A status survey for spotted frogs (Rana pretiosa), wood frogs (Rana sylvatica), and boreal toads (Bufo boreas) in the mountains of southern and eastern Wyoming

Authors(s): C. S. Garber

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Publication Date: 0000-00-00

Type: partial fulfillment for USFWS Cooperative agreement No. 14-48-0006-92-919

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Abstract: Many species of amphibians have experienced either general population declines or extirpations throughout the world. Within Wyoming, indications that the spotted frog (Rana pretiosa), wood frog (Rana sylvatica) and boreal toad (Bufo boreas) were declining prompted this two year status survey for these species in the mountains of southern and eastern Wyoming. Surveys for these species were conducted in suitable habitat in areas of previously known historical records. Surveys were conducted by walking slowly thorugh suitable habitat, looking for adults, eggs or young. Information on the numbers of amphibian species encountered, survey effort, habitat use and threats were recorded on a standard form and entered into a computer database. A total 358 man hours were spent surveying 216 linear kilometers of habitat at 408 sites. Amphibians were detected at 231 (56%) sites. In addition to the target species, tiger salamanders (Ambystoma tigrinum), leopard frogs (Rana pipiens), and boreal chorus frogs (Pseudacris triseriata) were also documented. All known sites for the target species occur on lands administered by the US Forest Service. The wood frog was the most common species encountered, being found at 128 sites, followed by the boreal chorus frog which was found at 112 sites. The population status of these two species appears to be secure. Tiger salamanders and leopard frogs were each found at 16 sites, but it is unclear what their population status is due to a lack of historical population information. A disjunct population of spotted frogs in the Bighorn Mountains was surveyed and they are now known from only 4 sites in one small drainage. Although common at these sites, this population is vulnerable. It is recommended that a management plan be developed and existing sites be protected in lieu of listing this population as Federally Threatened. Boreal toads have declined drastically in the survey area; they were only found at 5 sites during this survey. None were found in the Medicine Bow Mountains where the decline seems to be the most serious. Only 6 records are known from the Medicine Bow Mountains from the past 4 years and breeding has not been documented since 1987. Based on the findings of this survey, it is recommended that the Medicine Bow/Laramie Range population of boreal toads be listed as Federally Endangered. Data gathered on identifiable threats indicate that exotic Salmonids and habitat destruction by logging pose the greatest threat to montane amphibians. Population studies and studies on the effects of logging on montane amphibians are needed.

Keywords: animal, herpetology, amphibian, population, breeding, habitat, Wyoming, frog, Anura, Ranidae, Bufonidae, Bufo, toad, salamander, Caudata, spotted frog, Rana pretiosa, wood frog, Rana sylvatica, boreal toad, Bufo boreas, tiger salamander, Ambystoma tigrinum, Ambystomatidae, leopard frog, Rana pipiens, boreal chorus frog, Pseudacris triseriata, Hylidae, Salmonidae