygmy-owl habitat from along valley bottoms and drainages that in the southern portion of the range historical agricultural use and wood were important for pygmy-owls as they where buffelgrass has not been reported harvesting are still evident. The supported higher quality meso- and in the dry tropical forests, which vegetation and soils of many valleys in xero-riparian habitats. A well-known comprise the majority of pygmy-owl the Sonoran Desert were shaped by the example of this is the huge mesquite habitat in the southern portion of its periodic flooding of dynamic wash bosque (woodland) south of Tucson on range. In addition, buffelgrass is not systems, which partially recharged a the San Xavier District of the Tohono likely to invade and persist in these shallow, fluctuating groundwater table. O’odham Nation that comprised old- areas in the foreseeable future because Because of agricultural development, growth mesquites supporting cavities it is adapted to dry, arid savannahs and these valleys no longer experience these for pygmy-owl nests, adequate cover, grasslands in its native Africa (Burquez defining processes and there has been a and prey diversity, and which was lost et al. 1998, p. 25). The elevational permanent loss of meso- and xero- due to groundwater pumping and conditions, canopy coverage, and riparian habitat (Jackson and Comus diversion for agriculture and urban precipitation patterns of the dry tropical 1999, pp. 233, 249). These riparian growth (Stromberg 1993, pp. 117–119). forest communities are not as suitable habitats are important pygmy-owl Mesquite bosques provide important for the establishment of buffelgrass as habitat, especially within drier upland pygmy-owl habitat. The viability of the arid desert and semi-desert vegetation communities like Sonoran these bosques is dependent upon the vegetation communities (Arriaga et al. desertscrub and semi-desert grasslands. ability of native trees, like mesquite, to 2004, pp. 1508–1510.). The best In Arizona, although new agricultural reach the water table with their taproots. available scientific and commercial development is limited and is expected Only then can they grow to sizes that information suggests that buffelgrass to remain limited in the foreseeable provide habitat for pygmy-owls. Even invasion should not be an issue in the future, the effects to historical habitat when abandoned and left to return to southern portions of the pygmy-owls are still evident. Jackson and Comus their natural state, there has been such range, nor should it become an issue in (1999, pp. 249–250) describe the long- extensive alteration of soils, drainage the future. term effects of agricultural development patterns, and contamination that these on native vegetation communities, ‘‘The impacted bosques are unlikely to ever Agricultural Production and Wood groundwater has been mined, river regain the historical habitat values. Harvesting flows have been relocated, tributaries Restoration of old agricultural areas Agricultural development and wood have been channelized, and smaller often meets with either limited success harvesting can result in substantial waterways are blocked by roads or the or failure. impacts to the availability and canals of the Central Arizona Project. Historically, agriculture in Sonora, connectivity of pygmy-owl habitat. Soil-surface characteristics have been Mexico, was restricted to small areas Conversion of native vegetation greatly altered by field leveling and with shallow water tables, but it had, communities to agricultural fields or irrigation ditches. Compounding these nonetheless, seriously affected riparian pastures for grazing has occurred within large-scale changes, soil in some areas habitats by the end of the nineteenth historical pygmy-owl habitat in both the has increased salinity, pesticide century. Large-scale agriculture was United States and Mexico, and not only residues, or loss of physical structure introduced in the 1940s, with the removes existing pygmy-owl habitat due to repeated tillage, soil compaction, construction of dams in the Rio Yaqui elements, but also can affect the long- and irrigation.’’ There have been and Rio Mayo watersheds. By the late term ability of these areas to return to important biological losses and 1970s, the delta regions and alluvial

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plains of these rivers were almost and may be declining in large parts of habitat can be significant due to the loss entirely converted to field crops. Huge its southern range (AQUASTAT 2007, p. of nest structures, predator and thermal expanses of natural vegetation had been 2). cover, and prey habitat. For example, in cleared. The vast mesquite forests of the Agricultural development is declining Texas, two prescribed burns over the Llanos de San Juan Bautista in the in some parts of the pygmy-owl’s range, past 3 years have consumed 1,200 to plains of the Rio Sonora disappeared but seems concentrated in the northern 1,600 ha (3,000 to 4,000 ac) respectively, with the development of the Costa De portion of the range. In certain localities including areas that supported natural Hermosillo irrigation district. In the Rio in northwestern Mexico, especially pygmy-owl nests, as well as pygmy-owl Mayo and Rio Yaqui coastal plains, Sonora, it has remained the same and nest boxes (Proudfoot 2011b, p. 1). nearly one million ha (2.5 million ac) of even increased over the past few Other documented fires on the King mesquite, cottonwood, and willow decades. In the Sonoyta Valley of Ranch consumed from several hundred riparian forests and coastal thornscrub Sonora flanking Organ Pipe Cactus up to 3,200 ha (8,000 ac) over this same disappeared after dams upriver started National Monument across the United time period (Caller 2009, NOAA 2011, to operate (Burquez and Martinez-Yrizar States-Mexico border, cropland Texas-Fire.com 2011, Firerescue 2008). 2007, p. 543). In 1980, a national food quadrupled in extent between 1977 and While the loss of woodlands to fire is system was initiated and the total area 1987, due in part to government- often a temporary impact, it can take under cultivation in northern Mexico supported agricultural development. many years for trees to reach adequate increased significantly (Stoleson et al. Proximity to U.S. fruit and vegetable size to once again support cavities used 2005, p. 59). markets, inexpensive labor, good quality for nesting by pygmy-owls. water, and government agency interest Based upon the amount of area Mesquite harvesting also has negative in increased fruit and vegetable crops in currently in irrigated agriculture, impacts on pygmy-owl habitat. the area mean that agricultural Sonora, with 530,000 ha (1.3 million Mesquite wood is a valuable production and the associated descent ac), ranks second among the States in commodity. Historically in Arizona, of groundwater levels will likely Mexico to Sinaloa (747,800 ha (1.85 mesquite trees have been harvested for continue in the future (Nabhan and million ac)), a State which is also decades. In the late 1800s through the Holdsworth 1998, p. 36). Some occupied by pygmy-owls. The area early 1900s, Arizona saw large-scale scientists surveyed noted that clearing equipped for agricultural irrigation in harvesting for fuel and for mining. for agriculture was becoming more Sonora is 668,900 ha (1.65 million ac), Fuelwood cutting once had a major severe in portions of the Lower impact on the riparian forests, mesquite resulting in the potential future loss of Colorado River Valley, Central Gulf thickets, and evergreen woodlands near approximately 139,000 ha (343,000 ac) Coast, and Viscaino. Current Sonoran most of southeastern Arizona’s major of natural vegetation communities Desert cropland is most extensive in the cities and mining centers (Bahre 1991, (AQUASTAT 2007, p. 2) if these areas border municipality of Mexicali and the p. 143). This whole-scale harvest may are developed for agriculture. Other extreme southern end of the Sonoran explain the scarcity of riparian trees in Mexican States within the range of the Desert where most municipalities have early (1890) photographs of southern pygmy-owl show similar potential for from one-quarter to three quarters of rivers such as the San Pedro (Stromberg habitat loss. For example, in their land surface as cropland. The 1993, p. 119). In the Sonoran Desert of Tamaulipas, area under irrigation central section around Hermosillo, Mexico, the mesquite tree is being increased from 174,400 to 494,472 ha Sonora, is 15 to 25 percent cropland, (431,000 to 1.22 million ac) between and the rest of the area is less than 15 harvested in order to fulfill the demand 1998 and 2004, with an area of 668,872 percent (Nabhan and Holdsworth 1998, for mesquite charcoal, and former ha (1.65 million ac) equipped for p. 36). However, these figures do not mesquite forests have disappeared at an irrigation. Michoaca´n supports 24,900 include the millions of hectares (acres) alarming rate (Burquez and Martinez ha (61,500 ac) of irrigated lands with a of abandoned agricultural land. While Yrizar 2007, p. 545). Ironwood trees are potential infrastructure for 222,800 not all the area converted for agriculture also being harvested in Mexico where additional ha (550,600 ac). Although the was or could be suitable pygmy-owl the wood is cherished for its hardness amount of land converted to agriculture habitat, agricultural development has and carving potential for native artwork seems to be on the increase, we do not typically occurred along river bottoms by groups such as the Seri Indians. know where these areas are in relation and other drainages that support Mesquite and ironwood woodlands to pygmy-owl habitat. Dry tropical important riparian habitat for pygmy- provide pygmy-owl habitat elements forests on steeper slopes are not likely owls (Flores-Villela and Fernandez related to tree canopy cover and a to be used for agricultural production. 1989, p. 2). Additionally, associated diverse prey base. Unfortunately, In addition, agricultural development in habitat fragmentation exacerbates the woodcutters and charcoal makers do not the States of Colima, Jalisco, Nayarit, actual impacts to available pygmy-owl use scrubby-type mesquite, but rather and Nuevo Leon had substantial habitat through loss of habitat take advantage of large, mature mesquite decreases in the amount of irrigated connectivity (Stoleson et al. 2005, p. 60; and ironwood trees growing in riparian lands over the same period. Colima Saunders et al. 1991, pp. 23–24). areas (Taylor 2006, p. 12), the exact tree dropped from 64,100 ha (158,394 ac) to Prescribed burning to reduce class that is of most value as pygmy-owl 37,800 ha (93,406 ac), Jalisco went from mesquite invasion into rangelands habitat. From the time ‘‘mesquite 161,600 ha (399,322 ac) to 95,600 ha represents another potential threat to charcoal’’ became popular in U.S. (236,233 ac), Nayarit decreased from pygmy-owl habitat associated with restaurants in the early 1980s, both 55,400 ha (136,896 ac) to 43,200 ha agriculture. In general, improved mesquite and ironwood have been (106,749 ac), and Nuevo Leon dropped grassland health adjacent to pygmy-owl harvested from the same lands, with as from 143,000 ha (353,361 ac) to 32,484 habitat should benefit pygmy-owls much as 15 to 40 percent of each ha (80,270 ac). These numbers indicate through improved hydrology and mesquite charcoal bag consisting of that continuing destruction of habitat enhance prey habitat. However, if ironwood prior to 1991. As a result, for agricultural production is not woodlands providing important pygmy- both trees were locally overexploited in occurring with the same intensity owl habitat are not protected during Sonora and Baja California Sur (Taylor throughout the range of the pygmy-owl, prescribed burns, impacts to pygmy-owl 2006, p. 12).

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Sonora supports 1,888,000 ha harvest (Suzan et al. 1999, p. 1499). habitat, both meso- and xero-riparian, (4,665,000 ac), or 46 percent of total Organ Pipe Cactus National Monument are crucial for maintaining viable mesquite woodlands in Mexico; more is one of four areas in Arizona that has pygmy-owl populations in the arid than double that of any other State in been consistently occupied by pygmy- portions of their range in Arizona and Mexico. This also means that much of owls. In the arid environment of the Sonora, Mexico. Loss of leguminous the mesquite harvested in Mexico comes Monument, tree canopy and structure trees results in long-term effects to the from Sonora (Taylor 2006, p. 12). are particularly important pygmy-owl soil as they add organic matter, fix Current estimates suggest that ironwood habitat features. nitrogen, and add sulfur and soluble is being rapidly depleted across an area Mesquite used as fuelwood is a salts, affecting overall habitat quality roughly equivalent to twice the size of thriving cross-border trade, although not and quantity (Rodriguez Franco and Massachusetts. In northern Mexico, over on the same scale as charcoal. However, Aguirre 1996, p. 6–47). Ironwood and 202,000 ha (500,000 ac) of mesquite local impacts can be significant in the mesquite trees are important nurse have been cleared to meet the growing areas where the fuelwood is harvested. species for saguaros, the primary nesting demand for mesquite charcoal (Haller For example, Mexican trucks loaded substrate for pygmy-owls in the 1994, p. 1). Haller (1994, p. 3) predicted with mesquite cross the border to northern portion of their range (Burquez that, if this trend continued, the entire Arizona at Sasabe. Interviews with these and Quintana 1994, p. 11). Demand for ecosystem of the Sonoran Desert could truck drivers indicated that most of the mesquite charcoal and firewood crumble, and used the examples of the wood they haul comes from ejidos contributes to the loss of extensive, degraded ecosystem along the coast of (communally owned lands) within a 20- mature mesquite forests in riparian Sonora near Kino Bay where most of the km (12.4-mi) radius of the Town of areas of northern Mexico. mesquite and ironwood had already Sasabe, an area occupied by nesting The harvest of mature mesquites in been removed and virtually all plant pygmy-owls (Taylor 2006, p. 5; Flesch the Sonoran Desert for charcoal and and animal life has disappeared. 2008, p. 2). firewood permanently alters desert Declining tree populations in the In 2008, during field work in Sonora ecosystems because leguminous trees Sonoran Desert as a result of to gather pygmy-owl genetic samples, like mesquite and ironwoods are such commercial uses and land conversion large areas of charcoal production were important anchors for these systems and threatens other plant species, and may observed near Hermosillo. Impacts to their associated flora and fauna (Taylor alter the structure and composition of vegetation were not limited to just the 2006, p. 8). Thus, ongoing wood the vertebrate and invertebrate removal of the trees, but a significant harvesting can reduce or eliminate communities as well (Bestelmeyer and area around the production sites was pygmy-owl habitat in the Sonoran Schooley 1999, p. 644). This has covered with fine, black charcoal dust Desert region of Arizona and Mexico by implications for pygmy-owl prey covering all native vegetation (Service perpetuating scrubby trees that are availability because pygmy-owls rely on 2009, p. 1). The effects of these unsuitable for nest substrates, a seasonal diversity of vertebrate and production areas are verified by reports supporting increased fire frequency invertebrate prey species; loss of tree of the complete removal of a dense associated with nonnative grass structure and diversity reduces prey mesquite bosque to the axe and charcoal invasion, eliminating important nurse diversity and availability. pits just east of Hermosillo (Taylor 2006, trees for saguaro protection, reducing In the Sonoyta region of Sonora, an p. 5). The immediate area around tall canopy coverage important for area occupied by pygmy-owls, more charcoal pits is often treeless. Walking pygmy-owl cover, and altering prey than 193,000 ha (478,000 ac) have been transects away from charcoal pits availability through the reduction of affected by deforestation related to revealed that all trees within a 1-km structural diversity. charcoal production, brick foundries, (0.6-mi) radius bear the scars of the Once common in areas of the Rio tourist crafts, and pasture conversion chainsaw (Taylor 2006, p. 7). Grande delta, significant habitat loss (Nabhan and Suzan 1994, p. 64). The Native woodlands in Sonora are and fragmentation due to woodcutting accelerated rate of legume tree (trees additionally threatened as ranchers and have now caused the pygmy-owl to be belonging to the family Leguminosae charcoal producers team up to first clear a rare occurrence in this area of Texas. whose characteristic fruit is a seed pod, the land of native trees for planting Oberholser (1974, p. 452) concluded including the mesquite and ironwood) buffelgrass, and then use the dead trees that agricultural expansion and depletion for charcoal and carvings in to produce charcoal (Taylor 2006, pp. 6– subsequent loss of native woodland and the Mexican States of Sonora and Baja 7). The end result is the incentive to thornscrub habitat, begun in the 1920’s, California has clearly affected the health clear more native woodlands. preceded the rapid demise of pygmy- of ironwood populations and associated Professional woodcutters are only owl populations in the Lower Rio plant communities (Suzan et al. 1997, p. permitted to harvest dead wood. Grande Valley of southern Texas. 955). This is evidenced by an increased However, dead wood to meet export Because much of the suitable pygmy- number of damaged and dying trees, as demands is hard to come by. A simple owl habitat in Texas occurs on private well as generally small size classes for solution practiced by many wood ranches, habitat areas are subject to sampled areas (Suzan et al. 1997, pp. cutters is to ring trees and let them die; potential impacts that are associated 950–955). then the dead wood can be legally with ongoing ranch activities such as Pressure for fuelwood and crafts harvested (Taylor 2006, p. 7). grazing, herd management, fencing, materials has been so intense in Mexico Impacts to pygmy-owl habitat in pasture improvements, construction of south of Organ Pipe Cactus National northwestern Mexico from these cattle pens and waters, road Monument that wood harvest, activities are resulting in the loss and construction, and development of especially ironwood, has been detected fragmentation of habitat in this part of hunting facilities. Brush clearing, in more than 500 m (1600 ft) into the Mexico, and the inability to recover or particular, has been identified as a Monument as supplies have been restore habitats and habitat connectivity potential factor in present and future depleted south of the border (Suzan et in Arizona. Impacts related to surface- declines in the pygmy-owl population al. 1999, p. 1499). The structure of both and groundwater loss and channel in Texas (Oberholser 1974, p. 452). wash and upland habitats in the diversions are long-term and are However, relatively speaking, the Monument have been affected by this particularly significant as riparian current loss of habitat is much reduced

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in comparison to the historic loss of development has caused the loss and the last few centuries from being habitat in Texas. Conversely, ranch alteration of a considerable area of relatively confined and intensive to practices that enhance or increase pygmy-owl habitat in Arizona, Sonora, being extensive and intensive. In the pygmy-owl habitat to support Texas, and northeastern Mexico. Past 19th century, repeated Apache raids on ecotourism can contribute to impacts continue to affect the extent of ranchers and the paucity of water conservation of the pygmy-owl in Texas available pygmy-owl habitat in these limited cattle production to relatively (Wauer et al. 1993, p. 1076). The best areas, because of the extended time it small areas (Bahre 1991, pp. 114–115). available information does not indicate takes for these lands to recover, even if However, the late 19th century saw the that current ranching practices are negative actions cease, and impacts are largest stocking rates in history; significantly affecting pygmy-owl expected to continue in many of these extensive cattle production played a habitat in Texas. same areas into the foreseeable future. major role in the transformation of Tamaulipan brushland is a unique However, based on our review of the grasslands to scrublands, down-cutting ecosystem that is found only in the best available scientific and commercial of arroyos, the spread of nonnative Lower Rio Grande Valley of south Texas information, we conclude that these plants, and degradation of riparian and northeastern Mexico. This impacts are limited in magnitude, areas. Stocking rates are now much vegetation community has historically because they are significant only in the lower than in the 1890s because supported occupancy by pygmy-owls. northern portion of the range (Arizona, regulations such as those of the Taylor Brush clearing, pesticide use, and Texas, northwestern and northeastern Grazing Act of 1934 helped improve irrigation practices associated with Mexico). Moreover, the best available rangeland quality in the United States. agriculture have had detrimental effects scientific and commercial data indicate However, overstocking still continues in on the Lower Rio Grande Valley that habitat loss due to woodcutting or parts of northwestern Mexico, and (Jahrsdoerfer and Leslie 1988, p. 1). agriculture is primarily historical in Mexico’s COTECOCA (Comisio´n Since the 1920’s, more than 95 percent Texas, and these activities are not Te´cnico Consultiva de Coeficientes de of the original native brushland in the currently impacting habitats occupied Agostadero) statistics confirm that 2 to Lower Rio Grande Valley has been by pygmy-owls on the private ranches 5 times the recommended stocking rates converted to agriculture or urban use. in Texas. Further, the impacts in the occur with regularity on the Sonoran Along the Rio Grande River below southern portion of the range are less side of the border (Walker and Falcon Dam, 99 percent of the land has extensive, both because woodcutting Pavlakovich Kochi 2003, p. 14; Nabhan been cleared for agriculture and and agricultural development appear to and Holdsworth 1998, p. 2). development. Cook et al. (2001, p. 3) have less impact in the southern portion Available information on livestock indicated that both banks of the Rio of the pygmy-owl’s range, and because grazing in Mexico that we evaluated was Grande are now completely developed the pygmy-owl seems to be common focused primarily on the border areas with homes or farms, and that the only throughout this area. Therefore, after adjacent to the United States and in the remaining natural habitat areas south of reviewing and evaluating the best arid areas of northwestern Mexico, such the river are salt marshes and mudflats, available scientific and commercial as Sonora. In Sonora, rangelands are both communities that are not used by data, we conclude that woodcutting and often heavily grazed, with effects pygmy-owls. A large percentage of agricultural development are not threats particularly apparent during drought similar habitat has been cleared in to the continued existence of the (Rorabaugh 2008, p. 25). Sonora’s higher Mexico (Jahrsdoerfer and Leslie 1988, p. pygmy-owl rangewide, and are not stocking rate is likely due to its greater 17). This is supported by Tewes’ (1992, likely to become so in the future. amounts of private and ejidal p. 29) conclusion that most of the Rio (communal) land, less regulation, and Grande delta of Texas and Mexico has Improper Livestock Grazing the greater dependence on ranching and been developed over the past 60 years. Probably no single land use has had farming in Mexico. Demand in North Hunter (1988, p. 8) states, ‘‘Habitat a greater effect on the vegetation of America drives the number of cattle in removal in Mexico is widespread and southeastern Arizona or has led to more Sonora. The number of cattle in Sonora nearly complete in northern changes in the landscape than improper nearly doubled between 1950 and 1960. Tamaulipas.’’ livestock grazing and range-management The Sonoran cattle population was Habitat fragmentation in northeastern programs (Carothers 1977, p. 4). 1,652,771 in 1990 according to official Mexico is extensive, with only about Undoubtedly, grazing since the 1870s government statistics (Hawks 2003, p. two percent of the ecoregion remaining has led to soil erosion, destruction of 5). Other authors estimate the intact, and no habitat blocks larger than those native plants most palatable to overstocking at 177 percent (Lopez 250 square km (96.5 square mi), and no livestock, changes in the regional fire 1992), with 60 to 400 percent protected areas (Cook et al. 2001, p. 4). ecology, the spread of both native and overstocking in some areas (Burquez- This has the potential to limit pygmy- alien plants, and changes in the age Montijo et al. 2002, p. 134). Excessive owl movements and dispersal, structure of evergreen woodlands and grazing of vegetation by livestock, exacerbating the effects of small, riparian forests (Bahre 1991, p. 123). especially when combined with isolated populations. Fire is often used Many areas of pygmy-owl habitat have conversion of plant cover to exotic to clear woodlands for agriculture in recovered from these historical effects of pasture grasses, ranked as number four this area of Mexico, and many of these grazing; however, other areas are slow to on a list of threats to the Sonoran Desert fires are not adequately controlled. recover and may never recover due to Ecoregion (Nabhan and Holdsworth There may be fire-related effects to the arid nature of the Sonoran Desert. 1998, p. 1). native plant communities (Cook et al. Livestock grazing in northwestern One research study showed that 2001, p. 4); however, there is no Mexico is probably the most widespread overgrazing in Sonora leaves the available information of how much area human use of Sonoran ecoregional Mexican landscape more exposed and, may be affected by this activity. landscapes. Grazing by cattle, goats, and as a result, it dries out more rapidly The best available scientific and other livestock has reduced vegetation following summer convective commercial information indicates that cover and helped change grasslands to precipitation. After about 3 days, historical land clearing, as a result of shrublands. Livestock grazing in the depletion of soil moisture evokes a wood harvesting and agricultural Sonoran Desert has fluctuated greatly in period of higher surface and air

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temperatures in northwestern Mexico Larger trees provide substrates for nest exists on the problem and there is (Bryant et al. 1990, pp. 254–258). These cavities. Structure diversity provides apparently no strategy at a national level drier soils and higher temperatures can important predator and to solve the problem. The present trends result in impacts to vegetation survival thermoregulatory cover, as well as an pose serious concerns for the future of and persistence. Effects of poorly increased number and diversity of prey Mexico’s riparian ecosystems (Deloya managed livestock grazing in Sonora species. A reduction of the extent or 1985, pp. 11–12). include changes in plant species quality of riparian habitats within the In Texas, areas occupied by pygmy- composition and vegetation cover and range of the pygmy-owl represents owls are primarily on large, private structure, soil compaction, erosion, direct impacts on the availability and ranches where livestock production is a altered fire regimes, and nonnative plant quality of pygmy-owl habitat. primary objective. However, alternative species introductions and invasions Although proper management has sources of revenue for these ranches (Stoleson et al. 2005, pp. 61–62). With greatly improved riparian communities also include hunting and ecotourism. As regard to pygmy-owl habitat, improper in some areas, field data compiled in the a result, habitat management for the stocking rates can result in reduced last decade showed that riparian areas benefit of wildlife is also a high priority saguaro reproduction through trampling throughout much of the West were in for these ranchers. Livestock and alteration of microclimates the worst condition in history due management is often conducted with (Abouhaider 1989, pp. 40–48), reduced mainly to the complications initiated by consideration of impacts to wildlife. tree cover and reproduction through improper grazing techniques (Krueper Pygmy-owls are known to exist in grazing of seedlings and seed pods, and 1993, p. 322). However, information areas that are grazed. Grazing, itself, impacts to prey availability from submitted during the public comment does not appear to negatively affect reduced vegetation structural diversity period supports the idea that, in certain pygmy-owls. Properly managed grazing and species composition. areas, riparian habitat has returned and, can enhance certain pygmy-owl habitat One of the most significant adverse perhaps, even increased in certain areas elements (Loeser et al. 2007, p. 96; impacts within western riparian systems in Arizona, including areas that are Holechek et al. 1982, p. 208). Climatic has been the perpetuation of improper being grazed by livestock. Parker (2008, variation is important in determining grazing practices. Belsky et al. (1999, p. p. 13) points out that Webb et al. (2007, the ecological effects of grazing 419) found that grazing by livestock has pp. 388–389, 404–408) conclude that, in practices in arid rangelands (Loeser et damaged 80 percent of the streams and the drainages they studied, increases in al. 2007, pp. 93–96). However, improper riparian ecosystems in the arid regions riparian vegetation from 24 percent to grazing at inappropriate stocking rates of the western United States. The initial 49 percent had occurred since the late or during seasons or years when drought deterioration of western riparian 1800s and early 1900s, and that and other conditions reduce forage systems began with the severe increases in the density of riparian availability can affect pygmy-owls overgrazing in the late nineteenth plants appear to have accelerated in the directly through the loss of important century. Livestock grazing can affect 1970s. We are encouraged by this habitat elements (e.g., saguaros, tree four general components of riparian positive information indicating that cover, riparian vegetation, vegetation systems: (1) Streamside vegetation; (2) riparian habitats in some areas may reproduction) and prey availability. No stream channel morphology; (3) shape become suitable for pygmy-owls in the studies specifically related to the effects and quality of the water column; and (4) future if grazing continues to be of livestock grazing on pygmy-owls have structure of streambank soil. Vegetation properly managed. It is not our been conducted; however, impacts to impacts include: (1) Compaction of soil, contention that grazing per se has a pygmy-owls can be determined which increases runoff and decreases negative effect on riparian areas, but indirectly from studies on related water availability to plants; (2) herbage that improper or overgrazing can have species or issues. For example, studies removal, which allows soil temperatures detrimental effects. Parker (2008, p. 14) in Arizona and Sonora show that the to rise, thereby increasing evaporation; reiterates this by stating, ‘‘While there is number of lizard species and abundance (3) physical damage to vegetation by little question that overgrazing can of lizards declined significantly in rubbing, trampling, and browsing; and degrade riparian ecosystems, the heavily grazed areas (Jones 1981, p. (4) alteration of growth form of plants by question here is whether grazing has 111); there is also a likely loss of lizard removing terminal buds and stimulating had long-term negative effects on woody species in areas invaded by buffelgrass. lateral branching (Fleischner 1994, p. riparian vegetation in Arizona.’’ We Lizards are an important food resource 635). acknowledge that, with proper for pygmy-owls; therefore, impacts to In a summary of studies investigating management, riparian areas can recover lizard abundance can affect pygmy- the impacts of livestock grazing on and provide habitat for the pygmy-owl. owls. riparian areas, Belsky et al. (1999, p. In Mexico, increasing human An additional concern related to 425) found that none of the studies population numbers and the extent of grazing lands is that, faced with rising showed positive impacts or ecological subsistence agriculture threatens the land prices, unstable markets, and benefits that could be attributed to future of Mexico’s extensive riparian unpredictable climate, many ranchers in livestock activities when grazed areas systems. Grazing impacts include the United States are choosing or are were compared to protected areas. It contamination and an increasing forced to sell their private lands to real was mostly negative effects that were demand for agricultural and forage estate developers or subdivide it reported, and there was little debate production (Deloya 1985, pp. 9–11). themselves. This results in these lands about those effects. Most of these Riparian destruction is evident being subject to the threats described studies tended to agree that improper throughout Mexico, but especially in above related to urbanization. There was livestock grazing can damage stream areas of denser human population. Of no available information to determine if and riparian ecosystems. All types of particular relevance to the pygmy-owl these same pressures apply to grazing riparian habitats provide important has been the loss and destruction of lands in Mexico. pygmy-owl habitat elements due to the virtually all of the dense woodlands Improper livestock grazing has a increased size, diversity, and structure within the Rio Grande River valley. negative impact on pygmy-owl habitat associated with riparian communities Despite the evident destruction of under some circumstances in Arizona and enhanced moisture availability. riparian systems, little information and Sonora. While we expect that

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continued implementation of improved illegal border activities (Cohn 2007, p. movements by pygmy-owls. Raptors are grazing-management techniques will 96). These activities result in direct often attracted to artificial hunting reduce grazing impacts on pygmy-owls impacts to pygmy-owl habitat. perches, especially in areas that lack tall in Arizona and Texas, we expected that Additional information from the NPS trees (Oles 2007, p. 1; Heintzelman overgrazing will continue to negatively indicates a significant issue ‘‘* * * is 2004, p. 35; Askham 1990, p. 147). impact pygmy-owls in Sonora and other the increasing drug smuggling, illegal Border fences can provide open hunting parts of northern Mexico. Within the immigrants, and law enforcement areas and improved hunting perches for Sonoran desert, over grazing can result activity which results in much greater a variety of raptors that are potential in loss of structural habitat components human disturbance of the birds.’’ predators of pygmy-owls. This important to pygmy-owls, as well as Further elaboration shows that the NPS combination of perches, open area, and reducing prey availability and diversity. believes ‘‘* * * that cactus ferruginous an impediment to movement may result Additionally, improper grazing during pygmy-owls within the Monument have in increased predation of pygmy-owls, droughts can affect the long-term been subject to repeated disturbance particularly dispersing juvenile pygmy- viability of riparian habitats, which are events and some habitat degraded as a owls. Because the overall population of an important habitat type for pygmy- result of long-term drought and impacts pygmy-owls likely functions as a owls in Arizona and Sonora. However, associated with illegal migration, drug metapopulation, the pygmy-owl there is no indication that livestock smuggling, and law enforcement depends on dispersal, emigration, and grazing precludes occupancy by pygmy- interdiction efforts’’ (Snyder 2005, pp. immigration to maintain the genetic and owls in any part of its range. While 1–3). Trails and roadways remove demographic fitness of regional improper livestock grazing can have pygmy-owl habitat features, noise and populations. To the extent that border negative impacts to local pygmy-owl disturbance from people and vehicles infrastructure and activities reduce or populations, we do not believe livestock disrupt important behaviors, and there prevent such movements, and increase grazing is significantly affecting pygmy- is an increased risk of fire in important the likelihood of pygmy-owl predation, owl populations throughout its range. habitats resulting from cooking and it follows that population-level impacts The best available scientific and warming fires, as well as signal fires may result. commercial information does not appear used by cross-border immigrants and Impacts to pygmy-owls from border to indicate that improper grazing is smugglers. Areas occupied by pygmy- infrastructure and illegal activities are affecting pygmy-owl populations in owls in Organ Pipe Cactus National likely limited to the immediate border Texas. We have no readily-available Monument have been abandoned by the areas of Arizona and northern Sonora. information to determine whether the owls, likely due, at least in part, to Information was not readily available so effects of livestock grazing on pygmy- heavy illegal immigrant traffic and that we could determine the extent of owl habitat in Mexico outside of Sonora associated enforcement actions. these impacts in Texas and northeastern are greater or more harmful than in There is fear that efforts to curb illegal Mexico, although they are likely to be Arizona and Sonora, but we suspect border activities through the similar (habitat gaps, perches for impacts are similar. Based on the best construction of infrastructure such as raptors, etc.). Nevertheless, these available scientific and commercial fences and barrier will fragment the impacts are restricted to the border data, we conclude that improper Sonoran Desert ecosystem, damage the regions of Arizona and Texas, and only livestock grazing is not a threat to the desert’s plant and animal communities, affect a relatively-small portion of the continued existence of the pygmy-owl and prevent free movement of wildlife pygmy-owl range. This localized effect rangewide, nor is it likely to become so. between the United States and Mexico reduces the magnitude of this impact to (Cohn 2007, p. 96). During the time the the overall pygmy-owl population. Border Issues pygmy-owl was listed under the Act, we Therefore, based on the best available One of the most pressing issues for consulted on the effects of Federal scientific and commercial data, we the Arizona-Sonora border is the impact border infrastructure projects and conclude that effects associated with of illegal human and vehicular traffic identified a number of potential impacts border activities are not a threat to the through these unique and (Service 2003, pp. 66–85). The continued existence of the pygmy-owl environmentally sensitive areas. Many construction of new border rangewide, and are not likely to become of these locations now bear the scars of infrastructure in the form of pedestrian so in the future. wildcat trails, abandoned refuse, and fences, vehicle barriers, and patrol roads trampled vegetation (Marris 2006, p. create impediments to pygmy-owl Off-Highway Vehicle (OHV) Use 339; Walker and Pavlakovich-Kochi movement across the border due to The information we have on impacts 2003, p. 15). Monitoring activities by the pygmy-owl flight patterns and behavior to the pygmy-owl from OHV use relates U.S. National Park Service (NPS) (Marris 2006, p. 239; Vacariu 2005, p. primarily to Arizona. Information was estimate that, annually, 300,000 354). The fences and vehicle barriers, not readily available on any potential individuals illegally cross through when considered in conjunction with OHV impacts to pygmy-owls or pygmy- Organ Pipe Cactus National Monument patrol roads, drag roads, and vegetation owl habitat in Texas and Mexico. in southwestern Arizona. Video removal, result in a combination of OHV use is widespread in Arizona surveillance equipment erected at nonvegetated area with a raised and occurs on lands under a variety of Coronado National Memorial, in structure in the middle causing an management entities including the southeastern Arizona, indicates traffic impediment to pygmy-owl movement, Forest Service, Bureau of Land volumes ranging from 100 to 150 particularly given their normal flight Management, State Land Department, immigrants per night (Walker and patterns, where normal flights are Tribes, and private individuals. The use Pavlakovich-Kochi 2003, p. 15). In the generally less than 30 m (100 ft) and of OHVs has grown considerably. For Cabeza Prieta National Wildlife Refuge, typically only 1.5 to 3.0 m (5 to 11 ft) example, as of 2007, 385,000 OHVs located in southwestern Arizona, which above the ground (Flesch and Steidl were registered in Arizona (a 350 supports resident pygmy-owls, there are 2007, p. 35; AGFD 2008b, p. 5). Flesch percent increase since 1998) and 1.7 over 640 km (400 mi) of illegal roads et al. (2009, pp. 7–9) show that the million people (29 percent of Arizona’s plus another 1,280 km (800 mi) of vegetation gaps, in association with the population) engaged in off-road activity unauthorized foot trails as a result of tall fences, may limit transboundary from 2005 to 2007 (Sacco 2007). Over

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half of OHV users reported that merely For instance, we have detailed locations of pygmy-owls in the United driving off the paved road was their information that in the Arizona and States. For example, in 1996, a resident primary activity, versus using the OHV Sonoran Desert Ecoregion, pygmy-owl in Tucson reported a pygmy-owl for the purpose of seeking a destination habitat loss and fragmentation resulting sighting (documented pair) that to hunt, fish, or hike (Sacco 2007). from urbanization, changing fire regimes subsequently was added to a local Specific impacts to the pygmy-owl or its due to the invasion of buffelgrass, birding hotline, and the location was habitat from OHV use when driving off agricultural development and added to their website on the internet. road include disturbance from noise and woodcutting, overgrazing, and border Several carloads of birders were later human activity, vegetation damage, issues have had significant negative observed in the area of the reported changes in plant abundance and species impacts on pygmy-owl habitat in these location (AGFD 1999, p. 12). As recently composition, reduced habitat areas and will likely continue to do so as 2003, property owners in Tucson connectivity, soil compaction, soil to varying degrees in the foreseeable have expressed concerns that birders erosion, reduced water infiltration, future. In Texas, which comprises and others have been documented higher soil temperatures, destruction of approximately five percent of the trying to get photos or see pygmy-owls cryptogamic soils (soil with crusts pygmy-owl’s range, historical loss of at occupied sites (AGFD 2003, p. 1). formed by an association of algae, habitat has reduced the pygmy-owl In Texas, Tewes (1992, p. 28) states, mosses, and fungi; such crusts stabilize range, but current impacts, such as ‘‘Frequent disruption by well- desert soil, retain moisture, and protect livestock grazing and the invasion of intentioned bird enthusiasts with call germinating seeds), and increased fire- nonnative plants, are reduced in their imitations may produce a local risk to starts (Boarman 2002, pp. 46–47; Ouren magnitude and severity. the pygmy-owls, especially during et al. 2007, pp. 6–7, 11, 16). For the larger part of the pygmy-owl’s breeding season.’’ We believe this Of specific concern is the regular use ranger in Mexico (the remaining 73 disturbance problem is most significant by OHV operators to utilize xero- percent south of Sonora), the best in southern Texas. Oberholser (1974, p. riparian washes as travel ways. These available data indicates that many 452) made a similar observation: ‘‘They washes provide important habitat impacts to pygmy-owl habitat are [pygmy-owls] are considerably elements for pygmy-owls due to the reduced in their magnitude and severity disturbed by hordes of bird watchers, increased structure and productivity of or absent altogether. The rate of growth some of whom keep their portable tape vegetation resulting from the presence in these southern Mexican States is recorders hot for hours at a time in of increased moisture. Pygmy-owls use relatively slow compared with growth hopes that one of these rare birds will these wash areas for foraging, dispersal, in Sonora and the Arizona border region answer.’’ Recreational disturbance of thermal and predator cover, and for and is expected to remain that way. pygmy-owls in Texas is particularly an movements within their home range. Agricultural development has decreased issue in the side patches of mesquite, Wash areas are often narrow and in these areas, and buffelgrass is not a ebony, and cane in Starr and Hidalgo constrained, resulting in OHV impacts known threat to pygmy-owl habitat in Counties (Oberholser 1974, p. 452). to vegetation and concentrated noise this area and is not expected to become Oberholser (1974, p. 452) and Hunter and disturbance, affecting the use and a threat in the future because of (1988, p. 6) suggest that recreational suitability of these areas as pygmy-owl unfavorable growth conditions for birding may disturb pygmy-owls in habitat. buffelgrass. Historical loss of pygmy-owl highly visited areas, affecting their Pygmy-owls may be affected by OHV habitat in northeastern Mexico has occurrence, behavior, and reproduction. use in riparian areas. However, this occurred, but there is no available Tewes (1992, p. 12) indicates that many effect is temporary and not continuous. evidence that significant habitat amateur and professional ornithologists Pygmy-owls may leave the area if destruction is currently taking place. In have strictly controlled or eliminated disturbed by noise and return once the addition, pygmy-owls are still their use of taped calls to locate pygmy- activity has ceased. Pygmy-owl habitat considered common in the southern owls because of the potential to affect destruction in Arizona may result from portion of their range. This information the pygmy-owl’s behavior. OHV activity, but the magnitude and indicates that the negative impacts to Currently, a number of ranches in severity of this impact is relatively pygmy-owl habitat discussed herein Texas offer the opportunity to view and minor. Based on our evaluation of the have different levels of effects on the photograph pygmy-owls. An internet best available scientific and commercial populations of pygmy-owls throughout search revealed invitations to birders to data, we conclude that OHV use does their range, and are much reduced or view pygmy-owls on the Canelo, King, not threaten the continued existence of absent in the southern portion of the and San Miguelito ranches. pygmy-owl, and is not likely to do so in pygmy-owl’s range. Based on the best Additionally, both the AGFD and the the future. available scientific and commercial Service continue to get requests to view information, we conclude that the and photograph pygmy-owls in Arizona. Summary of Factor A present or threatened destruction, Summary of Factor B In summary, pygmy-owls require modification, or curtailment of its habitat elements such as mature habitat or range is not a threat to the In summary, impacts to pygmy-owls woodlands that include appropriate pygmy-owl rangewide now or in the from over-zealous birdwatchers have cavities for nest sites, adequate foreseeable future. been documented in some areas within structural diversity and cover, and a the range of the pygmy-owl. While diverse prey base. A number of negative Factor B: Overutilization for pygmy-owls continue to be a highly impacts described in Factor A are Commercial, Recreational, Scientific, or sought after species by birders, there is affecting pygmy-owl habitat within Educational Purposes some indication that compliance with portions of its range. However, the best We are unaware of any overutilization etiquette related to use of tape-playback available scientific and commercial of pygmy-owls for commercial, or call imitation has improved. We were information indicates that most of these scientific, or educational purposes. unable to find any information on the impacts are either restricted to or are However, the pygmy-owl is highly effects of birding on pygmy-owls in greater in a smaller subset of the pygmy- sought after by birders, who concentrate Mexico, but we do not believe that it is owl’s range (approximately 27 percent). at several of the remaining known a significant issue in Mexico, except

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perhaps on local ranches or ejidos information to conclusively support this Summary of Factor C where ecotourism and bird watching are hypothesis. Predation is a significant In summary, our review of the best promoted. While the above impacts may pygmy-owl nest mortality factor available information suggests that negatively affect individual pygmy-owls associated with nest boxes and tree disease and predation clearly have the on a local basis, landowners in areas cavities in Texas. Proudfoot (2011a, p. potential to affect pygmy-owl that promote ecotourism are also likely 1) indicates that predation rates on individuals and populations, and have to implement actions that have positive natural cavities and unprotected nest done so in local populations. However, effects for the pygmy-owl. We conclude, boxes have been as high as 40 to 60 information related to these factors is based upon our review of the best percent, with an average of 25 to 30 limited to pygmy-owl populations in the commercial and scientific data percent. United States. We have only limited, available, that overutilization for Domestic cat predation of pygmy-owls anecdotal information related to commercial, recreational, scientific, or predation on pygmy-owls in Mexico. educational purposes is not a threat to has been documented in both Texas and Even in the United States, where the pygmy-owl now or likely to become Arizona (AGFD 2003, p. 1; Proudfoot predation has been documented, we so. 1996, p. 79). Human population growth can increase the numbers of subsidized conclude that it is not resulting in Factor C: Disease or Predation predators, such as household cats, that significant effects to the status of the Documentation of disease or can affect pygmy-owl populations. As pygmy-owl, because no disease or predation as a significant mortality the number of potential predators predation effects have been identified as factor within a wildlife population increases, the chance of predation on having population-level effects on requires extensive monitoring and the pygmy-owls increases. In addition, pygmy-owls. Based upon our review of ability to observe individuals in hand. domestic house cats consume the best commercial and scientific data With regard to pygmy-owls, monitoring considerable quantities of birds, available, we conclude that disease and and capture has only occurred with any reptiles, insects, and small mammals, predation are not threats to the pygmy- regularity in Arizona and Texas within reducing available pygmy-owl prey owl now or in the future. the United States. This has included the availability (Barratt 1995, p. 185; Factor D: Inadequacy of Existing capture of hundreds of individual Coleman et al. 1997, p. 2; Evans 1995, Regulatory Mechanisms pygmy-owls and subsequent monitoring p. 4). This introduction of additional Regulations that could potentially using radio telemetry. Consequently, all potential predators and a reduction in of the available information on disease address conservation of the pygmy-owl prey availability negatively affects or pygmy-owl habitat in both the United and predation is from Arizona and pygmy-owls. Texas. We are aware of only limited, States and Mexico may occur at a anecdotal information related to Ectoparasites have recently been number of different levels of predation for northwestern Mexico identified as a potential threat to government, from Federal to local. The (Flesch 2010, pers. comm.). The pygmy-owl populations (Proudfoot et al. following discussion addresses the following discussion outlines our 2005, pp. 186–187; Proudfoot et al. existing regulatory mechanisms related evaluation of the information related to 2006c, pp. 874–875). These recent to the conservation of pygmy-owls and disease and predation that we have investigations in Texas and Arizona pygmy-owl habitat based on the best available from Arizona and Texas. have indicated the regular occurrence of available information. Little is known about the rate or avian parasites in the materials inside of Although the pygmy-owl in Arizona causes of mortality in pygmy-owls; pygmy-owl nest cavities. The numbers is considered nonmigratory, it is however, they are susceptible to of parasites may be high enough to protected under the Migratory Bird predation from a wide variety of affect nestling pygmy-owl health and Treaty Act (MBTA) (16 U.S.C. 703–712). species. Recent research indicates that survival. Blood parasites have been The MBTA prohibits ‘‘take’’ of any natural predation likely plays a key role implicated in reduced body condition migratory bird; however, unlike take in pygmy-owl population dynamics, and impacts to survival and dispersal in under the Endangered Species Act, particularly after fledging and during small raptors (Dawson and Bortolotti some Federal courts have concluded the postbreeding season (AGFD 2003, p. 2000, pp. 3–5). Proudfoot et al. (2005, that the MBTA does not apply to 2). AGFD telemetry monitoring in 2002 pp. 186–187) could not rule out that indirect forms of take such as habitat indicated at least three of the nine blood loss from external parasites, in destruction, unless direct mortality or young produced that year were killed by combination with other factors, may destruction of an active nest occurs predators prior to dispersal during a have contributed to the loss of an entire during the activity that causes the year when tree species failed to leaf out clutch of pygmy-owls in Arizona. habitat destruction. Other Federal and due to drought conditions (AGFD 2003, State regulations and policies, such as p. 2). Increased predation during a The West Nile virus has been the Clean Water Act, the Department of particularly harsh drought year (2004) identified as the cause of a number of Defense’s Integrated Natural Resources in Arizona prompted a rescue effort by raptor mortalities throughout the United Management Plans (Barry M. Goldwater the AGFD and the Service during which States, including Arizona. A number of Range) (Uken 2008, p.1), National Park two hatch-year pygmy-owls were North American owl species have Service policy, the inclusion of the temporarily brought into captivity to documented mortality from West Nile pygmy-owl on the State of Arizona’s list increase their chances of survival. They virus, including the northern pygmy- of Species of Special Concern (AGFD were subsequently released when owl (Gancz et al. 2004, p. 2139). 1996, p. 15), and various municipal habitat conditions improved (Service However, the West Nile virus has not planning documents (Oro Valley 2008, 2004, p. 1). Pygmy-owl predation by been documented in cactus ferruginous p. 1) provide varying levels of screech owls has been identified as a pygmy-owls in either the United States protection, but have not been effective potential factor contributing to the or Mexico, and no pygmy-owl in protecting the pygmy-owl in Arizona decline of regional pygmy-owl mortalities have been suspected to be from further decline. As a result of the population groups (AGFD 2008b, p. 9). the result of an infection with the West implementation of the 2005 Real ID Act, However, there is not enough Nile virus. the U.S. Department of Homeland

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Security has waived application of the biologists’ inability to meet the reserves have already disappeared, Endangered Species Act and other requirements or pay the fees. This which reflects the tenuous state of many environmental laws in the construction would have a substantial negative effect nature reserves in Mexico during the of border infrastructure, including areas on our ability to conserve pygmy-owls 1990s (Burquez and Martinez-Yrizar occupied by the pygmy-owl (73 FR within Arizona. 2007, p. 546). 5271). Some local conservation The State of Texas lists the pygmy- Another program set up to promote mechanisms, such as habitat owl as threatened (TPWD 2009, p. 1). wildlife management on private conservation plans, are in development This designation requires permits for property in Mexico is the development in southern Arizona. These plans take of individuals for propagation, of wildlife management units, or UMAs. include conservation measures for zoological gardens, aquariums, The UMA program in Mexico has not pygmy-owls, but are at least a year from rehabilitation purposes, and scientific been effective in promoting wildlife completion, and as drafts, do not afford purposes (Texas Parks and Wildlife management or biodiversity the pygmy-owl any level of protection Code Chapters 67 and 68; Texas conservation. It has increased the or conservation (although some pygmy- Administrative Code Sections 65.171– introduction of exotic wildlife species to owl habitat has been conserved through 65.176, Title 31). There are no meet hunting demands. There is a lack acquisitions related to these plans). provisions for habitat protection. The of technical capability on private lands There are currently no statutory or pygmy-owl is also on the Texas to conduct proper wildlife monitoring regulatory provisions under Arizona law Organization for Endangered Species and management (Weber et al. 2006, p. addressing the destruction or alteration (TOES) ‘‘watch list,’’ but this list 1482). In Mexico, the exploitation of of pygmy-owl habitat. provides no regulatory protection for the minerals and industrial development One member of the public provided species or its habitat (TOES 1995, p. 1). has not been matched by strong information indicating that, because the The establishment of protected areas measures to protect the environment current distribution of pygmy-owls of habitat and management to enhance (Burquez and Martinez-Yrizar 2007, p. occurs primarily on lands under or restore habitat are important to the 547). Riparian management in particular Federal, State, or Tribal control, these conservation of pygmy-owl populations seems to lack sufficient efforts (Kusler lands are not at risk for the primary in both the United States and Mexico. 1985, p. 6). threats that have been identified (James In the United States, this could Summary of Factor D 2008, p. 8). However, activities occur on potentially be accomplished on lands all these lands that can result in all of managed by Federal agencies such as In summary, Federal laws such as the the negative impacts to pygmy-owls the Park Service, Bureau of Land Migratory Bird Treaty Act and Arizona identified in our 90-day finding and this Management, Department of Defense, and Texas State laws do address direct document. None of these types of lands and the Service. However, many of take of pygmy-owls within the United are immune to or restricted from these lands have a multiple-use States. Existing regulations in Mexico impacts of facilities development, mandate and do not focus solely on do not protect or conserve pygmy-owls. nonnative invasive species, changing pygmy-owl conservation, or even Laws and regulations within the range fire regimes, drought, climate change, wildlife conservation in general. Similar of the pygmy-owl in both the United wood harvesting, bird watching, avian issues exist in Mexico as well. Goals States and Mexico do not address the disease and predation, border issues, or and objectives of wildlife management loss of or impacts to pygmy-owl habitat. any of the other impacts discussed in Mexico have primarily focused on However, within the majority of the above. In fact, it is on these very lands huntable or harvestable species. range of the pygmy-owl, the inadequacy that many of these impacts, such as A Mexican program to protect of existing regulations does not appear border issues, nonnative species sensitive habitats and species is the to affect the frequency or magnitude of invasions, fire, and recreation are National Natural Protected Areas impacts to pygmy-owls and their concentrated. As discussed above, (NPAs) system. NPA designation is habitat. Therefore, based on the best existing regulations governing these supposed to protect areas that have not scientific and commercial information lands do not specifically protect pygmy- been significantly altered by human available, we find that, despite the lack owls or their habitats, particularly activities and that provide diverse of specific laws or regulations absent protection under the Act. ecosystem services. However, prior to addressing impacts to and conservation A potential regulatory effect not 1994, most NPAs lacked sound and and protection of pygmy-owls and their specifically related to protection of the comprehensive management plans. By habitat, the inadequacy of regulatory pygmy-owl, but which will affect our 2000, approximately 30 percent of new mechanisms does not threaten the ability to conserve the pygmy-owl, has and existing NPAs had developed pygmy-owl rangewide, and is not likely recently come to light with regard to management plans. However, under the to do so in the future. Arizona State Trust lands. The Arizona NPA model, these plans lacked detailed State Land Department is considering information, and in many cases could be Factor E: Other Natural or Man-Made restricting access to State Trust Lands considered obsolete. NPA goals to Factors Affecting Its Continued for the purposes of conducting wildlife promote sustainable natural resources Existence studies. Such access restrictions might were often unattainable because of We briefly discussed the effects of prohibit further surveys, research, and conflicting land ownership interests introduced predation on pygmy-owls by monitoring of pygmy-owls on State (Valdez et al. 2006, p. 272). The domestic house cats in our Factor C Trust lands, due to new permit allocation of funds for management of analysis above. While this is a manmade requirements and substantial cost. This natural reserve areas in Sonora is factor affecting pygmy-owls, for Factor E has not been formally adopted and may precarious, and some reserves have not we will discuss human-caused mortality be changed prior to finalization (Latimer received protection other than that that is not associated with any of the 2010, p. 1). However, if implemented as given by government edicts or their other factors, for example, collisions described by Latimer (2010, p. 1), these natural isolation (Burquez and with fences, cars, and windows, and proposed procedures and fees would Martinez-Yrizar 1997, p. 378). Urban shooting. Natural factors affecting likely limit pygmy-owl research on State development has taken its toll on pygmy-owl habitat availability and Trust lands because of our and other Sonora’s natural reserves. Three of the suitability not related to Factor A will

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also be discussed under Factor E. These central Asia, and an increase in intense be refined, as will interpretations of include drought, climate change, tropical cyclone activity in the North projections, as more information hurricanes, and the effects of small Atlantic since about 1970 (IPCC 2007a, becomes available. For instance, some populations. p. 30); and an increase in annual changes in conditions are occurring average temperature of more than 2° F more rapidly than initially projected, Human-Caused Mortality (1.1°C) across US since 1960 (Global such as melting of Arctic sea ice Direct and indirect human-caused Climate Change Impacts in the United (Comiso et al. 2008, p. 1; Polyak et al. mortalities (e.g., collisions with cars, States (GCCIUS) 2009, p. 27). Examples 2010, p. 1797), and since 2000 the glass windows, fences, power lines, of observed changes in the physical observed emissions of greenhouse gases, introduced competitors and predators, environment include: An increase in which are a key influence on climate etc.), while likely uncommon, are often global average sea level, and declines in change, have been occurring at the mid- underestimated, and probably increase mountain glaciers and average snow to higher levels of the various emissions as human interactions with pygmy-owls cover in both the northern and southern scenarios developed in the late 1990’s increase (Banks 1979, pp. 13–14; Klem hemispheres (IPCC 2007a, p. 30); and used by the IPPC for making 1979, pp. 1–2; Churcher and Lawton substantial and accelerating reductions projections (e.g., Raupach et al. 2007, 1987, p. 439). This may be particularly in Arctic sea-ice (e.g., Comiso et al. Figure 1, p. 10289; Manning et al. 2010, important in areas of the pygmy-owl’s 2008, p. 1), and a variety of changes in Figure 1, p. 377; Pielke et al. 2008, range where pygmy-owls are located in ecosystem processes, the distribution of entire). Also, the best scientific and proximity to urban development. species, and the timing of seasonal commercial data available indicates that Documentation exists of pygmy-owls events (e.g., GCCIUS 2009, pp. 79–88). average global surface air temperature is flying into windows and fences, The IPCC used Atmosphere-Ocean increasing and several climate-related resulting in serious injuries or death to General Circulation Models and various changes are occurring and will continue the birds. In one incident, a pygmy-owl greenhouse gas emissions scenarios to for many decades even if emissions are collided with a closed window of a make projections of climate change stabilized soon (e.g., Meehl et al. 2007, parked vehicle; it eventually flew off, globally and for broad regions through pp. 822–829; Church et al. 2010, pp. but had a dilated pupil in one eye, the 21st century (Meehl et al. 2007, p. 411–412; Gillett et al. 2011, entire). indicating neurological injury as a result 753; Randall et al. 2007, pp. 596–599), Changes in climate can have a variety of this encounter (Abbate et al. 1999, p. and reported these projections using a of direct and indirect impacts on 58). In another incident, an adult framework for characterizing certainty species, and can exacerbate the effects pygmy-owl was found dead at a wire (Solomon et al. 2007, pp. 22–23). of other threats. Rather than assessing fence; apparently it flew into the fence Examples include: (1) It is virtually ‘‘climate change’’ as a single threat in and died (Abbate et al. 2000, p. 18). certain there will be warmer and more and of itself, we examine the potential AGFD also has documented an incident frequent hot days and nights over most consequences to species and their of individuals shooting BB guns at birds of the earth’s land areas; (2) it is very habitats that arise from changes in perched on a saguaro that contained an likely there will be increased frequency environmental conditions associated active pygmy-owl nest. The information of warm spells and heat waves over with various aspects of climate change. we have related to human-caused most land areas, and the frequency of For example, climate-related changes to mortality is limited to the United States heavy precipitation events will increase habitats, predator-prey relationships, and does not generally appear to be a over most areas; and (3) it is likely that disease and disease vectors, or significant effect on pygmy-owl increases will occur in the incidence of conditions that exceed the physiological populations. Information from Mexico extreme high sea level (excludes tolerances of a species, occurring does not indicate that these activities tsunamis), intense tropical cyclone individually or in combination, may are affecting pygmy-owls in a manner activity, and the area affected by affect the status of a species. different than the United States. droughts (IPCC 2007b, p. 8, Table Vulnerability to climate change impacts Drought and Climate Change SPM.2). More recent analyses using a is a function of sensitivity to those different global model and comparing changes, exposure to those changes, and ‘‘Climate’’ refers to an area’s long-term other emissions scenarios resulted in adaptive capacity (IPCC 2007, p. 89; average weather statistics (typically for similar projections of global temperature Glick et al. 2011, pp. 19–22). As at least 20- or 30- year periods), change across the different approaches described above, in evaluating the status including the mean and variation of (Prinn et al. 2011, pp. 527, 529). of a species, the Service uses the best surface variables such as temperature, All models (not just those involving scientific and commercial data precipitation, and wind, whereas climate change) have some uncertainty available, and this includes ‘‘climate change’’ refers to a change in associated with projections due to consideration of direct and indirect the mean and/or variability of climate assumptions used, data available, and effects of climate change. As is the case properties that persists for an extended features of the models; with regard to with all potential threats, if a species is period (typically decades or longer), climate change this includes factors currently affected or is expected to be whether due to natural processes or such as assumptions related to affected by one or more climate-related human activity (Intergovernmental emissions scenarios, internal climate impacts, this does not necessarily mean Panel on Climate Change (IPCC) 2007a, variability and differences among the species is a threatened or p. 78). Although changes in climate models. Despite this, however, under all endangered species as defined under the occur continuously over geological time, global models and emissions scenarios, Act. If a species is listed as threatened changes are now occurring at an the overall projected trajectory of or endangered, this knowledge accelerated rate. For example, at surface air temperature is one of regarding its vulnerability to, and continental, regional and ocean basin increased warming compared to current impacts from, climate-associated scales, recent observed changes in long- conditions (Meehl et al. 2007, p. 762; changes in environmental conditions term trends include: a substantial Prinn et al. 2011, p. 527). Climate can be used to help devise appropriate increase in precipitation in eastern parts models, emissions scenarios, and strategies for its recovery. of North American and , associated assumptions, data, and While projections from global climate northern Europe, and northern and analytical techniques will continue to model simulations are informative and

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in some cases are the only or the best reduction of riparian woodlands and because it will exacerbate the current scientific information available, various other pygmy-owl habitat elements. and ongoing effects discussed above. downscaling methods are being used to Smith et al. (2000, p. 79) noted the For example, drought has been provide higher-resolution projections following with regard to nonnative grass documented in Arizona and northern that are more relevant to the spatial invasions and climate change, ‘‘This Sonora to reduce juvenile pygmy-owl scales used to assess impacts to a given shift in species composition in favor of survival. Under the predicted climate species (see Glick et al, 2011, pp. 58– exotic annual grasses, driven by global change scenarios, drought will occur 61). With regard to the area of analysis [climate] change, has the potential to more frequently and increase in for the pygmy-owl, downscaled models accelerate the fire cycle, reduce severity. The invasion of nonnative predict that the Sonoran Desert biodiversity, and alter ecosystem species has been documented in the loss Ecoregion will be drier through the 21st function in the deserts of western North of pygmy-owl habitat and native century and that the transition to a more America.’’ vegetation communities. A common arid climate is likely already under way Changes in the timing of precipitation prediction under climate change is for (Seager et al. 2007, p. 1181). Future due to climate change may have effects conditions that will favor the increased drought is projected to occur under related to pygmy-owl prey availability occurrence and distribution of warmer temperature conditions as and abundance. Flesch (2008, p. 8) nonnative species. Riparian areas, both climate change progresses. Seager et al. found that timing and quantity of permanent and ephemeral, support (2007, p. 1181) predict that the recent precipitation affected both lizard and important pygmy-owl habitat elements multiyear droughts, the Dust Bowl, and rodent abundance in ways that such as thermal and predator cover, and 1950s drought conditions will become suggested rainfall is an important driver increased prey availability. Precipitation the new climatology of the American of population and community events under most climate change Southwest with a timeframe of years to dynamics. In general, cool-season scenarios will decrease in frequency and decades. Already, the current, multiyear rainfall had a positive correlation with increase in severity. This may reduce drought in the western United States, rodent populations and warm-season available cover and prey for pygmy-owls including most of the Southwest, is the rainfall was positively correlated with by affecting riparian areas through most severe drought recorded since lizard populations. Because various scouring flood events and reduced 1900 (Overpeck and Udall 2010, p. climate change models predict that moisture retention. However, the extent 1642). climate conditions will become more to which changing climatic patterns will Although specifically looking at variable, lizard species that are most affect the pygmy-owl is not known with pinyon-juniper communities, Breshears affected by variations in precipitation certainty at this time. et al. (2005, pp. 15147–15148) showed will tend to decline in abundance across that a particular concern under these time. This is an important finding given Hurricanes drought conditions is regional-scale that lizards are the primary prey item Although not generally considered a mortality of overstory trees, which for pygmy-owls during the summer. historical impact to pygmy-owl habitat, rapidly alters ecosystem type, associated The majority of the current range of the loss of habitat and nest structures as ecosystem properties, and land-surface the pygmy-owl occurs in tropical or a result of hurricanes has recently been conditions for decades. Woodlands subtropical vegetation communities that identified as a potential contributor to providing important pygmy-owl habitat, may be reduced in coverage if climate an apparent decline in pygmy-owl including meso- and xeroriparian trees, change results in hotter, more arid nestlings documented as part of an thornscrub, and tropical deciduous conditions. The Sonoran Desert ongoing pygmy-owl nest box study in forests may respond in a similar Ecoregion is already characterized by south Texas (Proudfoot 2011b, p. 1; manner. Gitlin et al. (2006, p. 1482) hot, arid conditions, and pygmy-owls in Proudfoot 2010, p. 1). Hurricanes within documented increased mortality of this portion of the range are already the past five years have impacted Populus fremontii (Fremont adapted to the hotter, more arid thousands of acres of occupied pygmy- cottonwood) (an important riparian tree conditions that may prevail in the owl habitat by removing trees and in Sonoran Desert mesoriparian future. This adaptation may be reducing cover and structural diversity. communities) during the recent drought. important to the continued existence of Within the current range of the pygmy- Northern areas of Mexico are most the subspecies as desertification spreads owl, hurricanes are most likely to affect vulnerable to droughts and in response to climate change, but may pygmy-owl habitat in southern Texas desertification because erosion and be offset as some future model scenarios and northeastern Mexico, although drought severity will increase with predict a reduction in columnar cacti hurricanes in the Pacific Ocean also higher temperatures and rainfall densities, the primary pygmy-owl have the potential to affect pygmy-owl variations in these arid and semi-arid nesting substrate within the Sonoran habitat in western Mexico. Historically, regions (Conde and Gay 1999, p. 2). The Desert Ecoregion (Weiss and Overpeck major hurricanes have made landfall in three Mexican regions most vulnerable 2005, p. 2074). Already studies have southern Texas on average about once to climate change are, in order of documented a noticeable shift north of every decade. However, more recently, importance, Central, Northern (in areas bird species in association with hurricanes (Erika in 2003, Dolly in 2008, occupied by pygmy-owls), and the changing climates. Christmas Bird and Alex in 2010) have occurred more Tabasco Coast (Conde and Gay 1999, p. Count data show a shift northward in 56 often than in the past, suggesting that 2). Magana and Conde (2000, p. 183) percent of the 305 most widespread, major hurricanes may be occurring more showed the vulnerability of northern regularly occurring wintering bird frequently now. If hurricanes continue Mexico, specifically Sonora, to species (NABCI 2010). This same report to occur every few years, this frequency interannual climate variability and indicates that bird species that are rare of hurricanes resulting in loss of climate change. They found that future or nonexistent in the United States at woodlands may not allow some areas of major challenges that will result from present will expand their ranges into previously suitable pygmy-owl habitat climate change are increasing demand our country from the south (NABCI to regenerate trees of adequate size to for water, competition among water 2009, p. 15). support the cavities needed for nesting users, and decline in water quality, Climate change may have a negative by pygmy-owls. However, the effects are along with the resultant loss or impact on some pygmy-owl populations expected to be localized.

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Scattered, Small Population Groups a population to respond to pygmy-owl populations from factors An important principle of environmental challenges (Keller et al. related to drought and small population conservation genetics is that small, 1994). size have been documented in portions isolated populations will experience Similarly, chance environmental and of the pygmy-owl’s range, specifically reductions in the health of the demographic events may pose a more Arizona. All but one model evaluating substantial threat to small populations population due to the expression of changing climatic patterns for the than to large populations (Westemeier et negative population characteristics as a southwestern United States and al. 1998, p. 1695). Caughley and Gunn result of inbreeding. Loss of individual northern Mexico predict a drying trend (1996, p. 166) noted that small adaptation can also occur and may for the region (Seager et al. 2007, pp. populations can become extinct entirely adversely affect population demography 1181–1184), which will negatively affect by chance even when their members are and increase the risk of population riparian and other plant communities healthy and the environment favorable. that provide habitat for pygmy-owls. extinction (Caughley 1994, p. 217). Demographic characteristics of small The extent to which changing climatic Inbreeding in small, isolated populations can be significant patterns will affect the pygmy-owl is not populations often occurs because of a contributors in determining minimum known with certainty at this time. lack of mates to choose from, not from viable population sizes. Viability of However, predicted impacts of climate preferential mating among related small populations is likely dependent change may exacerbate and intensify the individuals. This can lead to increased on both demography and population effects of long-term drought and other chances that both parents will genetics and should not be considered negative impacts within the range of the contribute genes containing harmful independently (Keller et al. 2002, p. pygmy-owl identified under Factor A. traits, some of which may affect 356; Lande 1988, p. 1459). One concern in the northwestern important adaptive and physiological Consequently, for those areas of the portion of the species’ range is the characteristics, such as survival, pygmy-owl’s range where local small potential decline in large columnar fertility, and physiological vigor (Soule population size is an issue, if the result cacti, an essential pygmy-owl habitat and Mills 1998, p. 1658). of any of the above factors negatively element that provides nest sites. Inbreeding has been documented affects pygmy-owl demography or However, given the persistence of within the small pygmy-owl population genetics, effects, at least at the local pygmy-owl populations in the more arid in Arizona (Abbate et al. 2000, p. 21). population scale, may be significant. areas of its range (northwestern Mexico Lack of genetic diversity has also been Genetic rescue within a and Arizona), pygmy-owls in these areas documented during recent genetics metapopulation structure can occur may provide the genetic adaptations studies (Proudfoot and Slack 2001, pp. through periodic immigration into necessary to adapt to changing 5–7). Loss of isolated population groups small, inbred, at-risk populations and conditions. has occurred in Arizona due to lack of can alleviate inbreeding depression and Given the current pygmy-owl productivity and inadequate dispersal boost fitness, but habitat connectivity population status, the effects of small (AGFD 2008, p. 1). In 2008, a possible and adequate dispersal opportunities population size are likely to continue, genetic heart condition was diagnosed must be present. However, immigration especially in the northern portion of the in the mortality of three related pygmy- of genetically divergent individuals can range. Reduced population connectivity owls in the captive breeding research lead to the opposite effect—a reduction as a result of habitat impacts identified project, a possible expression of the in population fitness due to outbreeding under Factor A will likely continue to detrimental effects of the inbreeding of depression (when crosses between increase the potential for inbreeding and pygmy-owls in Arizona (Fox 2008, p. 1). individuals from different populations the associated loss of genetic diversity. In addition to genetic factors, habitat have lower fitness than progeny from At least in Arizona, lack of dispersing degradation or human-caused mortality crosses between individuals within the juveniles and floating nonbreeding can cause shifts in population same population) (Tallmon et al. 2004, individuals in the population due to characteristics that drive population p. 489). low numbers of breeding pygmy-owls decline. Genetic factors may simply In conclusion, small population size will also affect long-term occupancy of hasten the extinction process once a and inadequate dispersal, as well as a breeding territories and further erode population is small (Miller and Waits reduced ability to adapt due to low the metapopulation structure in Arizona 2003, p. 4334). In the face of ongoing genetic diversity, can result in increased and northern Sonora. However, these loss and fragmentation of habitat, the vulnerability of extinction for pygmy- effects appear to be localized, and we do potential for inbreeding increases as owls in small, isolated populations. The not find that impacts under Factor E are populations or groups of pygmy-owls best information we have indicates that significantly affecting pygmy-owls are increasingly isolated. This increases small, isolated populations probably rangewide. Based upon our review of the need for management that occur in Arizona, Texas, and the best commercial and scientific data maintains, restores, or substitutes for northeastern Mexico. We know of no available, we conclude that other historical patterns of between- small, isolated populations in southern natural and manmade factors are not population gene flow (Hogg et al. 2006, Mexico, and thus conclude that small immediate threats to the pygmy-owl p. 1491). In addition to inbreeding, population size is not likely to be a rangewide, and are not likely to become genetic drift (a change in the gene pool threat in that area. so in the future. of a population that takes place strictly by chance) in small populations can Summary of Factor E Pygmy-Owl Finding Throughout Its depress population fitness and increase In summary, direct, human-caused Range extinction risk (Tallmon et al. 2004, p. mortality of pygmy-owls can occur and As required by the Act, we conducted 489), as well as diminish future may, locally, have some impact on a review of the status of the species and adaptations to a changing environment isolated population segments. However, considered the five factors from section (Lande 1988, p. 1455). A significant loss it is unlikely that direct human-caused 4(a) in assessing whether the pygmy-owl in genetic variation within small mortality will have significant is threatened or endangered throughout populations may decrease population population-level impacts on the pygmy- all of its range. We examined the best health or limit the long-term capacity of owl throughout its range. Impacts to scientific and commercial information

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available regarding the past, present, United States, and in Sinaloa and Although it appears there are localized and future threats faced by the species. Sonora in Mexico can be used to help declines in pygmy-owl populations in We reviewed the petition, information us determine the general population Arizona and, possibly Texas and available in our files, other available status of the pygmy-owl throughout its northern Sonora, there does not appear published and unpublished range. The best available information we to be an ongoing, significant, long-term information, and we consulted with have indicates that local populations of decline in range-wide pygmy-owl species and subject experts, including pygmy-owls in Arizona, northern numbers that would lead us to believe peer review, and other Federal, State, Sonora, and Texas have likely the subspecies is currently in danger of Tribal, and local agencies. experienced population declines; extinction or likely to become so In considering what factors might however, the pygmy-owl is still found throughout its range due to factors constitute threats, we must look beyond in these areas. Pygmy-owls are still identified in our five-factor analysis. the mere exposure of the species to the found in southern Mexico, and the best We also considered whether any of factor and determine whether the available information indicates that they the negative impacts began recently species responds to the factor in a way may remain relatively common enough that their effects are not yet that causes actual impacts to the throughout this area. Based on the level manifested in current subspecies’ species. If there is exposure to a factor, of information we do have, it appears population numbers, but are likely to but no response, or only a positive pygmy-owls persist in most areas where have an effect in the foreseeable future. response, that factor is not a threat. If they have been historically documented Impacts from climate change are a there is exposure and the species in the literature and during recent particular impact that has recently been responds negatively, the factor may be survey efforts. The most recent IUCN accelerating. These effects are so recent a threat and we then attempt to (International Union for Conservation of that we have no information on the determine how significant a threat it is. Nature) Red List (an international long-term effects to pygmy-owl If the threat is significant, it may drive standard for species extinction risk) populations. However, drought is or contribute to the risk of extinction of contains the following statement with predicted to become more prevalent the species such that the species regard to the status of the ferruginous within the Sonoran range of the pygmy- warrants listing as threatened or pygmy-owl, ‘‘Despite the fact that the owl, and drought has had a historically- endangered as those terms are defined population trend appears to be negative impact on pygmy-owl by the Act. This does not necessarily decreasing, the decline is not believed populations in this area. The require empirical proof of a threat. The to be sufficiently rapid to approach predictions of drought throughout the combination of exposure and some thresholds for Vulnerable under the remainder of the range are uncertain; corroborating evidence of how the population trend criterion (greater than however, as discussed under Factor E, species is likely impacted could suffice. a 30 percent decline over ten years or pygmy-owls in the northern portion of The mere identification of factors that three generations).’’ (IUCN 2008, p. 2). their range may be more resilient and could impact a species negatively is not So, while this statement may be an better adapted to drought conditions. sufficient to compel a finding that indication of a range-wide population Other impacts are largely limited to listing is appropriate; we require decline, it does not appear that such a specific portions of the subspecies’ evidence that these factors are operative decline is significant enough to place range, and we do not believe they would threats that act on the species to the the pygmy-owl in a category of concern manifest their future effects as range- wide population declines. Therefore, point that the species meets the for IUCN. In addition, this statement definition of threatened or endangered the pygmy-owl is not currently in applies to ferruginous pygmy-owls as a under the Act. danger of extinction, or likely to become species, and does not separate status for Through our five-factor analysis, we so, due to potential threats that began the individual subspecies. Therefore, identified a number of factors that are recently enough that their long-term based on the best available scientific negatively affecting the pygmy-owl, effects are not yet manifest. including the following: (1) Habitat loss and commercial information, we do not Next, we considered whether any of and fragmentation due to urbanization, find evidence of a sufficient declining the current negative factors are likely to improper grazing, nonnative-species trend in the subspecies’ population to increase within the foreseeable future, invasions and associated changes in fire indicate it is in danger of range-wide such that the species is likely to become regimes, OHV use, agricultural extinction now, or in the foreseeable in danger of extinction in the development, and wood cutting; (2) future. In other words, based on a foreseeable future. We do believe that border issues; (3) inadequate regulatory review of the best available data, the some of the negative factors identified mechanisms; (4) drought and climate data do not suggest that the combined will increase in the foreseeable future change; and (5) small size of some local effects of the negative impacts discussed including urbanization, nonnative populations. To determine whether in our five-factor analysis are resulting invasions and fires, agricultural these factors individually or collectively in an overall, long-term reduction in the development, woodcutting, grazing, and rise to a ‘‘threat’’ level such that the distribution of the pygmy-owl, or an climate extremes. However, as pygmy-owl is in danger of extinction associated significant range-wide discussed above in our five-factor throughout its range, or likely to become decline in pygmy-owl numbers, such analysis, these impacts occur in a so in the foreseeable future, we first that the subspecies is currently in limited portion of the range, primarily considered whether these negative danger of extinction or likely to become Arizona, Texas, and Sonora. For the factors to the subspecies were causing so. remaining portions of Mexico, the best long-term, range-wide, population-scale There are severe impacts to certain available information indicates that the declines in pygmy-owl numbers, or portions of the pygmy-owl’s range. negative factors are less severe or that were likely to do so in the foreseeable However, those impacts are restricted to there is no evidence of the negative future. a relatively small (27 percent) portion of impact. The best available information While range-wide surveys have not the entire range. We found no evidence also indicates that pygmy-owls are been conducted for the pygmy-owl, that these impacts are of sufficient relatively common in this portion, information from surveys that have been magnitude and severity to affect the which is 73 percent of their range. conducted in Texas and Arizona in the rangewide population of pygmy-owls. Therefore, we conclude that there is no

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evidence that negative factors, such as After determining the subspecies is importance to the taxon to which it urbanization, agricultural development, not currently in danger of extinction or belongs. Since precise circumstances are or woodcutting, will increase in the likely to become so in the foreseeable likely to vary considerably from case to foreseeable future in the majority of the future throughout its range, we next case, the DPS policy does not describe pygmy-owl’s range. consider whether a distinct vertebrate all the classes of information that might Finally, we considered whether population segment (DPS) or whether be used in determining the biological stochastic events might decrease the any significant portion of the pygmy and ecological importance of a discrete long-term viability of the species owl’s range is in danger of extinction or population. However, the DPS policy (species viability requires a naturally- is likely to become so in the foreseeable describes four possible classes of reproducing population large enough to future. information that provide evidence of a maintain sufficient genetic variation to population segment’s biological and Distinct Vertebrate Population Segment provide for its continued evolution and ecological importance to the taxon to response to natural environmental Under the Service’s Policy Regarding which it belongs. As specified in the changes). We considered whether, given the Recognition of Distinct Vertebrate DPS policy (61 FR 4722), this a currently stable population range- Population Segments Under the consideration of the population wide, is the pygmy-owl likely to become Endangered Species Act (61 FR 4722, segment’s significance may include, but in danger of extinction in the February 7, 1996), three elements are is not limited to, the following: foreseeable future because stochastic considered in the decision concerning (1) Persistence of the discrete events might reduce its current numbers the establishment and classification of a population segment in an ecological to a point where its long-term viability possible DPS. These are applied setting unusual or unique to the taxon; would be in question. Current similarly for additions to or removal (2) Evidence that loss of the discrete information suggests that stochastic from the Federal List of Endangered and population segment would result in a events such as hurricanes, extreme Threatened Wildlife. These elements significant gap in the range of a taxon; drought, and catastrophic fires could include: (3) Evidence that the discrete reduce the viability of local pygmy-owl (1) The discreteness of a population in population segment represents the only populations in Arizona, Texas, and relation to the remainder of the species surviving natural occurrence of a taxon northern Sonora. However, because of to which it belongs; that may be more abundant elsewhere as the pygmy-owl’s wide distribution and (2) The significance of the population an introduced population outside its historical indications of relatively segment to the species to which it historic range; or higher numbers throughout most of its belongs; and (4) Evidence that the discrete range, even if a stochastic event were to (3) The population segment’s population segment differs markedly occur within the foreseeable future that in relation to the from other populations of the species in negatively affected this subspecies, the Act’s standards for listing. delisting, or its genetic characteristics. range-wide population would still be reclassification (i.e., is the population A population segment needs to satisfy unlikely to fall to such a low level that segment endangered or threatened). only one of these conditions to be it would be in danger of extinction. considered significant. Furthermore, Discreteness Despite some regional declines in other information may be used as pygmy-owl population numbers, the Under the DPS policy, a population appropriate to provide evidence for subspecies has been able to maintain segment of a vertebrate taxon may be significance. what appears to be range-wide considered discrete if it satisfies either population viability. Negative factors one of these conditions: Analysis of Potential Distinct affecting pygmy-owls seem to be (1) It is markedly separated from other Population Segments restricted, for the most part, to a populations of the same taxon as a The petitioners requested that we relatively small portion of its range. The consequence of physical, physiological, consider two potential DPS’s of the areas where we have detailed ecological, or behavioral factors. pygmy-owl for protection under the Act, information to evaluate potential threats Quantitative measures of genetic or a Sonoran Desert DPS and an Arizona and pygmy-owl population status morphological discontinuity may DPS. The petitioners did not suggest any (Arizona, Texas, and Sonora) represent provide evidence of this separation. additional DPS configurations to be approximately 27 percent of the overall (2) It is delimited by international evaluated. However, in order to be pygmy-owl range. The best available governmental boundaries within which complete in our analysis of potentially information suggests that the range-wide differences in control of exploitation, listable pygmy-owl entities, we also pygmy-owl population is not management of habitat, conservation considered other potential DPS significantly declining, despite regional status, or regulatory mechanisms exist configurations including an eastern/ changes in population numbers, and that are significant in light of section western DPS and a Texas DPS. Our that most of the immediate impacts to 4(a)(1)(D) of the Act. analysis of these two other potential the pygmy-owl and its habitats are DPS configurations follows our Significance geographically concentrated. In evaluation of the petitioned DPS summary, based on our review of the If a population segment is considered configurations. best available scientific and commercial discrete under one or more of the information pertaining to the five conditions described in the Service’s Potential Sonoran Desert DPS factors, we find that threats throughout DPS policy, its biological and ecological As described, none of the boundaries the majority of the pygmy-owl’s range significance will be considered in light of the petitioner’s Sonoran Desert DPS are not of sufficient imminence, of Congressional guidance that the include an international border or severity, or magnitude to indicate that authority to list DPSs be used boundary (CBD and DOW 2007, pp. 4– the pygmy-owl is in danger of extinction ‘‘sparingly’’ while encouraging the 6) (Figure 4). Therefore, the petitioned (endangered), or likely to become conservation of genetic diversity. In DPS must meet the first condition for endangered within the foreseeable making this determination, we consider discreteness in order to be considered a future (threatened), throughout all of its available scientific evidence of the valid DPS, because it does not meet the range. discrete population segment’s second condition. The eastern and

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western portions of the range of the evidence that there are marked subject of litigation and, ultimately, the pygmy-owl are separated by the Sierra behavioral, morphological, or same DPS configuration that the Service Madre and other mountain ranges in physiological differences within the removed from the Federal List of north-central Mexico (Proudfoot et al. petitioned DPS (AGFD 2008a, pp. 1–4). Endangered and Threatened Wildlife in 2006a, p. 9). However, there are no As a result, this study indicates that 2006 (71 FR 19452; April 24, 2006) obvious physical or geographic barriers there is no marked genetic or (Figure 4). That final rule presents our that separate the petitioned Sonoran morphological separation between the analysis showing that, while the Desert DPS from the rest of the pygmy- petitioned Sonoran Desert DPS and discreteness criteria for the DPS were owl’s range to the south. There is a southern Sonora populations (Proudfoot met, we could not show that this DPS documented area in central Sonora, near 2009a, p. 1; AGFD 2008a, p. 10). was significant to the taxon as a whole. Hermosillo, Mexico, that may act as an The Sonoran Desert Ecoregion does The petition states that ‘‘the Arizona impediment to pygmy-owl movements differ ecologically from the remainder of DPS occurs in a unique ecological and dispersal, because of the lack of the areas within its range. Despite the setting and differs markedly in its contiguous suitable habitat resulting fact that occurrence of some plant genetic characteristics from pygmy-owls from natural and artificial conditions species overlaps with other ecoregions in Sinaloa and elsewhere in the species (Flesch 2003, pp. 40, 100). However, the to the south and east, the Sonoran range. Loss of the Arizona DPS would extent of this band of unsuitable habitat Desert is a unique dry desert area that also create a significant gap in the does not prevent regular or occasional does function ecologically in a different species’ range, resulting in loss of movements by pygmy-owls between way when compared to adjacent roughly a third of the subspecies’ range, northern and southern Sonora. This is ecoregions. However, as described and half of the species’ range in the supported by genetic sampling and above, the best available scientific and Sonoran Desert. The Arizona DPS is also analysis that has recently been commercial data do not indicate that significant because it represents the completed, that indicates that there is this ecological difference has resulted in entire range of G. ridgwayi cactorum in likely gene flow between the two groups any morphological, physiological, or the United States’’ (CBD and DOW 2007, (Proudfoot 2009a, p. 1). genetic differentiation within pygmy- p. 12). Proudfoot’s earlier assessment of owl populations in the Sonoran Desert. Our analysis in the final rule to delist mitochondrial DNA (mtDNA) and Environmental characteristics within the pygmy-owl showed that the then- microsatellite DNA of pygmy-owls from the Sonoran Desert have likely resulted listed Arizona DPS of the pygmy-owl Arizona, Sonora, and Sinaloa implied in the reduced numbers and densities of was not markedly different in its genetic restricted gene flow between the pygmy-owls found in this area. characteristics from pygmy-owls in Sonoran and Sinaloan populations However, this does not appear to have northern Sonora, Mexico; did not occur (Proudfoot et al. 2006a, p. 10; Proudfoot resulted in any physical differentiation, in a unique ecological setting; nor et al. 2006b, p. 9). However, the authors at least anecdotally, from adjacent would loss of the DPS represent a implied that limited sampling and pygmy-owl populations. significant gap in the range of the taxon geographic distance between sample We find that there is no evidence that (71 FR 19452). We are unaware of any sites in Sonora and Sinaloa may have the Sonoran Desert population of scientific information compiled since influenced the results of these studies. pygmy-owl is markedly separated in any the delisting that would alter the To verify the inference of restricted gene way from the remainder of the taxon. conclusions made in that final rule. flow, a joint effort among Proudfoot, Therefore, we determine, based on a Therefore, we determine, based on a AGFD, and the Service resulted in the review of the best available information, review of the best available information, collection and analysis of an additional that the petitioned Sonoran Desert DPS that the petitioned Arizona DPS of the 119 samples collected in areas not of the pygmy-owl does not meet the pygmy-owl does not meet the previously sampled (Proudfoot 2009, p. discreteness conditions of the 1996 DPS significance conditions of the 1996 DPS 1; AGFD 2008a, pp. 1–10). Analysis of policy. As such, this population policy. Therefore, this population the genotypic variation revealed segment does not qualify as a DPS under segment does not qualify as a DPS under isolation by distance with significant our policy and is not a listable entity our policy and is not a listable entity gene flow between pygmy-owl under the Act. under the Act. populations. Estimates of migrants per The DPS policy indicates that generation time for pygmy-owl significance should be analyzed only if Potential Texas DPS populations were 8.62 (Arizona-Sonora), a population segment has been We have reviewed new information 6.65 (Arizona-Sinaloa) and 23.46 identified as discrete. Because we found regarding the status of the pygmy-owl in (Sonora-Sinaloa) (Proudfoot 2009, p. 1). that the Sonoran Desert population Texas (Proudfoot 2010, p. 1; 2011b, p. So, while no haplotypes from segment did not meet the discreteness 1). In addition, the peer reviewers of the Arizona, Sonora, or Sinaloa are shared element and, therefore, does not qualify current genetic information provided with the remainder of Mexico and as a DPS under the Service’s DPS insight and recommendations regarding Texas, there are shared haplotypes policy, we will not conduct an the genetic diversity and management of among Arizona, Sonora, and Sinaloa, evaluation of significance. pygmy-owls in Arizona and Texas. indicating there is exchange of genetic Upon consideration of this new Potential Arizona DPS material within this grouping (Proudfoot information, we concluded that it was et al. 2006a, p. 7). This would argue Because we are evaluating this appropriate to evaluate a potential against the Sonoran Desert Ecoregion petitioned entity based on the currently Texas DPS that includes the current being markedly separate from the accepted taxonomic classification of the range of the pygmy-owl in Texas to the remainder of Sonora and Sinaloa. Based pygmy-owl (see Description and international border with Mexico. on observations of pygmy-owls during Taxonomy section above), the taxon survey and capture activities in Arizona, considered in this finding is the same as Discreteness and in both northern and southern for our 1997 listing of the pygmy-owl The use of the international border to Sonora as described above, the best (62 FR 10730). Consequently, the define discreteness of the Arizona available scientific and commercial data petitioned Arizona DPS is exactly the pygmy-owl DPS was upheld by the does not indicate that there is any same DPS configuration that was the courts (No. 02–15212, CV00–0903 SRB

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at 11586, 2003) because of the Sonora (within thornscrub and tropical of unsuitable habitat (Chihuahuan differences in status and management of deciduous forests) are common and desert and grasslands, oak and pine the pygmy-owl between Arizona and likely number on the order of forests) and elevations greater than Mexico. Defining the discreteness of the thousands, while further north within 1,200 m (4,000 ft) associated with Texas DPS is appropriate using the same the Sonoran Desert Ecoregion, they are various mountain ranges. There has rationale. For example, Mexico has no fewer in number, more patchily never been any record of occurrence for regulations or laws specifically distributed, and likely number on the pygmy-owls in the area between south protecting the pygmy-owl. In Texas, the order of hundreds (Flesch 2003, pp. 39– Texas and Tucson, Arizona. In Mexico, pygmy-owl is listed as threatened, and 42; AGFD 2008a, p. 6). Given that the this distribution is separated throughout State law prohibits take without the majority of the pygmy-owl’s range its entirety by the Sierra Madre appropriate permit. Therefore, we appears to support similar numbers and Occidental and the Sierra Madre determine that the Texas DPS is discrete densities of pygmy-owls as Texas, we do Oriental. These mountain ranges extend due to differences in status and not believe that the loss of the south beyond the southern boundary of management of the pygmy-owl between population in Texas would represent a the described range of this subspecies the United States, in Texas, and Mexico. significant gap from the perspective of and represent a significant geographical Significance contribution to overall pygmy-owl barrier between the eastern and western population numbers. segments of the distribution (Cartron et The best available scientific and While there is some evidence that the al. 2000, p. 6). The elevational range of commercial information does not Texas population of pygmy-owls peaks in these mountain ranges is from indicate that the Texas population of contributes key genetic diversity to the 1,880 m to over 3,600 m (6,000 ft to over pygmy-owls occurs in an ecological overall population of pygmy-owls and 12,000 feet). Given the elevational limits setting that is unusual or unique to the is, to some extent, genetically unique of the pygmy-owl’s distribution within taxon. For example, the vegetation (Proudfoot 2006a, p. 7; Cicero 2008, p. its range (Freidman et al. 1950, pp. 145– community that supports pygmy-owls 2; Oyler-McCance 2008, pp. 1–2; 147), and the fact that pygmy-owls are in Texas is classified as Tamaulipan Dumbacher 2008, p. 9), the best replaced by the least pygmy-owl (G. brushland (Jahrsdoerfer and Leslie 1988, available scientific and commercial minutissimum), Colima pygmy-owl (G. p. 1). This vegetation community and information suggests that pygmy-owls in palmarum), and the northern pygmy- the associated pygmy-owl habitat Texas are genetically similar to pygmy- owl (G. gnoma) at higher elevations elements are found in southern Texas owls across the international border in (Schaldach 1963, p. 40; Howell and and northeastern Mexico (Jahrsdoerfer Mexico (Proudfoot 2006a, pp. 9–10). Robbins 1995, pp. 19–20), mountains and Leslie 1988, pp. 1–9; Hunter 1988, This lack of genetic differentiation from with elevations as significant as those p. 8; Cook et al. 2001, pp. 1–2) and adjacent pygmy-owl populations separating the eastern and western comprise most of the eastern portion of suggests that the Texas population portions of the pygmy-owl’s distribution the pygmy-owl’s current range. Texas segment does not differ markedly from in Mexico represent a significant represents approximately 15 percent of adjacent populations of pygmy-owls. physical barrier, as discussed in the the eastern portion of the range of the Proudfoot et al. (2006a, p. 7) indicated Service’s DPS policy (61 FR 4725). The pygmy-owl. In other words, that Texas is characterized by a single eastern and western portions of the approximately 85 percent of the pygmy- haplotype; and that one haplotype is current distribution of cactorum never owl habitat that is characterized as shared with pygmy-owls from meet (Figure 1). Tamaulipan brushland occurs outside of Tamaulipas, Mexico, indicating there Texas. Therefore, the Texas population Recent evaluation of genetic has been some exchange of genetic of pygmy-owls does not occur in an characteristics appears to indicate that material. Based on the best available unusual or unique setting for the taxon. the eastern and western portions of the Texas represents approximately 5 scientific and commercial information, pygmy-owl’s current distribution differ percent of the overall range of the we do not find that the Texas DPS is from each other genetically (Proudfoot pygmy-owl. From a geographic significant to the taxon as a whole, and et al. 2006b, pp. 7–9). As we have perspective, loss of this portion of the is, therefore, not a listable entity under discussed previously in this document, range does not represent a significant the Act. No further analysis of the Texas this genetic differentiation may not be gap in the range of the pygmy-owl. DPS is warranted at this point. adequate to define a subspecies, but it However, we must also consider where Potential Western and Eastern DPSs does provide further evidence that the the loss of the contribution of this eastern and western portions of the population segment to overall Discreteness pygmy-owl’s range are markedly population numbers would represent a The current range of the , separate. There is genetic evidence that significant gap in the range. Pygmy-owl as discussed above, is defined as the western group containing this population estimates for Texas range occurring from lowland central Arizona portion of the range does group closer from 100 owls in Kleberg County south through western Mexico to the together than it does to owls in the (Tewes 1992, p. 24), to 654 pairs in States of Colima and Michoaca´n, and eastern portion of the overall range. Kenedy, Brooks, and Willacy Counties from southern Texas south through the Proudfoot (2006a, p. 7) indicates that (Wauer et al. 1993, p. 1074), and 745 to Mexican States of Tamaulipas and pygmy-owls in this portion of the range 1,823 pygmy-owls on ranches in Kenedy Nuevo Leon (Johnsgard 1988, p. 159; share no haplotypes with populations in and Brooks Counties (Mays 1996, p. 32). Millsap and Johnson 1988, p. 137; Texas or in the remainder of Mexico. This is considerably higher than Oberholser 1974, p. 452; Friedmann et Additionally, in considering the work of population estimates in Arizona al. 1950, p. 145), consistent with the last Proudfoot et al. (2006a and 2006b), (approximately 50 owls (Abbate et al. American Ornithologist Union (AOU) expert review concluded that, based on 2000, pp. 15–16)), but likely similar to list that addressed avian classification to evidence of restricted gene flow the densities occurring in thornscrub the subspecies level (AOU 1957). In the between the Arizona/western Mexico and dry tropical forest habitats further United States, the eastern and western and Texas/eastern Mexico populations, south in Mexico. Field data indicate that portions of the pygmy-owl’s range are Arizona and Texas should be managed pygmy-owls in the southern portions of separated by over 1,600 km (1,000 mi) as separate units and should be

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considered genetically distinct (Cicero urbanization, improper grazing, following occur within the eastern 2008, p. 2; Oyler-McCance 2008, pp. 1– nonnative species invasions, fire, portion of the pygmy-owl’s range: (1) 2; Dumbacher 2008, p. 9), indicating agricultural development, and wood Habitat loss and fragmentation due to that Arizona and Texas, as portions of cutting; (2) border issues; (3) inadequacy urbanization, improper grazing, the western and eastern distributions of of existing regulatory mechanisms; (4) nonnative species invasions, fire, the pygmy-owl, contribute to the drought and climate change; (5) agricultural development, and wood respective genetic diversity of each of predation; and (6) small population size. cutting; (2) loss or alteration of habitat these regions. Therefore, we find that Therefore, within the potential western as a result of hurricanes; (3) lack of the eastern and western portions of the DPS configuration, impacts to pygmy- adequate regulatory mechanisms; (4) range of Glaucidium brasilianum owls and their habitat discussed under drought and climate change; (5) cactorum are markedly separated from factors A, C, and E may be affecting this predation; and (6) small population size. each other as a consequence of physical pygmy-owl population segment. Therefore, within the potential eastern and ecological factors. As such, we Despite the potential effects of these DPS configuration, impacts to pygmy- determine that the eastern and western impacts within the western portion of owls and their habitat discussed under portions of the current distribution of the pygmy-owl’s range, low population factors A, C, E may be affecting this the pygmy-owl are discrete (Figure 4). numbers, and apparent population pygmy-owl population segment. declines in local pygmy-owl The historical loss of pygmy-owl Significance populations in the northern portion of habitat in the eastern portion of its range The Service’s DPS policy indicates this population segment, the best has had significant effects on the that one of the ways a DPS may be available scientific and commercial data pygmy-owl. As discussed above, the significant to the taxon as a whole is if indicate that pygmy-owls remain pygmy-owl was once a common the loss of the DPS would result in a common in the majority of the western breeding species in Texas and significant gap in the range of the taxon portion of the pygmy-owl’s range. northeastern Mexico (Griscom and (61 FR 4725). A gap in the range can be Recent survey and monitoring in Sonora Crosby 1926, p. 18; Friedmann et al. interpreted as a physical gap, but may indicated that the highest densities of 1950, p. 145), but is now extirpated or also be considered to be a gap in the pygmy-owls occurred in the Sinaloan extremely rare in the area of the Rio continuous cline of genetic variation deciduous forest of southern Sonora Grande Delta (Oberholser 1974, pp. found within the distribution of the (Flesch 2003, p. 42). During capture 451–452). However, a disjunct species. With regard to the pygmy-owl, efforts in 2008, AGFD (2008, p. 6) population generally occurring in the the western portion of the range documented multiple pygmy-owls area of Kenedy County, Texas, has been comprises approximately 68 percent of commonly responding at capture sites estimated at 100 pygmy-owls (Tewes the entire range of the taxon and, in the thornscrub and tropical 1992, p. 24), 654 pairs (Wauer et al. consequently, the eastern portion of the deciduous forests of southern Sonora 1993, p. 1074), and up to 1,823 pygmy- range represents approximately 32 and northern Sinaloa, an occurrence owls (Mays 1996, p. 32). It should be percent of the range. Physically, the loss which only rarely happened further noted that these studies used different of either of these geographic areas north in Sonoran desertscrub habitats. methodologies and study areas, and are represents a significant gap in the While anecdotal, it appears that the not directly comparable, but do provide distribution of the taxon. In addition, number and density of pygmy-owls is estimates for the general area. A recent Proudfoot et al. (2006a and 2006b) higher in the thornscrub and deciduous concern about the populations in Texas indicate that the genetic characteristics forest community types than in the has been raised because of an apparent of the pygmy-owl may vary from Texas Sonoran Desert community type. This decline in the number of pygmy-owl to Arizona as a cline of variation based occurrence and distribution agrees with nestlings banded in this population as on distance of separation. Loss of either past conclusions found in the literature part of an ongoing nest box study in the western or eastern portion of this (Hunter 1988, p. 7; Russell and Monson Texas (Proudfoot 2010, p. 1). However, cline represents a significant gap in the 1988, p. 141; Shaldach 1963, p. 40). comprehensive pygmy-owl surveys distribution of genetic variation within Because pygmy-owl habitat in the throughout southern Texas have not the overall pygmy-owl population. southern portion of the western occurred for over a decade, and, without Therefore, the loss of the current range population segment is primarily a more comprehensive survey effort in of the pygmy-owl as represented by the thornscrub and dry tropical forests, it southern Texas, we cannot definitively western and eastern portions of the logically follows that pygmy-owls are state that the overall population of current range, and the loss of a more common in this portion of the pygmy-owls in southern Texas matches substantial portion of the genetic population segment. Based upon our the decline of nestlings documented variation represented within the taxon review of the best available commercial during this nest box study. Pygmy-owls as a whole, would result in a significant and scientific data, we conclude that may simply have moved to other areas gap in the range of the pygmy-owl. As pygmy-owl population numbers are not supporting suitable nesting habitat such, we find that the eastern and being significantly affected by the (Proudfoot 2011b, p. 1). western population segments are identified negative impacts in most of While the literature indicates that significant, based on evidence that loss the western portion of the pygmy-owl’s significant areas of pygmy-owl habitat of the discrete population segment range such that the population is in have been lost and fragmented would result in a significant gap in the danger of extinction or likely to become throughout the eastern portion of the range of a taxon. so in the foreseeable future. Therefore, pygmy-owl’s range, there is no we find that listing a western DPS of the indication that, where areas of suitable Determination for the Potential Western overall pygmy-owl population is not habitat remain, numbers and densities DPS warranted under the Act. of pygmy-owls would not be similar to Of the negative impacts we identified those found in the same type of habitat in our 5-factor analysis above, the Determination for the Potential Eastern in Texas. Numbers of pygmy-owls in following occur within western portions DPS Texas remain substantially higher than of the pygmy-owl’s range: (1) Habitat Of the negative impacts we identified those in the northwestern portion of the loss and fragmentation due to in our 5-factor analysis above, the pygmy-owl’s range, and similar to the

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apparently higher numbers found in the defined ‘‘species’’: Defenders of Wildlife key definitions of the Act. This southwestern portion of the range in v. Salazar, 729 F. Supp. 2d 1207 (D. interpretation does not conflict with thornscrub and dry tropical forests. Mont. 2010), concerning the Service’s established past agency practice (prior Additionally, while urbanization and delisting of the Northern Rocky to the 2007 Solicitor’s Opinion, which agricultural development and Mountain gray wolf (74 FR 15123; Apr. interpreted language in section 4(c) as woodcutting may be ongoing negative 12, 2009); and WildEarth Guardians v. limiting the application of ESA impacts in northeastern Mexico Salazar, 2010 U.S. Dist. LEXIS 105253 protections to the significant portion of (AQUASTAT 2007, p. 2; Cook et al. (D. Ariz. Sept. 30, 2010), concerning the a species’ range where it is endangered 2001, p. 4; Jahrsdoerfer and Leslie 1985, Service’s 2008 finding on a petition to or threatened, rather than throughout its p. 17; Tewes1993, pp. 28–29), the list the Gunnison’s prairie dog (73 FR range) because no consistent, long-term occurrence of the majority of suitable 6660; Feb. 5, 2008). The Service had agency practice has been established, pygmy-owl habitat in Texas on private asserted in both of these determinations and it is consistent with the most recent ranches may reduce the potential for that it had authority under the Act to judicial opinions that have most closely these impacts to significantly affect protect only some members of a examined this issue. Having concluded pygmy-owl populations in this area. ‘‘species,’’ as that term is defined by the that the phrase ‘‘significant portion of Wauer et al. (1993, p. 1076) state, Act (i.e., species, subspecies, or DPS). its range’’ provides an independent ‘‘Changes in the ranch land habitats of Both courts ruled that the basis for listing and protecting the entire Kenedy and Brooks Counties have been determinations were arbitrary and species, we next turn to the meaning of relatively limited, suggesting that capricious on the grounds that this ‘‘significant’’ to determine the threshold rancher landowners, at least in south approach violated the plain and for when such an independent basis for Texas, are being good land stewards.’’ unambiguous language of the Act. The listing exists. At least currently, the Texas population courts concluded that reading the SPR Although there are potentially many of pygmy-owls appears to be viable language to allow protecting only a ways to determine whether a portion of (Wauer et al. 1993, p. 1071) and the portion of a species’ range is a species’ range is ‘‘significant,’’ we primary recruitment base for pygmy-owl inconsistent with the Act’s definition of conclude, for the purposes of this populations in this area (Wauer et al. ‘‘species.’’ The courts concluded that, finding, that the significance of the 1993, p. 1076). once a determination is made that a portion of the range should be The best available scientific and species (i.e., species, subspecies, or determined based on its biological commercial information demonstrates DPS) meets the definition of contribution to the conservation of the that, despite the ongoing negative ‘‘endangered species’’ or ‘‘threatened species. For this reason, we describe the impacts to pygmy-owl habitat in the species,’’ it must be placed on the list threshold for ‘‘significant’’ in terms of eastern portion of its range, numbers in its entirety and the Act’s protections an increase in the risk of extinction for and densities have remained relatively applied consistently to all members of the species. We conclude that a high. Therefore, we find that listing an that species (subject to modification of biologically-based definition of eastern DPS of the overall pygmy-owl protections through special rules under ‘‘significant’’ best conforms to the population is not warranted under the sections 4(d) and 10(j) of the Act). purposes of the Act, is consistent with Act. Consistent with that interpretation, judicial interpretations, and best Significant Portion of the Range and for the purposes of this finding, we ensures species conservation. Thus, for interpret the phrase ‘‘significant portion the purposes of this finding, a portion The Act defines ‘‘endangered species’’ of its range’’ in the Act’s definitions of of the range of the pygmy-owl is as any species which is ‘‘in danger of ‘‘endangered species’’ and ‘‘threatened ‘‘significant’’ if its contribution to the extinction throughout all or a significant species’’ to provide an independent viability of the species is so important portion of its range,’’ and ‘‘threatened basis for listing; thus there are two that, without that portion, the pygmy- species’’ as any species which is ‘‘likely situations (or factual bases) under which owl would be in danger of extinction. to become an endangered species within a species would qualify for listing: A Therefore, if we determine that the the foreseeable future throughout all or species may be endangered or pygmy-owl is endangered or threatened a significant portion of its range.’’ The threatened throughout all of its range in a significant portion of its range, and definition of ‘‘species’’ is also relevant (which we have determined is not the it would be in danger of extinction in to this discussion. The Act defines the case with the pygmy-owl); or a species the rest of its range without that portion, term ‘‘species’’ as follows: ‘‘The term may be endangered or threatened in that portion is significant and we will ‘species’ includes any subspecies of fish only a significant portion of its range. If list the entire species according to its or wildlife or plants, and any distinct a species is in danger of extinction status there. population segment [DPS] of any throughout an SPR, the species is an We evaluate biological significance species of vertebrate fish or wildlife ‘‘endangered species.’’ The same based on the principles of conservation which interbreeds when mature.’’ The analysis applies to ‘‘threatened species.’’ biology using the concepts of phrase ‘‘significant portion of its range’’ Based primarily on existing case law, redundancy, resiliency, and (SPR) is not defined by the statute, and the consequence of finding that a representation. Resiliency describes the we have never explicitly addressed it in species is endangered or threatened in characteristics of a species that allow it our implementing regulations either: (1) only a significant portion of its range is to recover from periodic disturbance. The consequences of a determination that the entire species shall be listed as Redundancy (having multiple that a species is endangered or likely to endangered or threatened, respectively, populations distributed across the become so throughout a significant and the Act’s protections shall be landscape) may be needed to provide a portion of its range, but not throughout applied across the species’ entire range. margin of safety for the species to all of its range; or (2) what qualifies a We conclude, for the purposes of this withstand catastrophic events. portion of a range as ‘‘significant.’’ finding, that interpreting the SPR phrase Representation (the range of variation Two recent district court decisions as providing an independent basis for found in a species) ensures that the have addressed whether the SPR listing is the best interpretation of the species’ adaptive capabilities are language allows the Service to list or Act because it is consistent with the conserved. Redundancy, resiliency, and protect less than all members of a purposes and the plain meaning of the representation are not independent of

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each other, and some characteristic of a ‘‘significant’’ only if threats in that its range, and the threats it faces, it species or area may contribute to all portion result in the entire species being might be more efficient for us to address three. For example, distribution across a currently endangered or threatened. the significance question first or the wide variety of habitats is an indicator Such a high bar would not give the SPR status question first. Thus, if we of representation, but it may also phrase independent meaning, as the determine that a portion of the range is indicate a broad geographic distribution Ninth Circuit held in Defenders of not ‘‘significant,’’ we do not need to contributing to redundancy (decreasing Wildlife v. Norton, 258 F.3d 1136 (9th determine whether the species is the chance that any one event affects the Cir. 2001). endangered or threatened there; if we The definition of ‘‘significant’’ used in entire species), and the likelihood that determine that the species is not some habitat types are less susceptible this finding carefully balances these endangered or threatened in a portion of to certain threats, contributing to concerns. By setting a relatively high its range, we do not need to determine resiliency (the ability of the species to threshold, we minimize the degree to recover from disturbance). None of these which restrictions will be imposed or if that portion is ‘‘significant.’’ In concepts is intended to be mutually resources expended that do not practice, a key part of the portion status exclusive, and a portion of a species’ contribute substantially to species analysis is whether the threats are range may be determined to be conservation. But we have not set the geographically concentrated in some ‘‘significant’’ due to its contributions threshold so high that the phrase ‘‘in a way. If the threats to the species are under any one of these concepts. significant portion of its range’’ loses essentially uniform throughout its For the purposes of this finding, we independent meaning. Specifically, we range, no portion is likely to warrant determine if a portion’s biological have not set the threshold as high as it further individual consideration. contribution is so important that the was under the interpretation presented Moreover, if any concentration of portion qualifies as ‘‘significant’’ by by the Service in the Defenders threats applies only to portions of the asking whether, without that portion, litigation. Under that interpretation, the species’ range that clearly would not the representation, redundancy, or portion of the range would have to be meet the biologically-based definition of resiliency of the species would be so so important that current imperilment ‘‘significant,’’ such portions will not impaired that the species would have an there would mean that the species warrant further consideration. increased vulnerability to threats to the would be currently imperiled point that the overall species would be everywhere. Under the definition of Therefore, having determined that the in danger of extinction (i.e., would be ‘‘significant’’ used in this finding, the pygmy-owl does not meet the definition ‘‘endangered’’). Conversely, we would portion of the range need not rise to of a threatened or endangered species not consider the portion of the range at such an exceptionally high level of throughout its range or within any issue to be ‘‘significant’’ if there is biological significance. (We recognize considered DPS configuration, we next sufficient resiliency, redundancy, and that if the species is imperiled in a considered whether there are any representation elsewhere in the species’ portion that rises to that level of significant portions of the range where range that the species would not be in biological significance, then we should the pygmy-owl is in danger of extinction danger of extinction throughout its conclude that the species is in fact or is likely to become endangered in the range if the population in that portion imperiled throughout all of its range, foreseeable future. We engaged in a of the range in question became and that we would not need to rely on systematic process that began with extirpated (extinct locally). the SPR language for such a listing.) identifying any portions of the range of We recognize that this definition of Rather, under this interpretation we ask the pygmy-owl that may warrant further ‘‘significant’’ establishes a threshold whether the species would be consideration. that is relatively high. On the one hand, endangered everywhere without that given that the consequences of finding portion, i.e., if that portion were To determine whether any portions of a species to be endangered or threatened completely extirpated. In other words, the pygmy-owl’s range warranted in an SPR would be listing the species the portion of the range need not be so further consideration as possible throughout its entire range, it is important that even being in danger of threatened or endangered significant important to use a threshold for extinction in that portion would be portions of the range, we reviewed the ‘‘significant’’ that is robust. It would not sufficient to cause the remainder of the entire supporting record for the status be meaningful or appropriate to range to be endangered; rather, the review of this species with respect to establish a very low threshold whereby complete extirpation (in a hypothetical the geographic concentration of threats, a portion of the range can be considered future) of the species in that portion and the significance of portions of the ‘‘significant’’ even if only a negligible would be required to cause the range to the conservation of the species. increase in extinction risk would result remainder of the range to be We chose to first identify any portions from its loss. Because nearly any portion endangered. of the pygmy-owl’s range where the of a species’ range can be said to The range of a species can species may be in danger of extinction contribute some increment to a species’ theoretically be divided into portions in or likely to become so within the viability, use of such a low threshold an infinite number of ways. However, foreseeable future. We found that would require us to impose restrictions there is no purpose to analyzing documented and potential population and expend conservation resources portions of the range that have no declines are occurring in some parts of disproportionately to conservation reasonable potential to be significant benefit; listing would be rangewide, and threatened or endangered. To the pygmy-owl’s range, but not even if only a portion of the range of identify only those portions that warrant throughout the range of the pygmy-owl, minor conservation importance to the further consideration, we determine indicating the possibility that threats species is imperiled. On the other hand, whether there is substantial information affect the species to varying degrees it would be inappropriate to establish a indicating that: (1) The portions may be across the range of the pygmy-owl. threshold for ‘‘significant’’ that is too ‘‘significant,’’ and (2) the species may be Additionally, the best available data high. This would be the case if the in danger of extinction there or likely to indicates that the impacts identified standard were, for example, that a become so within the foreseeable future. above do not occur uniformly portion of the range can be considered Depending on the biology of the species, throughout the range of the pygmy-owl.

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Analysis of Potential Significant Pygmy-Owl Population Status Within areas of the State and occur in similar Portions of the Range the Sonoran Desert Ecoregion densities. Within the Mexico portion of the We identified one area of the pygmy- Within the Arizona portion of the Sonoran Desert Ecoregion, pygmy-owl owl’s range that warrants further Sonoran Desert Ecoregion, the pygmy- numbers are higher, but, similar to their consideration as a possible threatened owl occurs in very low numbers in distribution in Arizona, pygmy-owls or endangered significant portion of the widely scattered population groups also occur here as scattered population range. Based on our five-factor analysis within the State. Historically (i.e., late groups throughout the occupied area of threats throughout the range of the 1800s and early 1900s), pygmy-owls (Flesch 2003, pp. 123–124). Recent pygmy-owl, we found that the Sonoran occupied areas of south-central Arizona, surveys and research in northwestern Desert Ecoregion was an area where from New River, about 56 km (35 mi.) Mexico indicate that numbers and documented and potential declines in north of Phoenix, south to the United density of pygmy-owls are higher in pygmy-owl populations have occurred, States and Mexico border, west to Agua thornscrub and tropical deciduous indicating the species may be Caliente near Gila Bend and Cabeza forest communities of southern Sonora threatened or endangered there. Prieta Tanks, and east to Tucson, and, and Sinaloa than in the Sonoran rarely, the San Pedro River (Bent 1938, desertscrub and semi-desert grassland Sonoran Desert Ecoregion SPR Analysis pp. 435–438; Monson and Phillips 1981, vegetation communities of the Sonoran Desert Ecoregion (Flesch 2003, pp. 39– We identified the Sonoran Desert pp. 71–72; Johnson et al. 2003, pp. 390– 391). The geographic area historically 42; AGFD 2008a, p. 6). Long-term Ecoregion as a portion of the pygmy- monitoring of pygmy-owl sites in owl’s range that was potentially occupied by pygmy-owls in Arizona includes portions of Gila, Pima, Pinal, northern Sonora indicates that the significant, and that could potentially Maricopa, Graham, Santa Cruz, Cochise, extended drought has resulted in meet the criteria for threatened or Greenlee, and Yuma Counties. reduced occupancy at monitored sites endangered (Figure 3). The decision to Currently, the known locations of (Flesch 2008, pp. 4–5). Pygmy-owl use this area to define the boundaries of pygmy-owls in Arizona are restricted to survivorship is tied to precipitation that portion of the overall pygmy-owl two counties, Pima and Pinal (Service (Flesch 2008, pp. 5–6; Service 2004, p. range that may be significant was based 2011, p. 1; Service 2009b, p. 1; Abbate 1). As in Arizona, drought has on factors related to pygmy-owl ecology et al. 2000, pp. 15–16). The current negatively affected the numbers and and information available related to the distribution of pygmy-owls within distribution of pygmy-owls on the status of the pygmy-owl. This portion of Arizona is significantly reduced from its landscape within the analysis area the pygmy-owl’s range is characterized historical distribution. (Flesch 2008, pp. 5–6). While data by a generally unique vegetation adequate to define population trends in community. The Sonoran Desert has the Historically, the pygmy-owl was Sonora, Mexico, are lacking, field data greatest diversity and vegetative growth found as far north as New River in indicate that pygmy-owls in the of any desert worldwide. It is the most Maricopa County, and, prior to the mid- southern portions of the State (within tropical of the three North American 1900s, early naturalists considered the thornscrub and tropical deciduous warm deserts (Sonoran, Mojave, and pygmy-owl ‘‘not uncommon,’’ ‘‘of forests) are common and likely number Chihuahuan) (Williams et al. 2001, pp. common occurrence,’’ and a ‘‘fairly on the order of thousands, while further 1–2; MacMahon and Wagner 1985, pp. numerous’’ resident of the areas in north within the Sonoran Desert 105–202). The boundaries of this which they traveled in Arizona Ecoregion, they are fewer in number, vegetation community have been (Breninger 1898, p. 28; Gilman 1909, p. more patchily distributed, and likely consistently described in a number of 148; Swarth 1914, p. 31). Recent data number on the order of hundreds indicate that there are fewer than 50 papers (Marshall et al. 2000, pp. 4–7; (Flesch 2003, pp. 39–42; AGFD 2008a, adult pygmy-owls and fewer than 10 McLaughlin and Bowers 1999, pp. 3–7; p. 6). nest sites in Arizona in any given year Dimmitt 2000, pp. 13–15; Brown 1994, (Abbate et al. 2000, pp. 15–16). Limited Significance of the Sonoran Desert p. 181; Leopold 1950, p. 513; Shreve surveys and monitoring conducted in Ecoregion 1951, pp. 1–3; and Nabhan and 2009 indicate that pygmy-owls in Holdsworth 1998, pp. 1–5). Finally, This part of the pygmy-owl’s range Arizona still occupy the areas of Avra number and density estimates from contains habitat that meet the needs of Valley, Altar Valley, and Organ Pipe the pygmy-owl for reproduction and formal studies and incidental Cactus National Monument (Service survival, and can support self-sustaining observations from the field show that 2009b, p. 1; 2011, p. 1). However, population groups. It also provides a this area has markedly lower numbers populations of pygmy-owls in Arizona mosaic of connected habitat maintaining and densities of pygmy-owls than the are in an ongoing decline (AGFD 2008a, dispersal and genetic exchange among other areas of its range, and that p. 2). Comprehensive surveys have not subpopulations. The habitat found in population declines have occurred been conducted on the Tohono this portion of the range may become within the area (AGFD 2008a, p. 2; O’odham Nation in Arizona. A number increasingly important if the predictions Flesch and Steidl 2006, p. 869). of surveys have been completed on the about climate change prove correct. As For the purposes of this analysis, the Nation with respect to various utility hotter, drier conditions prevail, this current range of the pygmy-owl within and roadway projects, and some of these area, which already provides habitat the Sonoran Desert Ecoregion includes surveys did document the presence of under these conditions, may provide the those areas of the ecoregion within the pygmy-owl. But distribution of the data largest, most contiguous blocks of Arizona Counties of Pima and Pinal, from these surveys has been restricted higher quality habitat if the wetter, more and the Mexican State of Sonora, from by the Nation and is not readily tropical habitats (thornscrub and the area immediately south of the available for analysis. There are large tropical deciduous forests) are reduced western border of Pima County, east to areas of suitable habitat on the Nation, due to climate change. Conditions in the Nogales, and south from Nogales to but the information we have indicates Sonoran desert are also likely to become Guaymas and then back northwest to that pygmy-owls are patchily hotter and drier. However, the the western coast of Sonora. distributed in those areas as in other population groups of pygmy-owls found

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in the Sonoran Desert Ecoregion are of the range is different genetically than the pygmy-owl’s status such that these already adapted to the drier climate that the remainder of the range. Proudfoot DPSs warrant listing under the Act. is likely to become more widespread (2006a, p. 7) indicates that pygmy-owls However, because we found that these under current climate change scenarios in this portion of the range share no DPS configurations were appropriate and, therefore, this shift in temperature haplotypes with populations in Texas or under our DPS policy, we next and precipitation may have a reduced in the remainder of Mexico. Using evaluated whether the Sonoran Desert effect on pygmy-owls in this area. information in Proudfoot et al. (2006a, Ecoregion represents significant Saguaros and other columnar cacti may pp. 6–9 and 2006b, pp. 5–7), we have portions of the western and eastern experience range-shifts associated with determined that the Arizona/Sonora DPSs respectively. climate change, however, there is much pygmy-owls contribute approximately Potential Sonoran Desert Ecoregion SPR uncertainty associated with the current 10 percent of the species total of the Western DPS models of individual species responses mitochondrial DNA (mtDNA) variation to climate change. Therefore, and 5 percent of the total alleles (gene The portion of the Sonoran Desert predictions about the decline of types) detected in their study (Service Ecoregion currently occupied by pygmy- columnar cacti are too speculative to 2009c, p. 1). This data analysis indicates owls represents approximately 33 consider in this finding. This that this part of the range does have percent of the Western DPS (Figure 3). population group of pygmy-owls is unique alleles and contributes to the Even though this is only approximately likely to become a more significant genetic variation within the range of the one-third of the Western DPS, this contributor to the long-term viability of pygmy-owl. There is evidence of portion of the DPS may provide this species. restricted gene flow between the important contributions to population Given the presumed adaptation of this Arizona/western Mexico and Texas/ numbers, genetic diversity, and status of segment of the population to drier, more eastern Mexico populations (Cicero the pygmy-owls within this DPS. extreme conditions, we considered 2008, p. 2; Oyler-McCance 2008, pp. 1– In considering the portion of the whether the demographic characteristics 2; Dumbacher 2008, p. 9). western DPS outside of the Sonoran of this population might be important We have found that the Sonoran Desert Ecoregion and whether it may be for the species to recover from predicted Desert Ecoregion has unique habitat in danger of extinction, we find it is changes in the ecosystem due to climate characteristics and the pygmy-owls in likely that the population of pygmy- change. Although birds in every this area possess some unique owls in this area is large enough to terrestrial habitat will be affected by behavioral and genetic adaptations to withstand environmental catastrophes climate change, birds in arid lands show this area. Next, we evaluated whether, and random perturbations. This is lower overall vulnerability to the effects should this portion of the range because the area outside of the Sonoran of climate change (NABCI 2010). theoretically be extirpated, the Desert Ecoregion represents Pygmy-owls in the Sonoran Desert remaining portion of the pygmy-owl’s approximately 67 percent of the DPS, Ecoregion may be more likely to be able current range would be in danger of and it likely supports a higher to provide population support for the extinction. This evaluation focused on proportion of the overall population remainder of its range. Therefore, the pygmy-owl’s rangewide population than the Sonoran Desert Ecoregion, demographic characteristics and status and the importance of this part of because this portion of the DPS is population size within this portion of the range to the entire range. characterized by thornscrub and tropical the range might allow for at least partial There is general consensus in the deciduous forest communities, which recovery of pygmy-owl populations literature and other reports that pygmy- have been documented to support within this portion of the range owls remain common throughout most higher numbers and densities of pygmy- following disturbance events. of the areas of Mexico south of Sonora owls than Sonoran desertscrub Pygmy-owls are secondary cavity and Texas. As noted above, the communities (Swarth 1914, p. 31; nesters, using cavities excavated in trees population of pygmy-owls in this Karalus and Eckert 1974, p. 218; and cacti. Within the Sonoran Desert ecoregion is small and scattered, and Monson and Phillips 1981, pp. 71–72; Ecoregion, pygmy-owls typically nest in thus represents only a small portion of Johnsgard 1988, Enriquez-Rocha et al. large, columnar cacti found throughout the overall pygmy-owl population. The 1993, p. 158; Proudfoot 1996, p. 75; the area. The Sonoran Desert Ecoregion best available information does not Proudfoot and Johnson 2000, p. 5). The contains the greatest concentration of indicate that, under the theoretical production and population growth of large columnar cacti (saguaro, organ removal of the Sonoran Desert the pygmy-owls outside the Sonoran pipe, hecho) anywhere in the range of Ecoregion from the current range of the Desert Ecoregion are likely high enough the pygmy-owl. While other areas to the pygmy-owl, the remaining portion of the to maintain viability of the population south of this portion of the range also range is likely to become extinct. under current conditions. Because the contain large, columnar cacti, they do Therefore, we do not find the Sonoran Sonoran Desert Ecoregion occurs at the not occur in as high of densities, nor are Desert Ecoregion of the pygmy-owl to be northern end of the Western DPS, the they as extensively distributed. In other significant, and thus it is not an SPR. theoretical loss of that portion would portions of its range, the pygmy-owl not result in fragmentation of the DPS nests in tree cavities; therefore, this Sonoran Desert Ecoregion SPR Analyses in a way that would affect movements aspect of the pygmy-owl’s life history in Relation to the Eastern and Western and connectivity of the pygmy-owl requirements is not exclusive to DPS’s population. columnar cacti, but it is an important We determined that the eastern and However, the theoretical loss of a and necessary element in this part of its western portions of the pygmy-owl’s third of the range might represent a range because nesting in saguaros current range represent DPSs; that is, we significant loss of important habitat and reduces the impacts to eggs and found that they are discrete and genetic diversity, affecting the nestlings from the temperature extremes significant to the taxon as a whole (see redundancy and representation of the and predation found in this portion of DPS discussion above). We found that overall pygmy-owl population, and the range. the best scientific and commercial possibly affect the remaining portion of There is some information indicating information did not indicate that the the population by reducing that this subdivision of the western part negative impacts in these DPSs affect metapopulation support including

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genetic adaptation and demographic the pygmy-owl is somewhat of a habitat pygmy-owl populations in the rescue. The current genetic structure of generalist and, if impacts to habitat foreseeable future. the western DPS indicates that there is occur over an extended period of time, We acknowledge that the Sonoran population movement within the DPS these populations may still be able to Desert Ecoregion represents an and, as a consequence, exchange of adapt to environmental changes in this important portion of the Western DPS, genetic material among population DPS. and of the taxon as a whole. However, groups, even though the distribution of The primary vegetation communities in order to find that the portion of the pygmy-owls on the landscape is patchy. found outside of the Sonoran Desert western DPS in the Sonoran Desert Removal of approximately 33 percent of Ecoregion in the Western DPS, Ecoregion is significant under our SPR the DPS might reduce the viability and thornscrub and subtropical dry forests, policy, our position is that its potential for long-term survival of the are under significant stress. As contribution to the viability of the remaining portion of the DPS. For discussed above, thornscrub and species must be so important that, example, the Sonoran Desert Ecoregion subtropical dry forests are among the without that portion, the pygmy-owl supports the portion of the DPS most threatened vegetation communities would be in danger of extinction. As population that is adapted to the unique in Mexico. Loss of dry tropical forest noted above in the discussion under environment of the Sonoran Desert. Loss occurs on as great, or greater, scale than Sonoran Desert Ecoregion SPR Analysis, of this segment of the population might the loss of tropical rain forests (Trejo even though pygmy-owls in this area substantially decrease the genetic and Dirzo 2000, p. 133). Only possess some unique behavioral and diversity of the overall DPS to the point approximately two percent of the genetic adaptations, the population of that the pygmy-owl may not be able to original distribution of subtropical dry pygmy-owls in this ecoregion is small adapt to what may be the predominant forests remains in Mesoamerica, and scattered, and thus represents only vegetation community under the including Mexico. Some areas of intact a small portion of the overall pygmy- predicted effects of climate change. dry tropical forest remain on steep owl population. The best available However, the thornscrub and tropical slopes within the western DPS (Allnutt information does not indicate that, if the deciduous forest communities have 2001, p. 3; Lugo 1999, p. 4). However, Sonoran Desert Ecoregion portion of the already been substantially reduced, and the topography of such slopes, above pygmy-owl’s range is extirpated, the this reduction and fragmentation is 1,200 m (4,000), renders these areas remaining portion of the Western DPS is likely to continue. Sonoran desertscrub unsuitable for occupancy by pygmy- likely to become extinct. Therefore, we will likely expand to the north and owls. In areas occupied by pygmy-owls, do not find the Sonoran Desert south as climates to the north become dry tropical forests are threatened by Ecoregion of the pygmy-owl to be warmer and climates to the south woodcutting, clearing for agriculture, significant, and thus it is not an SPR. become drier (Weiss and Overpeck urbanization, and impacts from invasive SPR Conclusion 2005, p. 2074). species. Urbanization is increasing, Pygmy-owl adaptations documented particularly in the southern portion of In summary, we have thoroughly in the Sonoran Desert Ecoregion include the Western DPS (Lugo 1999, p. 2; Trejo analyzed all potentially-listable entities the use of saguaro cavities as nest sites, and Dirzo 2000, p. 133). In Mexico of the pygmy-owl. For the reasons paler plumage coloration, ability to specifically, only approximately 27 described above, we find that the obtain moisture from prey rather than percent of the original cover of pygmy-owl is not in danger of free-standing water, and the ability to extinction now, nor is it likely to select nest locations that maintain seasonally dry forest remains intact (Trejo and Dirzo 2000, p. 139). become endangered within the productivity during drought conditions foreseeable future, throughout all or any In addition, increasing temperatures (AGFD 2008a, pp. 1–2 and b, pp. 3–7; significant portion of its range. due to climate change pose a serious Flesch 2008, p. 3; Flesch and Steidl Therefore, listing the pygmy-owl as threat to subtropical dry forests due to 2010, p. 1021). The ability of the endangered or threatened under the Act the transitional nature of the western DPS to adapt to impacts from is not warranted at this time. climate change may be substantially community, and the narrow temperature We request that you submit any new reduced with the theoretical loss of the and precipitation requirements of many information concerning the status of, or Sonoran Desert Ecoregion. of its native species (Allnutt 2001, p. 4). threats to, the pygmy-owl to our Arizona The Sonoran Desert Ecoregion Trejo and Dirzo (2000, p. 140) predicted Ecological Services Office (see population is characterized by lower that, under current rates of ADDRESSES) whenever it becomes numbers and density of pygmy-owls. deforestation, by the year 2030, intact available. New information will help us This is likely the result of reduced seasonally dry forests would be reduced monitor the pygmy-owl and encourage habitat quality and location of this to 10 percent of their original area. management of this subspecies and its population group at the northern extent Additionally, the remaining 10 percent habitat. If an emergency situation of the Western DPS. While this would likely be characterized by small, develops for the pygmy-owl or any other population may be considered marginal, vegetation islands separated from each species, we will act to provide it is important to recognize that other, causing significant ecological immediate protection. marginal populations may have a high repercussions at the genetic, ecological, adaptive significance to the species as a and ecosystem function levels of the References Cited whole, and marginal habitat ecoregion. Protected areas in Mexico A complete list of all references cited conservation, preservation and that include seasonally dry forests are in this document is available on the management is one of the best ways to few and total less than 10 percent of the Internet at http://www.regulations.gov conserve genetic diversity and resources remaining, intact forest areas in Mexico and upon request from the Arizona (Scudder 1989, p. 1). The portion of the (Trejo and Dirzo 2000, p. 140). This loss Ecological Services Office (see western DPS outside of the Sonoran and fragmentation of habitat, and the ADDRESSES). Desert Ecoregion may lack sufficient influence of climate change on the resiliency to meet future environmental remaining areas of native habitat, may Authors changes that are already manifesting substantially reduce the availability of The primary authors of this notice are themselves within this DPS. However, pygmy-owl habitat and, consequently, the staff members of the Arizona

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Ecological Services Office (see FOR Authority Dated: September 27, 2011. FURTHER INFORMATION CONTACT). The authority for this action is section Rowan W. Gould, 4 of the Endangered Species Act of Acting Director, U.S. Fish and Wildlife 1973, as amended (16 U.S.C. 1531 et Service. seq.). [FR Doc. 2011–25565 Filed 10–4–11; 8:45 am] BILLING CODE 4310–55–P

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