Pacific Treefrog - Pseudacris regilla
Adults have a dark, conspicuous eye line extending from the nostril to the shoulder. Basic coloration varies, with background color green, brown, gray, reddish, or bronze. Dark spots and stripes are often visible on the head, back, and legs. Most have a dark Y or triangular spot on the head between the eyes. Adult body length is 0.75 to 2 inches. Eggs and Tadpoles: Eggs are laid in small clusters of 10 to 70. The tadpoles are brown/bronze with eyes located on the sides of the head.
This is the only frog in Montana with a combination of obvious toe pads and an eye stripe ending at the shoulder.
Western Hemisphere Range
Observations in Montana Natural Heritage Program Database
Number of Observations:
(Click on the following maps and charts to see full sized version)
Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
Pacific Chorus Frogs are regularly found in the water only during the breeding period in spring. They announce their presence during this time by calling frequently at night and sporadically throughout the day. Following breeding, they move into adjacent uplands and are rarely seen. In western Montana they breed in temporary ponds in lower elevation forests and intermountain valleys shortly after snowmelt. Eggs hatch in 2 to 3 weeks and tadpoles take 8 to 10 weeks to metamorphose. Use shallow, quiet waters for breeding. Move along ground or in low shrubs at night. Take shelter during day in dense vegetation, under rocks/logs, in rodent burrows, etc. (Nussbaum et al. 1983).
Ecological Systems Associated with this Species
- Details on Creation and Suggested Uses and Limitations
How Associations Were Made
We associated the use and habitat quality (common or occasional) of each of the 82 ecological systems mapped in Montana for
vertebrate animal species that regularly breed, overwinter, or migrate through the state by:
- Using personal observations and reviewing literature that summarize the breeding, overwintering, or migratory habitat requirements of each species (Dobkin 1992, Hart et al. 1998, Hutto and Young 1999, Maxell 2000, Foresman 2012, Adams 2003, and Werner et al. 2004);
- Evaluating structural characteristics and distribution of each ecological system relative to the species' range and habitat requirements;
- Examining the observation records for each species in the state-wide point observation database associated with each ecological system;
- Calculating the percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system to get a measure of "observations versus availability of habitat".
Species that breed in Montana were only evaluated for breeding habitat use, species that only overwinter in Montana were only evaluated for overwintering habitat use, and species that only migrate through Montana were only evaluated for migratory habitat use.
In general, species were listed as associated with an ecological system if structural characteristics of used habitat documented in the literature were present in the ecological system or large numbers of point observations were associated with the ecological system.
However, species were not listed as associated with an ecological system if there was no support in the literature for use of structural characteristics in an ecological system, even if
point observations were associated with that system.
Common versus occasional association with an ecological system was assigned based on the degree to which the structural characteristics of an ecological system matched the preferred structural habitat characteristics for each species as represented in scientific literature.
The percentage of observations associated with each ecological system relative to the percent of Montana covered by each ecological system was also used to guide assignment of common versus occasional association.
If you have any questions or comments on species associations with ecological systems, please contact the Montana Natural Heritage Program's Senior Zoologist.
Suggested Uses and Limitations
Species associations with ecological systems should be used to generate potential lists of species that may occupy broader landscapes for the purposes of landscape-level planning.
These potential lists of species should not be used in place of documented occurrences of species (this information can be requested at: http://mtnhp.org/requests/default.asp
) or systematic surveys for species and evaluations of habitat at a local site level by trained biologists.
Users of this information should be aware that the land cover data used to generate species associations is based on imagery from the late 1990s and early 2000s and was only intended to be used at broader landscape scales.
Land cover mapping accuracy is particularly problematic when the systems occur as small patches or where the land cover types have been altered over the past decade.
Thus, particular caution should be used when using the associations in assessments of smaller areas (e.g., evaluations of public land survey sections).
Finally, although a species may be associated with a particular ecological system within its known geographic range, portions of that ecological system may occur outside of the species' known geographic range.
- Adams, R.A. 2003. Bats of the Rocky Mountain West; natural history, ecology, and conservation. Boulder, CO: University Press of Colorado. 289 p.
- Dobkin, D. S. 1992. Neotropical migrant land birds in the Northern Rockies and Great Plains. USDA Forest Service, Northern Region. Publication No. R1-93-34. Missoula, MT.
- Foresman, K.R. 2012. Mammals of Montana. Second edition. Mountain Press Publishing, Missoula, Montana. 429 pp.
- Hart, M.M., W.A. Williams, P.C. Thornton, K.P. McLaughlin, C.M. Tobalske, B.A. Maxell, D.P. Hendricks, C.R. Peterson, and R.L. Redmond. 1998. Montana atlas of terrestrial vertebrates. Montana Cooperative Wildlife Research Unit, University of Montana, Missoula, MT. 1302 p.
- Hutto, R.L. and J.S. Young. 1999. Habitat relationships of landbirds in the Northern Region, USDA Forest Service, Rocky Mountain Research Station RMRS-GTR-32. 72 p.
- Maxell, B.A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to U.S. Forest Service Region 1. Missoula, MT: Wildlife Biology Program, University of Montana. 161 p.
- Werner, J.K., B.A. Maxell, P. Hendricks, and D. Flath. 2004. Amphibians and reptiles of Montana. Missoula, MT: Mountain Press Publishing Company. 262 p.
- Commonly Associated with these Ecological Systems
Forest and Woodland Systems
Human Land Use
Recently Disturbed or Modified
Wetland and Riparian Systems
- Occasionally Associated with these Ecological Systems
Forest and Woodland Systems
Human Land Use
Recently Disturbed or Modified
Shrubland, Steppe and Savanna Systems
Wetland and Riparian Systems
Severe droughts can affect populations (Schaub and Larsen 1978). Primarily nocturnal (Black 1970).
Northern ID: males arrive in breeding ponds early to mid-April; females mid- to late April. Eggs layed April to mid-May; hatch early to mid-May. Metamorphose mid-Jul to mid-September. Prefer warmer, more open ponds, but observed calling in water 2 C, air 0.5 C (Schaub and Larsen 1978).
- Literature Cited AboveLegend: View Online Publication
- Black, J.H. 1970a. Amphibians of Montana. Montana Wildlife, Montana Fish and Game Commission. Animals of Montana Series 1970(1): 1-32.
- Nussbaum, R.A., E.D. Brodie, Jr. and R.M. Storm. 1983. Amphibians and reptiles of the Pacific Northwest. University of Idaho Press. Moscow, ID. 332 pp.
- Schaub, D. L. and J. H. Carson, Jr. 1978. The reproductive ecology of the Pacific treefrog Hyla regilla. Herpetologica 34(4): 409-416.
- Additional ReferencesLegend: View Online Publication
Do you know of a citation we're missing?
- [WWPC] Washington Water Power Company. 1995. 1994 wildlife report Noxon Rapids and Cabinet Gorge Reservoirs. Washington Water Power Company. Spokane, WA.
- Allan, D.M. 1973. Some relationships of vocalization to behavior in the Pacific treefrog (Hyla regilla). Herpetologica 29(4): 366-371.
- Anderson, M.E. 1977. Aspects of the ecology of two sympatric species of Thamnophis and heavy metal accumulation with the species. M.S. thesis, University of Montana, Missoula. 147 pp.
- Anzalone, C.R., L.B. Kats and M.S. Gordon. 1998. Effects of solar UV-B radiation on embryonic development in Hyla cadaverina, Hyla regilla, and Taricha torosa. Conservation Biology 12: 646-653.
- Arnold, S.J. 1986. Life history notes. Hyla regilla (Pacific treefrog). Herpetological Review 17(2): 44.
- Awbrey, F.T. 1978. Social interaction among chorusing Pacific tree frogs (Hyla regilla). Copeia 1978(2): 208-214.
- Ball, R.W. and D.L. Jameson. 1966. Premating isolating mechanisms in sympatric and allopatric Hyla regilla and Hyla californiae. Evolution 20: 533-551.
- Banta, B.H. 1961. On the concurrence of Hyla regilla in the Lower Colorado River, Clark County, Nevada. Herpetologica 17: 106-108.
- Baumann, M. 1993. The Pacific treefrog (Hyla regilla). Vivarium 4(4): 32-33.
- Blair, W.F. 1958a. Call structure and species groups in U.S. treefrogs (Hyla). Southwestern Naturalist 5: 129-135.
- Blaustein, A.R., J.J. Beatty, H. Deanna, and R.M. Storm. 1995. The biology of amphibians and reptiles in old-growth forests in the Pacific Northwest. General Technical Report PNW-GTR-337. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 98 p.
- Boundy, J. 2001. Herpetofaunal surveys in the Clark Fork Valley region, Montana. Herpetological Natural History 8: 15-26.
- Bowerman, J. and P.T.J. Johnson. 2003. Timing of trematode-related malformations in Oregon spotted frog and Pacific treefrogs. Northwestern Naturalist 84:142-145.
- Bradford, D.F. 1989. Allotopic distribution of native frogs and introduced fishes in high Sierra Nevada lakes of California: Implication of the negative effect of fish introductions. Copeia 1989(3): 775-778.
- Bradford, D.F., C. Swanson, and M.S. Gordon. 1994. Effects of low pH and aluminum on amphibians at high elevation in Sierra Nevada, California. Canadian Journal of Zoology 72: 1272-1279.
- Bradford, D.F., D.M. Graber, and F. Tabatabai. 1994. Population declines of the native frog, Rana muscosa, in Sequoia and Kings Canyon National Parks, California. Southwestern Naturalist 39(4): 323-327.
- Brattstrom, B.H. and J.W. Warren. 1955. Observations on the ecology and behavior of the Pacific treefrog (Hyla regilla). Copeia 1955(3): 181-191.
- Brenowitz, E.A. 1989. Neighbor call amplitude influences aggressive behavior and intermale spacing in choruses of the Pacific treefrog (Hyla regilla). Ethology 83(1): 69-79.
- Brenowitz, E.A. and G.J. Rose. 1994. Behavioural plasticity mediates aggression in choruses of the Pacific treefrog. Animal Behaviour 47: 633-641.
- Brown, H.A. 1975a. Embryonic temperature adaptations of the Pacific treefrog (Hyla regilla). Comparative Biochemistry and Physiology 51A: 863-873
- Brunson, R.B. 1955. Check list of the amphibians and reptiles of Montana. Proceedings of the Montana Academy of Sciences 15: 27-29.
- Brunson, R.B. and H.A. Demaree, Jr. 1951. The herpetology of the Mission Mountains, Montana. Copeia (4):306-308.
- Buchan, A., J. Charbonneau, K. Johnson, T. Englund, L. Sun, and S. Wagner. 2005. Project croak!: Balancing selection for color change in Pseudacris regilla--"It ain't easy bein' green". Abstract. Northwestern Naturalist 86:86.
- Buchan, A., L. Sun, and R.S. Wagner. 2004. Seasonal demography as a consequence of metabolism, behavior, and color morphology in Pseudacris regilla. Abstract. Northwestern Naturalist 85:69.
- Bull, E.L., J.W. Deal, and J.E. Hohmann. 2001. Avian and amphibian use of fenced and unfenced stock ponds in northeastern Oregon forests. US Forest Service Research Paper PNW 539: 1-9.
- Calhoun, R.E. and D.L. Jameson. 1970. Canonical correlation between variation in weather and variation in size in the Pacific tree frog, Hyla regilla, in southern California. Copeia 1970: 124-134.
- Call, D.R., and J.G. Hallett. 1998. PCR primers for microsatellite loci in the anurans Rana luteiventris and Hyla regilla. Molecular Ecology 7: 1083-1090.
- Claussen, D.L. 1971. A comparative study of the thermal and water relations of the tailed frog, Ascaphus truei and the Pacific treefrog, Hyla regilla. Ph.D. Dissertation. University of Montana, Missoula, MT. 103 p.
- Claussen, D.L. 1973a. The thermal relations of the tailed frog (Ascaphus truei) and the Pacific treefrog (Hyla regilla). Comparative Biochemistry and Physiology 44a: 137-153.
- Claussen, D.L. 1973b. The water relations of the tailed frog (Ascaphus truei) and the Pacific treefrog (Hyla regilla). Comparative Biochemistry and Physiology 44a: 155-171.
- Confluence Consulting Inc. 2010. Montana Department of Transportation Wetland Mitigation Monitoring Reports (various sites). MDT Helena, MT.
- Cope, E.D. 1875. Check-list of North American Batrachia and Reptilia; with a systematic list of the higher groups, and an essay on geographical distribution. Based on the specimens contained in the U.S. National Museum. U.S. Natioanl Museum Bulletin 1: 1-104.
- Croes, S.A. and R.E. Thomas. 2000. Freeze tolerance and cryoprotectant synthesis of the Pacific tree frog (Hyla regilla). Copeia 2000(3): 863-868.
- Crother, B.I. (ed.) 2008. Scientific and standard English names of amphibians and reptiles of North America north of Mexico. SSAR Herpetological Circular No. 37:1-84.
- Cunningham, J.D. and D.P. Mullally. 1956. Thermal factors in the ecology of the Pacific treefrog. Herpetologica 12: 68-79.
- Curtis, S. 1994. The big sleep. Montana Outdoors 25(6): 2-7.
- Davis, T.M., I.N. Flamarique, and K. Ovaska. 2000. Effects of UV-B on amphibian development: embryonic and larval survival of Hyla regilla and Rana pretiosa. Froglog 16: 3.
- De Vito, J., D.P. Chivers, J.M. Kiesecker, L.K. Belden, and A.R. Blaustein. 1999. Effects of snake predation on aggregation and metamorphosis of Pacific treefrog (Hyla regilla) larvae. Journal of Herpetology 33(3): 504-507.
- Duellman, W. 1970. The hylid frogs of Middle America Volume 2. Monograph of the Museum of Natural History, University of Kansas 1: 484-493.
- Eakin, R.M. 1947. Stages in the normal development of Hyla regilla. University of California Publications in Zoology 51: 245-257.
- Farrell, M.P. and J.A. MacMahon. 1969. An eco-physiological study of water economy in eight species of tree frogs (Hylidae). Herpetologica 25: 279-294.
- Feaver, E.P. 1971. Breeding pool selection and larval mortality of three California amphibians: Ambystoma tigrinum californiense Gray, Hyla regilla Baird and Girard, and Scaphiopus hammondii hammondii Girard. M.S. Thesis, California State University at
- Foster, W.A. 1967. Chorus structure and vocal response in the Pacific treefrog (Hyla regilla). Herpetologica 23(2): 100-104.
- Franz, R. 1971. Notes on the distribution and ecology of the herpetofauna of northwestern Montana. Bulletin of the Maryland Herpetological Society 7: 1-10.
- Gardner, J.D. 1995. Anura: Pseudacris regilla (Pacific Chorus Frog). Reproduction. Herpetological Review 26(1): 32.
- Gaudin, A.J. 1965. Larval development of the tree frogs (Hyla regilla) and (Hyla californiae). Herpetologica 21(2): 117-130.
- Gerlanc, N.M. and G.A. Kaufman. 2005. Habitat of origin and changes in water chemistry influence development of western chorus frogs. Journal of Herpetology 39(2):254-265.
- Gildart, R.C. and J. Wassink. 1982. Montana wildlife. Montana Geographic Series. Number three. Montana Magazine, Inc. Helena, MT. 128 p.
- Goldberg, S.R. and C.R. Bursey. 2001. Persistence of the nematode, Oswaldocruzia pipiens (Molineidae) in the Pacific treefrog (Hyla regilla) (Hylidae) from California. Bulletin of the Southern California Academy of Sciences 100(1): 44-50.
- Goldberg, S.R., C.R. Bursey, and E.W.A. Gergus. 2001. Helminth communities of subpopulations of the pacific treefrog (Hyla regilla) (Hylidae), from Baja California, Mexico. Southwestern Naturalist 46(2): 223-229.
- Goodsell, J.A., and L.B. Kats. 1999. Effect of introduced mosquitofish on Pacific treefrogs and the role of alternative prey. Conservation Biology 13(4): 921-924.
- Govindarajulu, P. 2000. Estimation of daily survival rates of Hyla regilla tadpoles in the wild. Northwestern Naturalist 81(2):74.
- Hanauska-Brown, L., B.A. Maxell, A. Petersen, and S. Story. 2014. Diversity Monitoring in Montana 2008 – 2010 Final Report. Montana Fish, Wildlife & Parks. Helena, MT. 78 pp.
- Hansen, L.J., D.L. Fabacher, R. Calfee. 2002. The role of the egg jelly coat in protecting Hyla regilla and Bufo canorus embryos form ultraviolet B radiation during development. Environmental Science and Pollution Research 9(6): 412-416.
- Hebard, W.B. and R.B. Brunson. 1963. Hind limb anomalies of a western Montana population of the pacific tree frog, Hyla regilla. Copeia 1963: 570-572.
- Hendricks, P. 2000. Amphibian and reptile survey of the Thompson Chain of Lakes. A report to the Montana Department of Fish, Wildlife, and Parks. Montana Natural Heritage Program, Helena, MT. 15 p.
- Hendricks, P. and J.D. Reichel. 1996. Amphibian and reptile survey of the Bitterroot National Forest: 1995. Montana Natural Heritage Program. Helena, MT. 95 p.
- Hossack, B., D. Pilliod, and P.S. Corn. 2001b. Preliminary amphibian surveys of the National Bison Range, Lost Trail National Wildife Refuge, and Swan River National Wildlife Refuge: 2001. USGS Northern Rocky Mountain Science Center, Aldo Leopold Wilderness Research Institute, Missoula, MT. 15 p.
- Jameson, D.L. 1956. Growth, dispersal and survival of the Pacific tree frog. Copeia 1956: 25-29.
- Jameson, D.L. 1957. Population structure and homing responses in the Pacific treefrog. Copeia 1957(3): 221-228.
- Jameson, D.L. 1966. Rate of weight loss of treefrogs at various temperatures and humidities. Ecology 47: 605-613.
- Jameson, D.L. and S. Peguegnat. 1971. Estimation of relative viability and fecundity of color polymorphism in anurans. Evolution 25: 180-194.
- Jameson, D.L., J.P. Mackey and R.C. Richmond. 1966. The systematics of the Pacific tree frog, Hyla regilla. Proceedings of the California Academy of Sciences 33(19): 551-620.
- Jameson, D.L., J.P. Mackey, and M. Anderson. 1973. Weather, climate, and the external morphology of Pacific tree toads. Evolution 27: 285-302.
- Jameson, D.L., W. Taylor and J. Mountjoy. 1970. Metabolic and morphological adaptation to heterogenous evironments by the Pacific tree toad, Hyla regilla. Evolution 24:75-89.
- Johnson, C.R. 1980. The effects of five organophosphorus insecticides on thermal stress in tadpoles of the Pacific tree frog (Hyla regilla). Zoological Journal of the Linnean Society 69: 143-147.
- Johnson, C.R. and R.B. Bury. 1965. Food of the Pacific treefrog (Hyla regilla) Baird and Girard, in northern California. Herpetologica 21: 56-58.
- Johnson, P.T.J., K.B. Lunde, E.M. Thurman, E.G. Ritchie, S.N. Wray, D.R. Sutherland, J.M. Kapfer, T.J. Frest, J. Bowerman, and A.R. Blaustein. 2002. Parasite (Ribeiroia ondatrae) infection linked to amphibian malformations in the western United States. Ecological Monographs 72(2):151-168.
- King, J. and S. Wagner. 2005. Pacific Northwest amphibian management and application of glyphosate-based herbicides. Abstract. Northwestern Naturalist 86:102.
- Koller, R.L., and A.J. Gaudin. An analysis of helminth infections in Bufo boreas (Amphibia: Bufonidae) and Hyla regilla (Amphibia: Hylidae) in southern California. Southwestern Naturalist 21(4): 503-509.
- Kupferberg, S.J. 1993. Bullfrogs (Rana catesbeiana) invade a northern California river: a plague or species coexistence? Bulletin of the Ecological Society of America 74: 319-320.
- Kupferberg, S.J. 1996. The ecology of native tadpoles (Rana boylii and Hyla regilla) and the impact of invading bullfrogs (Rana catesbeiana) in a northern California river. Ph.D. dissertation, University of California at Berkeley. Berkeley, CA. 289 p.
- Kupferberg, S.J. 1997. Facilitation of periphyton production by tadpole grazing: functional differences between species. Freshwater Biology 37(2): 427-439.
- Kupferberg, S.J. 1997a. Bullfrog (Rana catesbeiana) invasion of a California river: the role of larval competition. Ecology 78(6): 1736-1751.
- Kupferberg, S.J. 1998. Predator mediated patch use by tadpoles (Hyla regilla): risk balancing or consequence of motionlessness? Journal of Herpetology 32(1): 84-92.
- Kupferberg, S.J., J.C. Marks, and M.E. Power. 1994. Effects of variation in natural algal and detrital diets on larval anuran (Hyla regilla) life-history traits. Copeia 1994(2): 446-457.
- L. L. C. Jones, W. P. Leonard and D. H. Olson, eds. 2005. Amphibians of the Pacific Northwest. Seattle Audubon Society: Seattle, WA, 227 pp.
- Leonard, W.P. and N.P. Leonard. 1996. Thamnophis sirtalis pickeringii (Puget Sound garter snake). Foraging and arboreality. Herpetological Review 27(2): 84.
- Licht, L.E. 1969b. Palatability of Rana and Hyla eggs. American Midland Naturalist 82: 296-298.
- Littlejohn, M. J. 1971. A reappraisal of mating call differentiation in Hyla cadaverina (Hyla californiae) and Hyla regilla. Evolution 25(1): 98-102.
- Livezey, R.L. 1953. Late breeding of Hyla regilla Baird and Girard. Herpetologica 9: 73.
- Loftus-Hills, J.J. and M.J. Littlejohn. 1971. Pulse repetition rate as the basis for mating call discrimination by two sympatric species of Hyla. Copeia 1971: 154-156.
- Mackey, 1958. Morphological variation among populations of the Pacific tree frog (Hyla regilla) at several elevations in western Oregon. Ph.D. thesis, University of Oregon, Eugene, Ore.
- Manville, R.H. 1957. Amphibians and reptiles of Glacier National Park, Montana. Copeia 1957: 308-309.
- Marnell, L. E. 1997. Herpetofauna of Glacier National Park. Northwestern Naturalist 78:17-33.
- Marnell, L.F. 1996. Amphibian survey of Glacier National Park, Montana. Abstract. Intermountain Journal of Sciences 2(2): 52.
- Matthews, K.R., K.L. Pope, H.K. Preisler, and R.A. Knapp. 2001. Effects of nonnative trout on pacific treefrogs (Hyla regilla) in the Sierra Nevada. Copeia 2001(4): 1130-1137.
- Matthews, K.R., R.A. Knapp, and K.L. Pope. 2002. Garter snake distributions in high-elevation aquatic ecosystems: is there a link with declining amphibian populations and nonnative trout introductions? Journal of Herpetology 36: 16-22.
- Maxell, B. A. 2000. Management of Montana's amphibians: a review of factors that may present a risk to population viability and accounts on the identification, distribution, taxonomy, habitat use, natural history, and the status and conservation of individual species. Report to USFS Region 1, Order Number 43-0343-0-0224. University of Montana, Wildlife Biology Program. Missoula, MT. 161 p.
- Maxell, B.A. 2002a. Amphibian and aquatic reptile inventories in watersheds in the South and Middle Forks of the Flathead River drainage that contain lakes being considered for application of piscicides and subsequent stocking of west slope cutthroat trout. Report to the Region 1 Office of the U.S. Forest Service and the Montana Department of Fish, Wildlife, and Parks. Montana Cooperative Wildlife Research Unit and Wildlife Biology Program, University of Montana, Missoula, MT. 62 pp.
- Maxell, B.A., J.K. Werner, P. Hendricks, and D.L. Flath. 2003. Herpetology in Montana: a history, status summary, checklists, dichotomous keys, accounts for native, potentially native, and exotic species, and indexed bibliography. Society for Northwestern Vertebrate Biology, Northwest Fauna Number 5. Olympia, WA. 135 p.
- Maxson, L.R. 1978. Immunological evidence pertaining to relationships between Old World Hyla arborea (Amphibia, Anura, Hylidae) and North American Hyla. Journal of Herpetology 12: 98-100.
- Maxson, L.R. and A.C. Wilson. 1974. Convergent morphological evolution detected by studying proteins of tree frogs in the Hyla eximia species group. Science 185: 66-68.
- Mecham, J.S. 1965. Genetic relationships and reproductive isolation in southeastern frogs of the genera Pseudacris and Hyla. American Midland Naturalist 74: 269-308.
- Miller, J. D. 1975. Interspecific food relationships of anurans in northwestern Montana and fluoride accumulation in amphibians and reptiles in northwestern Montana. M.S. thesis. University of Montana, Missoula, MT. 105 p.
- Millzner, R. 1924. A larval acanthicephalid (Centrorhynchus californicus) sp. Nov., from the mesentery of Hyla regilla. University of California, Publications in Zoology 26: 225-227.
- Moorf, S.E. 1979. Lek organization and mating strategies in the Pacific treefrog (Hyla regilla). Unpublished MS Thesis. San Diego State University.
- Morey, S.R. 1990. Microhabitat selection and predation in the Pacific Treefrog, Pseudacris regilla. Journal of Herpetology 24(3): 292-296.
- Munger, J.C., M. Gerber, K. Madrid, M.A. Carroll, W. Petersen and L. Heberger. 1998. US National Wetland inventory classifications as predictors of the occurrence of Columbia spotted frogs (Rana luteiventris) and Pacific treefrogs (Hyla regilla). Conser
- Nebeker, A.V. and G.S. Schuytema. 2000. Effects of ammonium sulfate on growth of larval northwestern salamanders, red-legged and Pacific treefrog tadpoles, and juvenile fathead minnows. Bulletin of Environmental Contamination and Toxicology 64(2):271-278.
- Nebeker, A.V., G.S. Schuytema, W.L. Griffis, and A. Cataldo. 1998. Impact of guthion on survival and growth of the frog Psuedacris regilla and the salamanders Ambystoma gracile and Ambystoma maculatum. Archives of Environmental Contamination and Toxicology 35(1):48-51.
- Needham, J.G. 1924. Observations on the life of the ponds at the head of Laguna canyon. Journal of Entomology and Zoology 16(1): 1-12.
- Northrop, Devine & Tarbell, Inc. 1994. Cabinet Gorge and Noxon Rapids hydroelectric developments: 1993 wildlife study. Unpublished report to the Washington Water Power Company, Spokane. Vancouver, Washington and Portland, Maine. 144 pp. plus appendices.
- O’Hara, R.K. and A.R. Blaustein. 1988. Hyla regilla and Rana pretiosa tadpoles fail to display kin recognition behaviour. Animal Behaviour 36(3): 946-948.
- Ovaska, K., T.M. Davis, I.N. Flamarique. 1997. Hatching success and larval survival of the frogs Hyla regilla and Rana aurora under ambient and artificially enhanced solar ultraviolet radiation. Canadian Journal Zoology 75: 1081-1088.
- Perrill, S.A. 1984. Male mating behavior in Hyla regilla. Copeia 1984(3): 727-732.
- Perrill, S.A. and R.E. Daniel. 1983. Multiple egg clutches in Hyla regilla, H. cinerea, and H. gratiosa. Copeia 1983: 513-516.
- Peterson, C.R. and J.P. Shive. 2002. Herpetological survey of southcentral Idaho. Idaho Bureau of Land Management Technical Bulletin 02-3:1-97.
- Poinar, G.O., Jr. and G.M. Thomas. 1988. Infection of frog tadpoles (Amphibia) by insect parasitic nematodes (Rhabditida). Experientia 44(6): 528-531.
- Pope, K.L. and K.R. Matthews. 2001. Movement ecology and seasonal distribution of mountain yellow-legged frog (Rana muscosa) in a high-elevation Sierra Nevada basin. Copeia 2001(3): 787-793
- Reichel, J. and D. Flath. 1995. Identification of Montana's amphibians and reptiles. Montana Outdoors 26(3):15-34.
- Reid, I.S. 2005. Amphibian, fish stocking and habitat relationships in Siskiyou Mountain Wilderness lakes, California and Oregon. Northwestern Naturalist 86:25-33.
- Reimchen, T.E. 1990. Introduction and dispersal of the Pacific Treefrog (Hyla regilla) on Queen Charlotte Islands, British Columbia. Canadian Field Naturalist 105: 288-290.
- Resnick, L.E. and D.L. Jameson. 1963. Color polymorphism in Pacific tree frogs. Science 142: 1081-1083.
- Reynolds, T.D. andT.D. Stephens. 1984. Multiple ectopic limbs in a wild population of Hyla regilla. Great Basin Naturalist 44: 166-169.
- Riley, D.R. 1981. The monophasic call of Hyla regilla (Anura: Hylidae). Copeia 1981: 230-233.
- Ripplinger, J. and R.S. Wagner. 2004. Phylogeography of northern populations of the Pacific treefrog, Pseudacris regilla. Abstract. Northwestern Naturalist 85:118-125.
- Rodgers, T. L. and W. L. Jellison. 1942. A collection of amphibians and reptiles from western Montana. Copeia (1):10-13.
- Rose, G.J. and E.A. Brenowitz. 1991. Aggressive thresholds of male pacific treefrogs for advertisement calls vary with amplitude of neighbors' calls. Ethology 89(3): 244-252.
- Rose, G.J. and E.A. Brenowitz. 1997. Plasticity of aggressive thresholds in Hyla regilla: discrete accommodation to encounter calls. Animal Behaviour 53(2): 353-361.
- Rose, G.J. and E.A. Brenowitz. 2002. Pacific treefrogs use temporal integration to differentiate advertisement from encounter calls. Animal Behaviour 63(6): 1183-1190.
- Schechtman, A.M. and J.B. Olson. 1941. Unusual temperature tolerance of an amhibian egg (Hyla regilla). Ecology 22(4): 409-410.
- Schuytema, G.S. and A.V. Nebeker. 1999. Comparative toxicity of ammonium and nitrate compounds to Pacific treefrog and African clawed frog tadpoles. Enviromental Toxicology & Chemistry 18(10): 2251-2257.
- Schuytema, G.S., A.V. Nebeker, and W.L. Griffs. 1995. Comparative toxicity of Guthion and Guthion 2S to Xenopus laevis amd Pseudacris regilla tadpoles. Bulletin of Environment, Contamination, and Toxicology 54:382-388.
- Smith, R.E. 1940. Mating and oviposition in the Pacific Coast tree toad. Science 92: 379-380.
- Snyder, W.F. and D.L. Jameson. 1965. Multivariate geographic variation of mating call in populations of the Pacific tree frog (Hyla regilla). Copeia 1965(2): 129-142.
- Soiseth, C.R. 1992. The pH and acid neutralizing capacity of ponds containing Pseudacris regilla larvae in an alpine basin of the Sierra Nevada. California Fish and Game 78(1): 11-19.
- Sparling, D.W., G.M. Fellers, and L.L. McConnell. 2001. Pesticides and amphibian population declines in California, USA. Environmental Toxicology and Chemistry 20(7): 1591-1595.
- Stearns-Roger Inc., 1975, Environmental baseline information of the Mount Vernon Region, Montana. January 31, 1975.
- Stebbins, R. C. 2003. A field guide to western reptiles and amphibians. 3rd Edition. Houghton Mifflin Company, Boston and New York. 533 p.
- Stiebler, I.B. and P.M. Narins. 1990. Temperature-dependence of auditory nerve response properties in the frog. Hearing Research 46(1-2): 63-82.
- Straughan, I.R. 1975. An analysis of the mechanisms of mating call discrimination in the frogs Hyla regilla and H. cadaverina. Copeia 1975: 415-424.
- Test, F.C. 1898. A contribution to the knowledge of the variations of the tree frog (Hyla regilla). Proceedings of the United States National Museum 21: 477-492.
- Thompson, M.D. and A.P. Russell. 2000. Phylogeography of Ambystoma macrodactylum: post glacial range expansion and resultant genetic diversity. Field Summary Report No. 1. University of Calgary. Calgary, Canada. 39 p.
- Timken, R. No Date. Amphibians and reptiles of the Beaverhead National Forest. Western Montana College, Dillon, MT. 16 p.
- Vogt, T. and D.L. Jameson. 1970. Chronological correlation between change in weather and change in morphology of the Pacific tree frog in southern California. Copeia 1970(1): 135-144.
- Wagner, W.E., Jr. 1986. Tadpoles and pollen: observations on the feeding behavior of Hyla regilla larvae. Copeia 1986(3): 802-804.
- Wassersug, R.J. 1976b. Internal oral features in Hyla regilla (Anura: Hylidae) larvae: an ontogenetic study. Occasional Papaers Museum of Natural History, University of Kansas 49: 1-24.
- Waters, D.L. 1992. Pseudacris regilla (Pacific chorus frog). Herpetological Review 23(1): 24-25.
- Watkins, T.B. 1996. Predator-mediated selection on burst swimming performance in tadpoles of the Pacific tree frog, Pseudacris regilla. Physiological Zoology 69(1): 154-167.
- Weitzel, N.H. and H.R. Panik. 1993. Long-term fluctuations of an isolated population of the Pacific chorus frog (Pseudacris regilla) in northwestern Nevada. Great Basin Naturalist 53(4): 379-384.
- Wente, W.H. 2001. Microhabitat choice in the Pacific treefrog (Hyla regilla): characteristics of a complex color polymorphism and implications for the development o fassortative mate choice within an interbreeding population. Ph.D. diss. Indiana Univer
- Wente, W.H. and J. B. Phillips. 2003. Fixed green and brown color morphs and a novel color-changing morph of the Pacific tree frog (Hyla regilla). American Naturalist 162(4): 461-473
- Wente, W.H. and J.B. Phillips. 2005. Seasonal color change in a population of Pacific treefrogs (Pseudacris regilla). Journal of Herpetology 39(1):161-165.
- Werner, J.K. and J.D. Reichel. 1996. Amphibian and reptile monitoring/survey of the Kootenai National Forest: 1995. Montana Natural Heritage Program. Helena, MT. 115 pp.
- Werner, J.K. and J.D. Reichel. 1994. Amphibian and reptile survey of the Kootenai National Forest: 1994. Montana Natural Heritage Program. Helena, MT. 104 p.
- Werner, J.K. and T. Plummer. 1995. Amphibian and reptile survey of the Flathead Indian Reservation 1993-1994. Salish Kootenai College, Pablo, MT. 55 pp.
- Werner, J.K. and T. Plummer. 1995. Amphibian monitoring program on the Flathead Indian Reservation 1995. Salish Kootenai College, Pablo, MT. 46 p.
- Werner, J.K., B.A. Maxell, P. Hendricks and D.L. Flath. 2004. Amphibians and Reptiles of Montana. Mountain Press Publishing Company: Missoula, MT. 262 pp.
- Werner, J.K., T. Plummer, and J. Weaselhead. 1998b. The status of amphibians on the Flathead Reservation, Montana. Intermountain Journal of Sciences 4(3-4): 88.
- Werner, J.K., T. Plummer, and J. Weaslehead. 1998. Amphibians and reptiles of the Flathead Indian Reservation. Intermountain Journal of Sciences 4(1-2): 33-49.
- Western EcoTech, Helena, MT., 1999, Wetland delineation report for the Haskins Landing Proposed Wetland Mitigation Area. MWFE? June 2, 1999.
- White, M. and J.A. Kolb. 1974. A preliminary study of Thamnophis near Sagehen Creek, California. Copeia 1974(1): 126-136.
- Whitney, C.L. 1973. The role of vocalizations in spacing out and mate selection in Pacific tree frogs. M.S. Thesis, The University of British Columbia, Vancouver, British Columbia.
- Whitney, C.L. 1980. The role of the 'ecounter' call in spacing of Pacific treefrogs (Hyla regilla). Canadian Journal of Zoology 58: 75-78.
- Whitney, C.L. 1981. The monophasic call of Hyla regilla (Anura: Hylidae). Copeia 1981: 230-233.
- Whitney, C.L. and J.R. Krebs. 1975a. Mate selection in Pacific tree frogs. Nature 255: 325-327.
- Whitney, C.L. and J.R. Krebs. 1975b. Spacing and calling in Pacific tree frogs (Hyla regilla). Canadian Journal of Zoology 53: 1519-1527.
- Wirsing, A.J., J.D. Roth, and D.L. Murray. 2005. Can prey use dietary cues to distinguish predators? A test involving three terrestrial amphibians. Herpetologica 61(2):104-110.
- Yoon, D. 1977. The effect of introduced fish on the amphibian life in Westfall Meadow. Yosemite Nature Notes 46: 69-70.
- Additional Sources of Information Related to "Amphibians"