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|Baum RE, Peterson CR. 2005. Occurrence, distribution, relative abundance, and habitat recommendations of amphibians and reptiles in Bighorn Canyon National Recreation Area. Pocatello, ID: Idaho State University. 133 p.
|The primary goals of this two-year study were to inventory > 90% of the herpetofaunal species known to occur in the area, and to gather additional data regarding the distribution, relative abundance, and habitat relationships of these species to assist in their management and future monitoring. Surveys of amphibians and reptiles in Bighorn Canyon National Recreation Area (BICA) were conducted during the summer of 2001 in four weeks of sampling occurring from mid-May to early August, and in 2002 in six weeks of sampling occurring from late May to mid-July. A variety of sampling techniques was employed to maximize our chances of detecting the occurrence of all species. Visual encounter surveys were the primary method used (140 searches conducted).
This method was supplemented with calling surveys, road driving, terrestrial funnel trapping, incidental observations, and contributed observations. In 2002, we used Geographic Information Systems (GIS) to design a stratified, random sampling scheme based on topography (slope and aspect) and vegetation cover. A total of 395 observations was recorded - 213 amphibians and 182 reptiles. Thirteen (13) of the 15 species known to occur in Bighorn Canyon were found to be present by our surveys. Four of the 13 species were amphibians: Woodhouse�s Toad (Bufo woodhousii), Plains Spadefoot (Spea bombifrons), Boreal Chorus Frog (Pseudacris maculata), and Northern Leopard Frog (Rana pipiens).
The 9 reptile species found were Painted Turtle (Chrysemys picta), Spiny Softshell (Apolone spinifera), Greater Short-horned Lizard (Phrynosoma hernandesi), Common Sagebrush Lizard (Sceloporus graciosus), Eastern Racer (Coluber constrictor), Gopher Snake (Pituophis catenifer), Terrestrial Garter Snake (Thamnophis elegans), Common Garter Snake (Thamnophis sirtalis), and Western Rattlesnake (Crotalus viridis). One reptile species, Snapping Turtle (Chelydra serpentina), was observed outside the park boundary. One amphibian species, the Tiger Salamander (Ambystoma tigrinum) was documented in 1982 and 1985, but was not observed during our surveys. Also, one reptile species, the Pale Milk Snake (Lampropeltis triangulum), has been documented to occur in BICA, but was not detected during our surveys.
Species detected during our surveys ranged in distribution from limited to widespread, and their relative abundance ranged from uncommon to abundant. Amphibian species that have undergone significant declines in parts of Wyoming and Montana, such as Northern Leopard Frogs, had a limited distribution in Bighorn Canyon, but were found to be common at sites where they did occur. Woodhouse�s Toads were encountered at the highest number of wetland sites and were common at those sites. Boreal Chorus Frogs and Northern Leopard Frogs were also common at wetland sites but Plains Spadefoots were uncommon. Common Sagebrush Lizards were the most frequently encountered reptile species and were widely distributed and abundant. We found Painted Turtles, Eastern Racers, and Terrestrial and Common Garter Snakes to be limited in distribution but common. Gopher Snakes and Western Rattlesnakes were widespread and found to be uncommon to common, depending on the type of habitat.
Greater Short-horned Lizards were uncommon with a spotty distribution. Observations of Snapping Turtles and Spiny Softshells were only recorded once during our surveys and these species are therefore considered limited and uncommon. The amphibian species detected were found to occur in only aquatic or wetland habitats, while the reptile species detected were found in a variety of habitat types. Of the reptile species, Common Sagebrush Lizards were most frequently found in juniper/mountain mahogany or disturbed/barren habitats, while Gopher Snakes and Terrestrial Garter Snakes were primarily found in riparian or disturbed/barren habitats, and W. Rattlesnakes were detected most often in desert shrubland or disturbed/barren habitats.
|Report pdf - 7.4MB