ARMI > Apex Sites

Apex Sites

Apex sites are specific sites or groups of sites where research is being conducted. Research is aimed at answering particular questions about amphibian decline or gathering more detailed information about the dynamics of a particular amphibian population.

FORT

We are monitoring populations of amphibians at three apex sites using capture-recapture methods. Our goal in monitoring populations is to detect fluctuations in population size, sex ratio, survival, and recruitment. Through long-term monitoring, we can also address breeding phenology in relation to elevation, weather, and climate. Other specific questions can be asked about issues such as breeding behavior and use of habitat. We are monitoring boreal toad populations and wood frogs in Rocky Mountain National Park and chorus frogs at Cameron Pass in Northern Colorado.

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Rocky Mountain National Park, CO

While boreal toads (Bufo boreas) were formerly common in Rocky Mountain National Park, in recent years only three known breeding sites existed in the Park. We have been studying a metapopulation made up of 2 of the 3 breeding sites since 1991. We began capture - recapture work on the third population in 2001. In 2003 we located a new, undocumented breeding site in the park and will include this site in more in-depth survey work in 2004. Chytrid fungus is present at 2 of 4 of these sites and is likely contributing to the decline we are observing which includes the probable extirpation of toads from one breeding site. We are currently using visual encounter surveys, capture-recapture methods and radiotelemetry to examine these populations. A second project in progress is an analysis of potential causes of decline using information-theoretic analysis and modeling and population viability assessment by CSU Master's candidate Rick Scherer.

On the west side of Rocky Mountain National Park, we are studying a population of wood frogs (Rana sylvatica). We are using visual encounter surveys, capture-recapture and radio telemetry to examine use of habitat during the breeding season. Wood frogs were recently removed from the Colorado list of threatened species and appear to be doing well in the park. This project is the foundation for a long-term, landscape level investigation that will focus on wood frogs and chorus frogs including capture - recapture methods, genetic studies and telemetry.

Rocky Mountain National Park: Clockwise: Lost Lake, toad telemetry work; Gaskil Pond; Lost Lake. Photographs courtesy of E. Muths, and D. Bailey.

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Northern Colorado

We continue to monitor a population of chorus frogs at a site where data have been collected annually since the 1960s, a project started by Drs. David Pettus and Albert Spencer. We use capture-recapture methods to track population changes over time and automated frog call recording systems to collect data during the breeding season. We have addressed acid precipitation, breeding phenology, and climate at this site. Chorus frogs, although very small (approximately 3 cm snout-vent length) have unique individual spot patterns on their backs. We are currently experimenting with a photographic method for "marking" individuals for capture history comparison.

Lily Pond, apex site in northern Colorado, chorus frogs. Photographs courtesy of E. Muths and L. Hoffman.

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NRMSC

In contrast to study areas in Colorado that have 10 or more years of records of continuous population monitoring, there are no long-term datasets for amphibian populations in the northern Rocky Mountains. The exception is an ongoing study of Columbia spotted frogs at Lodge Creek, Yellowstone National Park. Three other long-term research and monitoring areas have been established in the northern Rocky Mountains since 1999.

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Glacier National Park, MT

Three watersheds in Glacier National Park are monitored annually to track changes in the number of breeding sites of boreal toads (Bufo boreas). These watersheds were selected because they are the only areas in the park where we have discovered large numbers (>20) of boreal toad breeding sites. Long-toed salamanders (Ambystoma macrodactylum) and Columbia spotted frogs (Rana luteiventris), which are common in Glacier National Park, also breed in each of these monitoring areas. Annual monitoring networks of breeding sites will help us establish turnover rates of local populations, information necessary to determine whether amphibians are declining in the region. Declines should be manifested by a loss of populations that exceeds colonization rates.

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Bitterroot Mountains, MT

In 1999, we began monitoring breeding of Columbia spotted frogs, long-toed salamanders, and Pacific treefrogs (Pseudacris regilla) at Lost Horse Creek Marsh in the Bitterroot Mountains of western Montana. We have counted egg masses of Columbia spotted frogs since 1999, and in 2000 began a capture-recapture study of Columbia spotted frogs. Our objectives are to measure annual variation in population size, survival and recruitment, and investigate breeding phenology and development. Egg masses of Columbia spotted frogs are also counted at other sites in the area to monitor the size of the female populations.

Glacier National Park. Photographs courtesy of B. Hossack, C. Walker, and G. Thelen.

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Lodge Creek, Yellowstone National Park, WY

Researchers at Idaho State University have studied and monitored amphibian populations in the Lodge Creek area since 1991. Through a cooperative agreement with USGS, this area became an apex site in 2000. Monitoring at this site allows us to continue research on Columbia spotted frogs that was started in 1953 by herpetologist Dr. Frederick B. Turner. Detailed, long-term information about population characteristics and seasonal habitat use of amphibian populations is rare but very important for amphibian conservation efforts. We monitor breeding sites and conduct distribution surveys through the summer and fall to assess possible changes in habitat use within the study area. To determine adult population size, we will use digital photography to identify individuals and apply mark-recapture population size estimation techniques. Earlier results from this study revealed that piecemeal development of the area around Lodge Creek since the 1950s resulted in an almost 80% decline in Columbia spotted frogs between 1955 and 1995.

We work with park resource managers to implement measures that may help protect this population, such as fencing key areas to exclude horses and retaining woody debris in frog movement corridors. We also use the Lodge Creek study area for educational efforts such as field courses through the Yellowstone Association Institute. The Lodge Creek study area will be featured in a public television documentary on biodiversity and habitat fragmentation that is currently under production by the Natural Heritage Project of the Idaho Museum of Natural History.

Lodge Creek apex site, Yellowstone National Park, Columbia spotted frog. Photographs courtesy of D. Patla.

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National Elk Refuge, Jackson Hole, WY

The first known occurrence of infection of amphibians by chytrid fungus in the northern Rocky Mountains was found in boreal toads on the National Elk Refuge in the summer of 2000. We continue to monitor the area to determine how the disease outbreak is affecting the toad and Columbia spotted frog populations. We plan to continue monitoring reproductive sites to estimate the numbers of egg masses and population size of breeding females, and to search for signs of disease outbreaks.

National Elk Refuge apex site, Columbia spotted frog. Photographs courtesy of D. Patla.

Lost Trail National Wildlife Refuge, Montana, MT

Surveys of potential breeding sites during 2001 and 2002 revealed a large breeding population of boreal toads (Bufo boreas) at Lost Trail National Wildlife Refuge. We suspect this is one of the largest populations known in the Rocky Mountains. B. boreas has experienced severe declines in the southern Rocky Mountains, and is a US Forest Service species of concern in Region 1. Recent surveys of >2000 potential breeding sites throughout the northern Rocky Mountains have found this species at <5% of sites, and surveys in the 1990s revealed that B. boreas was absent from many historic localities. There are few data for comparison, but B. boreas seems less common than indicated in historical accounts and may be experiencing a decline.

We established a long-term capture-recapture program of adult B. boreas at Lost Trail NWR in 2003 in collaboration with US Fish and Wildlife Service biologists to determine population size and trends. The capture-recapture study will complement our annual surveys of breeding sites that are used to determine population status (breeding population present/not detected). Each toad is measured (snout-vent length) and receives a passive integrated transponder (PIT tag) injected dorsally for unique identification. Passive integrated transponder tags are commonly used in amphibians, including in previous studies of B. boreas, and have posed few problems. The potential for tag loss is being evaluated by batch marking all tagged animals in 2003. If numerous batch-marked individuals are later captured that do not have a PIT tag (evidence of a lost tag) we will have to re-evaluate our marking program. Skeletochronology of phalanges will be used to determine age of some breeding individuals. 356 toads were captured and marked at 7 breeding sites in 2003.

Photographs of data collecting at Lost Trail NWR, Boreal Toad, and Dahl Lake. Photographs courtesy of S. Corn.

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