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Evaluating Amphibian Declines with Site Revisits and Occupancy Models: Status of Montane Anurans in the Pacific Northwest USA

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dc.contributor.author Pearl, Christopher A.
dc.contributor.author Adams, Michael J.
dc.contributor.author Bury, R. Bruce
dc.contributor.author Wente, Wendy H.
dc.contributor.author McCreary, Brome
dc.date.accessioned 2011-01-14T19:24:23Z
dc.date.available 2011-01-14T19:24:23Z
dc.date.issued 2009 en_US
dc.identifier.uri https://hdl.handle.net/10535/6801
dc.description.abstract "Amphibian declines have been reported in mountainous areas around the western USA. Few data quantify the extent of population losses in the Pacific Northwest, a region in which amphibian declines have received much attention. From 2001–2004, we resurveyed historical breeding sites of two species of conservation concern, the Western Toad (Bufo [=Anaxyrus] boreas) and Cascades Frog (Rana cascadae). We detected B. boreas breeding at 75.9% and R. cascadae breeding at 66.6% of historical sites. When we analyzed the data using occupancy models that accounted for detection probability, we estimated the current use of historically occupied sites in our study area was 84.9% (SE = 4.9) for B. boreas and 72.4% (SE = 6.6) for R. cascadae. Our ability to detect B. boreas at sites where they were present was lower in the first year of surveys (a low snowpack year) and higher at sites with introduced fish. Our ability to detect R. cascadae was lower at sites with fish. The probability that B. boreas still uses a historical site for breeding was related to the easting of the site (+) and the age of record (-). None of the variables we analyzed was strongly related to R. cascadae occupancy. Both species had increased odds of occupancy with higher latitude, but model support for this variable was modest. Our analysis suggests that while local losses are possible, these two amphibians have not experienced recent, broad population losses in the Oregon Cascades. Historical site revisitation studies such as ours cannot distinguish between population losses and site switching, and do not account for colonization of new habitats, so our analysis may overestimate declines in occupancy within our study area." en_US
dc.language English en_US
dc.subject drought en_US
dc.subject amphibians en_US
dc.subject lakes en_US
dc.title Evaluating Amphibian Declines with Site Revisits and Occupancy Models: Status of Montane Anurans in the Pacific Northwest USA en_US
dc.type Journal Article en_US
dc.type.published published en_US
dc.type.methodology Case Study en_US
dc.coverage.region North America en_US
dc.coverage.country United States en_US
dc.subject.sector Water Resource & Irrigation en_US
dc.subject.sector Wildlife en_US
dc.identifier.citationjournal Diversity en_US
dc.identifier.citationvolume 1 en_US
dc.identifier.citationpages 166-181 en_US

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