The Center for Biological Diversity submits the following information for the status review of the foothill yellow-legged frog (Rana boylii) (Docket #FWS-R8-ES-2015-0050), including substantial new information regarding the species' biology, population structure (including potential Distinct Population Segments of the species), historical and recent distribution and status, population trends, documented range contraction, habitat requirements, threats to the species and its habitat, disease, and the potential effects of climate change on the species and its habitat. The foothill yellow-legged frog has experienced extensive population declines throughout its range and a significant range contraction. Multiple threats continue unabated throughout much of the species’ remaining range, including impacts from dams, water development, water diversions, timber harvest, mining, marijuana cultivation, livestock grazing, roads and urbanization, recreation, climate change and UV-radiation, pollution, invasive species and disease. The species warrants listing as threatened under the Endangered Species Act. Contact: Jeff Miller, [email protected] Contents: NATURAL HISTORY, BIOLOGY AND STATUS . .. 2 Biology. .2 Habitat . .. .4 Range and Documented Range Contraction . 4 Taxonomy . 9 Population Structure . 9 Historical and Recent Distribution and Status . 15 Central Oregon . .15 Southern Oregon . 18 Coastal Oregon . .20 Northern Coastal California . 25 Upper Sacramento River . 40 Marin/Sonoma . 45 Northern/Central Sierra Nevada . .47 Southern Sierra Nevada . .67 Central Coast/Bay Area . 77 South Coast. 91 Southern California . .. 94 Baja California, Mexico . .98 Unknown Population Affiliation. .99 Population Trends . .. .103 THREATS. .108 Habitat Alteration and Destruction . .. 108 Dams, Water Development and Diversions . .. .109 Logging . .. .111 Marijuana Cultivation . .. .112 Livestock Grazing . .. .112 Mining . .. .. .113 Roads and Urbanization . .. 114 Recreation . .. .. 114 Off-road Vehicles . .. 114 Inadequacy of Existing Regulatory Mechanisms . .. .115 Other Factors . 121 Climate Change and UV-Radiation . .. .121 Pollution . .. 123 Invasive Species . .. .125 Disease . .. .126 Conclusion . .. .. .. .128 LITERATURE CITED. .129 1 NATURAL HISTORY, BIOLOGY, AND STATUS Biology Foothill yellow-legged frogs are small ranid frogs with snout-urostyle lengths ranging from approximately 1.5 to 2 centimeters (cm) at metamorphosis to 6 to 8 cm for adults, with females growing to larger sizes than males. The life cycle is synchronized with the seasonal timing of streamflow condition. Radiotelemetry studies show that adult frogs move throughout dendritic networks of streams from winter refugia where they can avoid mortality due to flooding (Bourque 2008; Gonsolin 2010) to mating habitat where eggs are laid in spring and tadpoles rear in summer (Wheeler and Welsh 2008). Non-breeding habitat is characterized by perennial water where they can forage through the summer and fall months. Breeding is triggered by warming water temperatures, decreasing streamflows, and increasing daylength during the transition between the wet and dry season. Breeding sites are generally (but not always) located in low-gradient stream reaches at depositional features such as lateral point bars and pool tail-outs (Kupferberg 1996; Wheeler and Welsh 2008). Breeding may commence as early as March in warm coastal locations and as late as July in snowmelt dominated rivers (Storer 1925; Zweifel 1955; Ashton et al. 1998; AmphibiaWeb 2012; Wheeler et al. 2014). Like most ranid frogs, males probably defend areas around themselves during breeding season (Martof 1953; Emlen 1968). Foothill yellow-legged frog vocalizations are seldom heard. The voice is a gutteral, grating sound on one pitch or with rising inflection, a single croak lasting ½ to ¾ of a second. Four or five croaks may be given in rapid series followed by a rattling sound, the entire sequence lasting about 2.5 seconds (Stebbins 1985). While much of the mate calling occurs underwater (MacTague and Northern 1993), males also call from above water. Above water calls are faint and are not generally heard over distances greater than 50 meters (Ashton et al. 1998). Examples of both above water, and underwater calls are documented and described on Frog and Toad Calls of the Pacific Coast (Davidson 1995). Females oviposit eggs in shallow water toward the margin of streams, attached to sides of stones in the stream bed (Kupferberg 1996). Cobble and pebble are the preferred substrate for egg mass attachment, but egg masses have been found attached to aquatic vegetation, woody debris, and gravel (Fuller and Lind 1992; Ashton et al. 1998). Females lay a distinct cluster of eggs, with average clutch sizes ranging from 100 to 1,100 eggs (Storer 1925; Wright and Wright 1949). Eggs hatch in 5 to 30 days, or more (Zweifel 1955). In the mainstem Trinity River, eggs hatch in 27 to 36 days (Ashton et al. 1998). The slower development is probably due to colder temperatures from dam released water. At the time of hatching, the embryos are at a Gosner stage of 20 to 22 (Ashton et al. 1998). In the absence of disturbance, the tadpoles will remain associated with the egg mass for several days after hatching then disperse to local interstices of the gravel bed, often moving downstream in areas of moderate flow (Ashton et al. 1998). Larval growth rate is dependent on water temperature (Duellman and Trueb 1986), but metamorphosis generally occurs in three to four months. Foothill yellow-legged frogs usually reach sexual maturity at age 1 to 2 2 years, at a length of about 40 mm (Zweifel 1955), although some individuals may reproduce as early as 6 months after metamorphosis (Jennings 1988). Rana boylii tadpoles feed on algae scraped from rocks or plants. They seem to grow fastest feeding on epiphytic diatoms and have been observed to preferentially graze on this algal type (Jennings and Hayes 1994; Ashton et al. 1998). Tadpoles have been observed actively congregating on dead tadpoles and dead, open bivalves (Ashton et al. 1998). Metamorphosed frogs feed primarily on terrestrial invertebrates, but also eat some aquatic invertebrates (Fitch 1936; Zeiner et al. 1988). Adult diet includes flies, moths, mosquitoes, hornets, ants, beetles, grasshoppers, water striders, and snails (Fitch 1936; Nussbaum 1983; Csuti et al. 2001). Van Wagner (1996) provided a thorough literature review and a detailed diet analysis of post-metamorphic R. boylii. Analysis of 63 post-metamorphic R. boylii found terrestrial arthropods to be the primary (~90%) prey items year round, comprised of 87.5% insects and 12.6% arachnids (Van Wagner 1996). Foothill yellow-legged frogs capture their prey by waiting along stream edges and pouncing (Airola 1980). The foothill yellow-legged frog is primarily diurnal and is active year-round, with peak activity in April and May (Airola 1980). Home ranges and dispersal patterns of the foothill yellow-legged frog are poorly understood (Jennings and Hayes 1994). Frogs have been found 50 m (Nussbaum et al. 1983; Csuti et al. 2001) to 70-80 m (C. Rombough, pers. comm., as cited in Olson and Davis 2009) from water. Along streams, Van Wagner (1996) reported seasonal movements of about 450 m for this species in California, and an 800 m movement distance is known from Oregon (C. Rombough, pers. comm., as cited in Olson and Davis 2009). A telemetry study by Bourque (2008) in Tehama County, California documented movement distances of 0.65 km and 7.04 km for male and female foothill yellow-legged frogs, respectively, and median travel distances of 65.7 and 70.7 meters/day. Frogs used watercourses as movement corridors and rarely moved > 12 m from the stream channel. During breeding season and summer, foothill yellow-legged frogs are rarely encountered far from permanent water. Adults congregate around breeding pools in April, May, and June. In late summer adults were found to be scarce along the main stem of the Trinity River, indicating that they may be dispersing into the vegetation, moving up tributaries, or reducing diurnal activity (Ashton et al. 1998). Recently metamorphosed frogs show a strong tendency to migrate upstream (Twitty 1967). This may be an evolutionary mechanism to repatriate individuals washed downstream from suitable habitat during the larval stage. During the winter, frogs have been observed in abandoned rodent burrows and under logs as far as 100 m from streams (Zeiner et al. 1988; Welsh 1994). Movements of marked animals were not noted to occur November through March in Oregon (C. Rombough, pers. comm., as cited in Olson and Davis 2009). Radio telemetry tracking of postbreeding adult females in California documented dispersal distances from 0 to 7,043 m (R. Bourque, pers. comm., as cited in Olson and Davis 2009) where, over the course of 60 days, one female traveled upstream along the main channel of a perennial stream, then up intermittent and dry tributary channels, then over a ridge eventually working her way downstream to perennial waters in an adjacent watershed (R. Bourque, pers. comm., as cited in Olson and Davis 2009). Other ranids have capabilities of dispersing kilometers overland; however, according to Nussbaum et al. 3 (1983) this species is likely restricted to movements along streams or stream-riparian corridors. Their likely restriction to riparian corridors needs further study because of the low detectability of frogs in uplands. Dever’s (2007) genetic study suggested that a distance of 10 km