Trends in Rocky Mountain amphibians and the role of beaver as a keystone species

Biological Conservation
By: , and 



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 (Anaxyrus 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.

Study Area

Publication type Article
Publication Subtype Journal Article
Title Trends in Rocky Mountain amphibians and the role of beaver as a keystone species
Series title Biological Conservation
DOI 10.1016/j.biocon.2015.05.005
Volume 187
Year Published 2015
Language English
Publisher Elsevier
Contributing office(s) Northern Rocky Mountain Science Center
Description 9 p.
First page 260
Last page 269
Country United States
Online Only (Y/N) N
Additional Online Files (Y/N) N
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