Greater Yellowstone Network Amphibian and Wetland Monitoring: Status Report for 2014, 2015, and 2016

Patla, Debra; Ray, Andrew

National parks in the Greater Yellowstone Ecosystem (Grand Teton National Park, John D. Rockefeller, Jr. Memorial Park-way, and Yellowstone National Park) provide an opportunity to monitor amphibians and wetlands within a relatively intact ecosystem and at spatial and temporal scales that offer valuable insights about changing wetland conditions and amphibian population dynamics. The Greater Yellow-stone Network amphibian and wetland monitoring program conducts annual surveys of potential amphibian breeding habitat in randomly selected watershed units of Grand Teton and Yellowstone national parks. Amphibians were selected in 2005 as an indicator of biological integrity under the Vital Signs program. The principal goal of the program is to track changes in the distribution and occurrence of breed-ing amphibians in wetlands of Yellowstone and Grand Teton national parks. Annually, we estimate occupancy rates and the dynamics of wetland breeding sites. Annual measures of amphibian occurrence and wetland flooding status contrib-ute to local, regional, and national level trends analysis of amphibian populations and their habitat. This work, when combined with historical data, will provide managers and the public with information on a class of native fauna and on wetland characteristics that are important for understanding long-term trends and climate-induced changes to wetlands. This report describes amphibian monitoring efforts and results from the years 2014, 2015, and 2016. In these 3 years, we conducted surveys in 31 catchments (sampling units) se-lected for long-term monitoring. All 4 native species targeted for long-term monitoring were found within the catchments: Western Tiger Salamander (Ambystoma mavortium), Western Toad (Anaxyrus boreas), Boreal Chorus Frog (Pseudacris maculata), and Columbia Spotted Frog (Rana luteiventris). The Plains Spadefoot (Spea bombifrons), confirmed as a resi-dent of Yellowstone in 2013, was not found in the long-term monitoring catchments, but we provide some information rom informal monitoring at a known breeding site in 2016. The Northern Leopard Frog (Lithobates pipiens), which was historically present in Grand Teton National Park, was not encountered. Likewise, the nonnative American Bullfrog (Lithobates catesbeianus), which is known to occupy 1 area of Grand Teton National Park, was not detected at any moni-tored sites. Monitoring in 2014–2016 determined that the year 2014 was an unusually productive year, with record-high catchment occupancy rates for 3 species: Western Tiger Salamander, Boreal Chorus Frog, and Columbia Spotted Frog. Catchment occupancy declined progressively over the next 2 years (2015 and 2016) for these same 3 species. The year 2014 was also notable for the total number of active amphibian breeding sites (all species combined), which was much higher in com-parison to the number of breeding sites detected in previous years with similar levels of effort. The number of detected breeding sites for Boreal Chorus Frogs and Columbia Spot-ted Frogs decreased from 2014 to 2015, followed by partial recovery in 2016. Western Tiger Salamander breeding sites, always found less often than the frog species, did not follow a similar pattern—2015 emerged as the year with the largest number of detected breeding sites. Western Toad breeding sites showed little change in the scant sample obtained from catchment monitoring or from the informal monitoring. Observations of mass migration by Western Toads along a stream corridor in Grand Teton National Park increased our understanding of management impacts on this species of conservation concern. The percent of monitoring sites that were dry and thus unavailable for amphibian breeding was relatively low in 2014, followed by sharp increases in 2015 and 2016. This pattern was driven by distinct annual meteo-rological conditions: 2014 was relatively cool and wet while 2015 and 2016 were warm and dry across our sample frame.

Greater Yellowstone Network Amphibian and Wetland Monitoring: Status Report for 2014, 2015, and 2016

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