Amphibian Monitoring in the Greater Yellowstone Network—Project report 2008 and 2009: Yellowstone and Grand Teton National Parks

Patla, Debra; Jean, Cathie

The report for the years 2008-2009 regarding amphibian monitoring in Yellowstone and Grand Teton National Parks. Contains information about methods, including study areas, survey schemes, and data analysis, as well as results such as occupancy and potential breeding areas. The national parks within the Greater Yellowstone Ecosystem (GYE) provide an opportunity tomonitor amphibians within a relatively intact ecosystem, at spatial and temporal scales that canprovide important insights about the status of regional amphibian populations and global declines of amphibians. The Greater Yellowstone Network (GRYN) amphibian monitoring program is the only long-term amphibian monitoring program in the GYE that consistently looks at multiple sites across the ecosystem. The goal of this program is to estimate occupancy rates for the reproductive component of native amphibian species, incorporating the dynamics of wetland sites that provide potential breeding habitat. Annual measures of amphibian occurrence and wetland suitability allow trends in amphibian populations to be considered in context of the available habitat. This work will provide managers and the public with information about the status of a class of native fauna in the Parks and wetland habitat trends that may be strongly related to climate change.Based on visual encounter surveys at 40 and 37 catchments, occupancy rates for 2008 and 2009 are 0.16 and 0.09 for tiger salamanders (Ambystoma mavortium), 0.49 and 0.47 for boreal chorus frogs (Pseudacris maculata), 0.45 and 0.42 for Columbia spotted frogs (Rana luteiventris) and 0.06 and 0.05 for boreal toads (Anaxyrus boreas boreas). The percentage of wetland sites suitable for amphibian breeding increased in response to increases in precipitation in 2008 and 2009 compared to earlier years. No bullfrogs or leopard frogs were detected at any sites. Six new boreal toad breeding sites have been located from 2005 to 2009 as part of the catchment monitoring. Analysis of multi-year trends in amphibian occupancy is in progress, with the intention of completing a paper for publication in 2011.Previous work has stated that 3 amphibian species (Columbia spotted frogs, boreal chorus frogs, and tiger salamanders) are considered common and widespread in Yellowstone and Grand Teton.Based on more sampling across different quality habitat, their occurrence is better stated aswidespread throughout the two parks, but in limited and unevenly distributed suitable wetlandbreeding habitat. The increase in amphibian breeding sites between 2007 and 2008 demonstrates the ability of native amphibians to respond to improved moisture conditions with increased breeding efforts. However, it also suggests their vulnerability if climate change results in extended periods of unrelieved drought, shrinking wetlands, and larger proportions of available water diverted for human uses.

Amphibian Monitoring in the Greater Yellowstone Network—Project report 2008 and 2009: Yellowstone and Grand Teton National Parks

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