community & regional
Appendix 1. Nongame Issue: Declining Amphibians and Reptiles

Objectives:
To assess amphibian and reptile populations to determine whether declining trends are regional or national, and to propose and evaluate hypotheses to explain declines.

Justification:
Amphibians and reptiles are important components of ecosystems. Many species of amphibians have a complex life cycle with aquatic larvae and terrestrial adults. Population declines may reflect events in either aquatic or terrestrial environments or may integrate across the boundary between environments, making amphibians useful indicators of environmental change.

Large-scale declines of amphibian populations were first noticed among leopard frogs in the upper Midwest in the 1960s. More recently, serious declines have been observed in several anuran amphibians in western North America, and in anurans and salamanders in the East and Southeast. Some of these are now Federally endangered. The National Ecology Research Center has documented that leopard frogs and boreal toads are now absent from most known localities in the central Rocky Mountains.

The causes of most of the amphibian declines have yet to be determined, but anthropogenic contaminants have been implicated in several cases. Because amphibian species that were formerly widespread and abundant are now scarce, there is a clear need to assess the extent and nature of this threat to the biodiversity of North American vertebrates. This information on trends and causes of trends is required if wildlife managers are to prevent species from declining to the point where Federal listing is necessary.

Tasks:

  1. Convene a workshop or symposium to assess available information and plan for future research needs (this may be in conjunction with a meeting on this topic proposed by the National Academy of Sciences). One product of this effort would be a strategy for attacking the seemingly intractable problem of how to determine causes of declines that have already occurred. A second product would be a "white paper" or executive summary describing current knowledge of status of amphibian populations, recent changes and their possible causes.
  2. Expand research on declining amphibians in the West and Midwest, comparing historic and current distributions. Emphasis will be placed on boreal toads, leopard frogs, and spotted frogs (a current candidate for Federal listing). Research will be expanded on population size, survivorship, and recruitment in pond-breeding amphibians. Relating trends in population size to environmental variables will require long-term studies.
  3. Summarize the natural history, status, and conservation recommendations for species considered to be in jeopardy. This involves updating the 1980 Fish and Wildlife Resource Publication 134: Conservation of the Amphibia of North America: A Review. Much of the information is out-of-date and several species need to be added.
  4. To complete a survey of the distribution and abundance of ranid frogs in the Southwest. This group includes several species only recently named that are still poorly known. One southwestern ranid is already a candidate for listing as endangered.
  5. To conduct a pilot study of the status of terrestrial and aquatic salamanders and anurans in the Appalachian Mountains and southeastern lowlands, based on a well-documented data base of known populations.
  6. To initiate studies on changes in abundance of amphibians related to timber harvest in the western United States.

These tasks will capitalize on ongoing research on amphibians by the National Ecology Research Center and provide immediate results and insight into this emerging problem. Reptiles would be added to research efforts in future years.

Submitted by R. B. Bury and P. S. Corn,
National Ecology Research Center, Fort Collins, Colorado
22 November 1989


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