Trends in Rocky Mountain Amphibians and the Role of Beaver as a Keystone Species

Authors: Blake R Hossack; W R Gould; Debra A Patla; Erin Muths; R Daley; K Legg; P. Stephen Corn
Contribution Number: 510
Abstract/Summary

Despite prevalent awareness of global amphibian declines, there is still little information on trends for many widespread species. To inform land managers of trends on protected landscapes and identify potential conservation strategies, we collected occurrence data for five wetland-breeding amphibian species in four national parks in the U.S. Rocky Mountains during 2002–2011. We used explicit dynamics models to estimate variation in annual occupancy, extinction, and colonization of wetlands according to summer drought and several biophysical characteristics (e.g., wetland size, elevation), including the influence of North American beaver (Castor canadensis). We found more declines in occupancy than increases, especially in Yellowstone and Grand Teton national parks (NP), where three of four species declined since 2002. However, most species in Rocky Mountain NP were too rare to include in our analysis, which likely reflects significant historical declines. Although beaver were uncommon, their creation or modification of wetlands was associated with higher colonization rates for 4 of 5 amphibian species, producing a 34% increase in occupancy in beaver-influenced wetlands compared to wetlands without beaver influence. Also, colonization rates and occupancy of boreal toads (Anxyrus boreas) and Columbia spotted frogs (Rana luteiventris) were ≥2 times higher in beaver-influenced wetlands. These strong relationships suggest management for beaver that fosters amphibian recovery could counter declines in some areas. Our data reinforce reports of widespread declines of formerly and currently common species, even in areas assumed to be protected from most forms of human disturbance, and demonstrate the close ecological association between beaver and wetland-dependent species.

Publication details
Published Date: 2015
Outlet/Publisher: Biological Conservation
Media Format: .PDF

ARMI Organizational Units:
Rocky Mountains, Southern - Biology
Rocky Mountains, Northern - Biology
Topics:
Drought; Monitoring and Population Ecology; Species and their Ecology
Place Names:
Colorado; Glacier National Park; Grand Teton National Park; Montana; Rocky Mountain National Park; United States; Wyoming; Yellowstone National Park
Keywords:
amphibians; ARMI; climate; colonization; detection; drought; extinction; habitat; habitat effects; habitat use; hydroperiod; monitoring; occupancy; pond-breeding amphibians; population; trends; water; wetlands; wilderness
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