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FINAL REPORT ______________________________________________________________________________________ ANALYSIS SPECIES ASSESSMENT: Red-legged Frog (Rana aurora aurora) RELICENSE STUDY T-4 ______________________________________________________ FERC PROJECT NO. 2150 Prepared by: 19997 Hwy 9 Mount Vernon, WA 98274 Phone: (360) 422-6510 Prepared for: Puget Sound Energy Baker River Project Relicense Wildlife and Terrestrial Resources Working Group February 21, 2003 ______________________________________________________________________________________ Unpublished Work © 2003, Puget Sound Energy, Inc. Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 Baker River Terrestrial Working Group Analysis Species Red-legged Frog (Rana aurora aurora) Drafted by Danielle Flath, Sarie Nichol and Frank Lapsansky Habitat Type: Wetland/Riparian Species Species Biology and Population Status: • • • • • • • • • • • The red-legged frog (Rana aurora) is a medium to large sized frog found west of the coastal mountain ranges of western North America from Southern British Columbia to the northern Baja Peninsula of California (Green and Campbell 1984). The northern subspecies, R. aurora aurora occurs from southwestern British Columbia, through Washington and Oregon and into northern California, where it intergrades with the California subspecies (R. aurora draytonii) in Mendocino County, California (Nussbaum et al. 1983, Hayes and Miyamoto 1984). Adult females typically measure approximately 100 mm (3.9 inches) snout-to-vent length, while males are considerably smaller, measuring around 70 mm (2.8 inches) snout-to-vent length (Nussbaum et al. 1983). Eggs are in a soft grapefruit to cantaloupe- sized mass and may be laid close together but not on top of each other (Corkran and Thomas 1996). The egg mass is generally 15 to 25 cm (0.6 to 1.0 inches) in diameter, and contains 500 to 1,100 eggs (Nussbaum et al. 1983). A unique identifying characteristic of the red-legged frog is coloration of the hind leg underside. It is translucent red in adults and pale pink in juveniles (Corkran and Thomas 1996). R. aurora can be found in elevations ranging from sea level to 920 meters (3,000 ft) (Corkran and Thomas 1996). R. aurora is a forest dwelling frog that frequents small ponds, quiet pools along streams, springs, lakes, reservoirs and swamps in sheltered, damp forests (Nussbaum et al. 1983, Green and Campbell 1984). R. aurora is dependant on water for breeding while adults are semi-aquatic to terrestrial (Gomez and Anthony 1996; Kiesecker and Blaustein 1998). In the state of Washington, R. aurora has been documented in the three following Physiographic Provinces: Olympic Peninsula and Southwestern Washington, the Puget Trough, and Western Slopes and Crests Washington Cascades (Corkran and Thomas 1996). There are conflicting reports of territoriality among red-legged frogs. While some authors have never observed territorial behavior in R. aurora others have observed male exclusion from breeding (Calef 1973, Nussbaum et al. 1983). R. aurora is typically found sitting on the banks of ponds etc., during the day, however, when predators approach it jumps into water and may remain there for long Unpublished Works © 2003, Puget Sound Energy, Inc. Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 • • • • periods of time (Gregory 1979, Licht 1986). Red-legged frogs are also encountered along forest trails near damp valley bottoms (Green and Campbell 1984). Predation is the main cause of mortality of R. aurora in all stages of development. Predators of adult and larvae R. aurora include; garter snakes, northwestern salamanders, bullfrogs, roughskin newts, cutthroat trout, great blue herons, belted kingfishers, red-tailed hawks, marsh hawks, hooded mergansers, great horned owls, raccoons, red foxes, striped skunks, minks, and feral housecats. Predators of larvae R. aurora include; giant water bugs, backswimmers, Dytiscid beetles, water scorpions, and odonate nymphs (Licht 1974). A study of R. aurora survivorship in British Columbia estimated 5% of eggs laid reached metamorphosis. After one season 2.5% of individuals survived and survival from eggs to sexual maturity was less than 1%. Rate of survival in adults was significantly higher at 69% (Licht 1974). Although no long-term population studies of R. aurora have been conducted, observations suggest that numbers are dwindling in areas outside of old-growth habitat (Blaustein et al. 1995). R. aurora aurora is neither a state-listed nor a state-candidate for listing, and it is not a species of concern by priority habitat type in Washington State (WDFW 1997). Nesting/Reproductive Behavior: • • • • • R. aurora breeds during winter (January to March) in western valleys and coastal areas of Oregon and Washington. Movement to breeding sites is temperature dependent, and males are first to arrive at breeding waters. In Corvallis, Oregon, frogs migrate to breeding areas when air temperatures reach 10° C (50° F) (typically in January). R. aurora has the lowest known temperature tolerance of any North American ranid embryo (Licht 1969, 1971, Nussbaum et al. 1983). Egg masses are often deposited at night near the water surface, attached to the stems of submerged vegetation (Nussbaum et al. 1983, Belden and Blaustein 2002). Time of egg-laying is temperature dependent, generally occurring in February and early March in northwestern Washington, at water temperatures of at least 6° C (43° F) (Nussbaum et al. 1983). Hatching time is dependent on temperature; embryos develop faster in warmer water. In northwestern Washington, embryos reach the gill circulation stage (stage 20 of 21 in embryo development) in about 35 days (Licht 1971). In the Puget lowlands, red-legged frogs oviposit in early March, and larvae begin metamorphosis in late July (Adams 1999). Time of metamorphosis and size at metamorphosis is dependent on environmental conditions and varies throughout its range (i.e. R. aurora was 28.7 mm [1.1 inches], 20-25 mm [0.8-1.0 inches], and 22 mm [0.9 inches] at metamorphosis in Washington (Brown 1975), Oregon (Storm 1960), and British Columbia (Calef 1973), respectively). Compared with other ranids, time to metamorphosis is long (Brown 1975). R. aurora reach sexual maturity in their second year after metamorphosis when females measure about 60 mm (2.4 inches) snout-to-vent length and males reach 50 Unpublished Works © 2003, Puget Sound Energy, Inc. 2 Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 • mm (2.0 inches) snout-to-vent length. Limited evidence suggests that males and females breed every year (Nussbaum et al. 1983). Some males are polygynous within a single season (Nussbaum et al. 1983). Habitat Requirements: • • • • • • • • • The red-legged frog is the most forest-associated anuran in Washington (Corkran and Thomas 1996). R. aurora breeds in relatively still waters shaded by overhanging vegetation (Corkran and Thomas 1996); small, shallow, temporary ponds, large lakes (i.e. Marion Lake in British Columbia which is a 13 ha [32 ac] permanent lake), in potholes, in the overflows of rivers and lakes, and in the slow-moving portions of rivers (Nussbaum et al. 1983). Emergent vegetation that is linear in structure (i.e. willow branches, cattails, weed branches, grasses) is characteristic of these habitats (Blaustein et al. 1995). Within Washington State, R. auroras are most abundant in seasonally flooded areas attached to permanent wetlands and seasonally flooded areas that hold water through late July (Adams 1999). Shallow water and emergent vegetation are essential for growth and development as these parameters result in warmer temperatures and increased algal productivity (Kiesecker et al. 2001). Adults appear to favor riparian areas located in mature stands rather than upslope habitat or younger stands of trees (Aubry and Hall 1991, Gomez and Anthony 1996). R. aurora is most common at sites with a shallow slope and southerly aspect (Adams 1999). A study conducted by Aubry and Hall (1991) in southwestern Washington, found R. aurora to be negatively associated with elevation, slope, talus, and rocky outcrops and positively associated with all deciduous and broadleaved evergreen trees. R. aurora was also highly associated with woody debris but not necessarily with stand age, which may indicate the importance of woody debris for providing hiding cover. Amphibian richness is associated with hydrology, vegetative diversity and the presence of exotic fishes. In many areas of the Pacific Northwest human activities have altered hydrology and are transforming many temporary wetlands that historically dried up during summer into wetlands with permanent standing water year-round. Changes in habitat structure and composition associated with altering hydrology affect ecosystem productivity, native predator communities, and native species’ vulnerability to exotic predators and competing species. Although the redlegged frog is most abundant in seasonally flooded areas associated with permanent standing water, and in temporary wetlands where standing water remains well into the summer, the loss of shallow emergent marsh may be detrimental. These changes may also be detrimental for many other aquatic and semi-aquatic species specialized to temporary wetland environments (Adams 1999). It is not uncommon for red-legged frogs to move distances greater than 1 km between riparian breeding sites and upland forests during the post-breeding season. In the Unpublished Works © 2003, Puget Sound Energy, Inc. 3 Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 south Umpqua basin of southwestern Oregon, a PIT-tagged adult female was found 2.4 km (1.5 mi) from its breeding pond almost 5 months after its initial capture (note: the author states that this may still not represent the maximum distance traveled during an active season). PIT-tagged adult males were also recaptured at distances ranging from 1.1-1.3 km (0.7-0.8 mi) from their breeding pond (Hayes et al. 2001). Food Resources and Foraging Behavior: • • • • • • R. aurora are diurnal foragers, however, they may feed at night during warm weather (Licht 1986). R. aurora feed predominantly on land; along river margins and amongst the surrounding vegetation (Licht 1986). Both adult and juvenile R. aurora are quite secretive and as a result their feeding behavior has rarely been documented in the field. Newly transformed red-legged frogs are relatively conspicuous and are often observed along river banks following metamorphosis. On warm dry summer days, young R. aurora feed at the water margin, catching small insects along the banks, in the vegetation and occasionally swimming a few centimeters into the water to prey on insects on the water surface or on aquatic plants. During early morning, when moisture collects on vegetation, small R. aurora can be found feeding in the undergrowth. During or after a rain, R. aurora will often move further from their water source. R. aurora is often found along the margins of rainpools catching small prey in and out of the water (Licht 1986). Prey size increases with age and size of the frog, and includes a wide variety of insects, arachnids and mollusks (Blaustein et al. 1995). Red-legged frogs eat beetles, caterpillars, isopods, and other small invertebrates (Nussbaum et al. 1983). A red-legged frog was found with a live Columbia Torrent Salamander in its mouth in September of 2000 in the Stillman Basin, Lewis County, in southwestern Washington. This marks the first documented case of R. aurora taking vertebrate prey (Rabinowe et al. 2002). Responses to Habitat Alteration and Effects of Human Activity: • Conversion of large, complex wetland areas and temporary ponds to permanent ponds causes several problems for the R. aurora: o Permanent ponds lack extensive emergent vegetation essential to R. aurora survival (Kiesecker et al. 2001). o Conversion of complex wetlands to permanent ponds has been implicated in the spread and success of predatory exotics such as bullfrogs and several fish species all of which require permanent water for over-wintering (Adams 2000; Kiesecker et al. 2001). Unpublished Works © 2003, Puget Sound Energy, Inc. 4 Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 • • • • o Permanent ponds increase clumping of the emergent vegetation that is present resulting in competition for food resources (Kiesecker et al. 2001). o Shallow water areas are typically of higher temperature and of higher algal growth, both of which are beneficial to R. aurora development (Kiesecker et al. 2001). The following species have been recorded as having significant impact on R. aurora populations: o Bull frog; although the occurrence of red-legged frogs in the Puget lowlands is more closely associated with habitat structure and the presence of exotic fish than bullfrogs (Adams 1999; Cook and Jennings 2001; Kiesecker and Blaustein 1998; Keisecker et al. 2001) o Small mouth bass (Adams 1999; Kiesecker and Blaustein 1998). o Native newts (Gomez and Anthony 1996) While sub-lethal, current levels of UV-B light are effecting development of R. aurora as stratospheric ozone depletion has lead to increased ambient UVB (Belden and Blaustein 2002). Acidification of lakes and ponds decreases amounts of dissolved organic carbons in the water resulting in increased water column penetration by UV-B (Belden and Blaustein 2002). Under laboratory conditions, R. aurora tadpoles exposed to relatively high concentrations of the herbicide Diuron (>7.6 mg/L for 14 days) experienced delayed hindlimb bud and forelimb development. Although field studies are needed to determine the effects of Diuron on amphibians following field applications, delays in R. aurora development could reduce annual survivorship, should their tadpole habitat dry up before the completion of metamorphosis. Furthermore, delays in larval development may put R. aurora out of synchronization with available food sources (Schuytema and Nebeker 1998). Studies Conducted in the Baker River Watershed: • The National Park Service’s, Natural Resource Preservation Program conducted an amphibian inventory of the North Cascades National Park Service Complex from 1989-2002. All surveys were conducted outside of the Baker River Project area (Holmes and Glesne 1999). o During the 1993-1994 survey seasons, pitfall traps, installed in Park Slough near Newhalem, captured red-legged frogs. o In 1996 red-legged frogs were observed during lake/pond surveys of the Big Beaver Watershed. o In 1998 a total of 19 streams and 72 lakes and ponds were sampled in the Thunder and Bridge Creek watersheds. The closest survey site (identified as LS-17) to the PSE project area was located approximately 1 km (0.6 mi) from Baker Lake on the north side of Bacon Peak, in the Noisy creek watershed. Sampling of lake/pond habitats for amphibians was done using two methods: shoreline search (visual encounter), and funnel trapping with collapsible nylon Unpublished Works © 2003, Puget Sound Energy, Inc. 5 Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 • • • • mesh minnow traps. Streams were sampled in a one meter wide belt transect; ten belt transects one meter wide were sampled in each 100 m (328 ft) stream reach. Each one meter wide belt transect was visually inspected. A kick net was then was placed in the stream and all substrate upstream within one meter of the net was picked up and examined. A pond (BD-02-01) near State Route 20 was the only site that Red-legged frogs were found in 1998 (Holmes and Glesne 1999). The Washington Department of Fish and Wildlife, Priority Habitat and Species database contains 4 records of red-legged frogs in the Baker River drainage from 1900 to 1992. The date, observer, and State Plan XY location of each observation is available. The database also includes the life-history stage of each observed R. aurora (i.e., adult, juvenile, or egg mass). Survey methods are not included. This data is available from WDFW GIS programmer Lori Guggenmos www.wa.gov/wdfw/hab/phspage.htm. Hamer Environmental conducted amphibian surveys in 2001-2002 in the reservoir fluctuation zones of the Baker River Project area. Sample areas were located using orthoquads and habitat cover maps. Visual encounter surveys, dip-netting, stream surveys, and funnel trapping were all used to locate amphibians in their various stages of development. A total of 28 red-legged frogs (8 adult/juveniles, 3 tadpoles, and 17 egg masses) were encountered during the three survey seasons (summer/fall 2001, spring 2002). The unpublished report contains more detailed information on the survey methods used, total numbers of red-legged frogs captured during each survey season, and a habitat description of each observed individual (Martin and Kruger 2002). Hamer Environmental conducted Oregon spotted frog surveys in the summer of 2001. Don Gay, a wildlife biologist at Mt. Baker Snoqualmie National Forest, and field biologists from Hamer Environmental identified all lakes and ponds within the Baker River watershed. Survey sites were then selected from the recently compiled list of lakes and ponds, based on their potential as optimal habitat for the Oregon spotted frog. All the sites surveyed were less than 2,000 ft (610 m) in elevation. A total of 22 sites were sampled within the Baker River watershed. Surveys were conducted on warm sunny days, between 15 June and 15 September 2001. Two visits were conducted with 21 days between visits. Survey methods consisted of visual encounter, dip-netting and funnel trapping. Oregon Spotted frogs were not observed during either survey period, however, a total of 10 red-legged frogs (7 adult / juvenile, and 3 tadpoles) were encountered during the 2 survey visits (Kruger 2002). Mount Baker Snoqualmie National Forest has GIS covers available for the red-legged frog. This data is available from Puget Sound Energy, Tony Fuchs, [email protected]. Unpublished Works © 2003, Puget Sound Energy, Inc. 6 Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 Literature Cited: Adams, M. J. 1999. Correlated Factors in Amphibian Decline: Exotic Species and Habitat Change in Western Washington. Journal of Wildlife Management 63(4):11621171. Adams, M.J. 2000. Pond permanence and the effects of exotic vertebrates on Anurans. Ecological Applications 10(2):559-568. Aubry, K.B., and P.A. Hall. 1991. Terrestrial amphibian communities in the southern Washington Cascade Range. Pages 327-338 in L.F. Ruggiero, K.B. Aubry, A.B. Carey, and M.H. Huff, technical coordinators. Wildlife and vegetation of unmanaged Douglasfir forests. U.S. Forest Service General Technical Report PNW-GTR-285. Belden, L.K., and A.R.Blaustein. 2002. Exposure of red-legged frog embryos to ambient UV-B radiation in the field negatively affects larval growth and development. Oecologia 130:551-554. Blaustein, A.R., J.J. Beatty, D.H. Olson, and R.M. Storm. 1995. Red-legged frog (Rana aurora). Pages 44-48 in The Biology of Amphibians and Reptiles in Old-Growth Forests in the Pacific Northwest. General Technical Report PNW-GTR-337. U.S. Forest Service, Pacific Northwest Research Station. Brown, H.A. 1975. Reproduction and development of the red-legged frog, Rana aurora in northwestern Washington. Northwest Science 49(4): 241-250. Calef, G.W. 1973. Spatial distribution and “effective” breeding population of red-legged frogs (Rana aurora) in Marion Lake, British Columbia. Canadian Field-Naturalist 87:279-284. Cook, D., and M.R. Jennings. 2001. Rana aurora draytonii; Predation. Herpetological Review 32(2):182-183. Corkran, C.C., and C. Thomas. 1996. Amphibians of Oregon, Washington and British Columbia. Lone Pine Publishing. Redmond, Washington. Gomez, D.M., and R.G. Anthony. 1996. Amphibian and reptile abundance in riparian and upslope areas of five forest types in western Oregon. Northwest Science 70( 2):109117. Green, D.M., and R.W. Campbell. 1984. Red-legged frog. Pages 77-79 in The Amphibians of British Columbia. British Columbia Provincial Museum; Handbook No. 45. Unpublished Works © 2003, Puget Sound Energy, Inc. 7 Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 Gregory, P.T. 1979. Predator avoidance, behavior of the red-legged frog (Rana aurora). Herpetologica 35(2):175-184. Hayes, M.P., and M.M. Miyamoto. 1984. Biochemical, behavioral and body size differences between Rana aurora and R. a. draytonii. Copeia 1984(4):1018-1022. __________., C.A. Pearl, and C.J. Rombough. 2001. Rana aurora aurora; movement. Herpetological Review 32(1):35-36. Holmes, R.E., and R.S. Glesne. 1999. NOCA NRPP Amphibian inventory North Cascades National Park Service Complex. North Cascades National Park Service Complex, 2105 State Route 20, Sedro-Woolley, WA 98284-9314. 84pp. Kiesecher, J.M., and A.R. Blaustein. 1998. Effects of introduced bullfrogs and smallmouth bass on microhabitat use, growth and survival of native red-legged frogs (Rana aurora). Conservation Biology 12(4):776-787. _____________., A.R. Blaustein, and C.L. Miller. 2001. Potential mechanisms underlying the displacement of native red-legged frogs. Ecology 82(7):1964-1970. Kruger, L. 2002. Oregon spotted frog inventory of the Baker River Project. Relicense Study No. T11. Unpublished Work. Puget Sound Energy, Inc. Tony Fuchs Licht, L.E. 1969. Comparative breeding behavior of the red-legged frog (Rana aurora aurora) and the western spotted frog (Rana pretiosa pretiosa) in southwestern British Columbia. Canadian Journal of Zoology 47:1287-1299. _________. 1971. Breeding habits and embryonic thermal requirements of the frogs, Rana aurora aurora and Rana pretiosa pretiosa, in the Pacific Northwest. Ecology 52(1):116-124. _________. 1974. Survival of embryos tadpoles, and adults of the frogs, Rana aurora aurora and Rana pretiosa pretiosa sympatric in southwestern British Columbia. Canadian Journal of Zoology 52:613-627. _________. 1986. Food and feeding behavior of sympatric red-legged frogs, Rana aurora, and spotted frogs, Rana pretiosa, in southwestern British Columbia. Canadian Field-Naturalist 100:22-31. Martin, R., and Kruger, L. 2002. Amphibian surveys in the reservoir fluctuation zones of the Baker Lake Project area T17. Unpublished Work © Puget Sound Energy, Inc. Tony Fuchs. Nussbaum, R.A., E.D. Brodie, Jr., and R.M. Storm. 1983. Red-legged frog Rana aurora Baird and Girard. Pages 157-161 in Amphibians and Reptiles of the Pacific Northwest. University Press of Idaho. Unpublished Works © 2003, Puget Sound Energy, Inc. 8 Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 Rabinowe, J.H., J.T. Serra, M.P. Hayes, and T. Quinn. 2002. Rana aurora aurora (northern red-legged frog); diet. Herpetological Review 33(2):128. Schuytema, G.S., and A.V. Nebeker. 1998. Comparative toxicity of Diuron on survival and growth of Pacific treefrog, bullfrog, red-legged frog, and African clawed frog embryos and tadpoles. Archives of Environmental Contamination and Toxicology 34:370-376. Storm, R.M. 1960. Notes on the breeding biology of the red-legged frog (Rana aurora aurora). Herpetologica 16:251-258. Washington Department of Fish and Wildlife. 1997. Washington gap analysis. Washington Cooperative Fish and Wildlife Research Unit, University of Washington, Seattle, WA, USA. Available online at ftp://198.187.3.50/pub/gapdata/herps/gifs/raau.gif. January 2003. Literature Review: Aubry, K.B. 2000. Amphibians in managed, second-growth Douglas-fir forests. Journal of Wildlife Management 64(4):1041-1052. Blaustein, A.R., and R.K. O’Hara. 1986. An investigation of kin recognition in redlegged frog (Rana aurora) tadpoles. Journal of Zoology, London 209:347-353. ____________., P.D. Hoffman, J.M. Kiesecker, and J.B. Hays. 1996. DNA repair activity and resistance to solar UV-B radiation in eggs of the red-legged frog. Conservation Biology 10(5):1398-1402. Chivers, D.P., J.M. Kiesecker, E.L. Wildy, L.K. Belden, L.B. Kats, and A.R. Blaustein. 1999. Avoidance response of post-metamorphic Anurans to cues of injured conspecifics and predators. Journal of Herpetology 33(3):472-476. Davidson, C., B.H. Shaffer, and M.R. Jennings. 2001. Declines of the California redlegged frog: climate, UV-B, habitat and pesticides hypotheses. Ecological Applications 11(2):464-479. Dumas, P.C. 1966. Studies of the Rana species complex in the Pacific Northwest. Copeia 1:60-74. Fellers, G.M., A.E. Launer, G. Rathbun, S. Bobzien, J. Alvarez, D. Sterner, R.B. Seymour, and M. Westphal. 2001. Overwintering tadpoles in the California red-legged frog (Rana aurora draytonii). Herpetological Review 32(3):156-157. Unpublished Works © 2003, Puget Sound Energy, Inc. 9 Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 Kiesecker, J.M., and A.R. Blaustein. 1997. Population differences in responses of redlegged frogs (Rana aurora) to introduced bullfrogs. Ecology 78(6):1752-1760. __________., D.P. Chivers, A. Marco, C. Quilchanos, M.T. Anderson, and A.R. Blaustein. 1999. Identification of disturbance signal in larval red-legged frogs, Rana aurora. Animal Behaviour 57:1295-1300. Lawler, S. P., D. Dritz, T. Strange, and M. Holyoak. 1999. Effects of introduced mosquitofish and bullfrogs on the threatened California red-legged frog. Conservation Biology 13(3):613-622. Rathbun, G.B., N.J. Scott, Jr., and T.G. Murphey. 1997. Rana aurora draytonii (California red-legged frog); Behavior. Herpetological Review 28(2):85-86. ___________. 1998. Rana aurora draytonii; egg predation. Herpetological Review 29(3):165. ___________., and J. Schneider. 2001. Translocation of California red-legged frogs (Rana aurora draytonii). Wildlife Society Bulletin 29(4):1300-1303. Unpublished Works © 2003, Puget Sound Energy, Inc. 10 Baker River Project Terrestrial Working Group Analysis Species: Final Report 2/21/03 Figure 1. Core and peripheral habitat zones for the red-legged frog in Washington State (Washington Gap Analysis Project 1997). Unpublished Works © 2003, Puget Sound Energy, Inc. 11