Population trends and extinction of amphibians

Population declines are closely associated with extinction risk, but many r-selected amphibian species show fluctuating population sizes that are difficult to link to overall declines. Green examined 617 time series of population census data from 89 amphibian species to address the relative degree of variance in population sizes and how variation in demographic characteristics and habitat requirements affect extinction risk. In general, higher levels of population variance were observed in large stream-breeding and pond- breeding species relative to terrestrial direct-developing or small stream-breeding species. The population crash rates were 3.1% and 2.2% for pond-breeding frogs and pond-breeding salamanders, respectively; crash rates were negligible for stream-breeding and terrestrial direct-developing species. High population variance was associated with the smallest populations but not with life-history complexity. Species with high levels of population fluctuation and local extinctions might be susceptible to habitat fragmentation.

GREEN, D. M. 2003. The ecology of extinction: population fluctuation and decline in amphibians. Biological Conservation 111:331-343.

Correspondence to: David M. Green, Redpath Museum, McGill University, 859 Sherbrooke Street West, Montreal, Quebec, Canada H3A 2K6; e-mail: david.m.green@mcgill.ca.

Copyright Society for the Study of Amphibians and Reptiles Sep 2003