AMPHIBIAN OCCURRENCE AND WETLAND CHARACTERISTICS IN THE PUGET-SOUND BASIN

We studied the pattern of amphibian distributions within 19 wetlands of the Puget Sound Basin in King County, Washington State from 1988 through 1991. Amphibian richness was compared to wetland size, vegetation classes, presence of bullfrog and fish predators, hydrologic characteristics of water flow, fluctuation, and permanence, and land use. Low velocity flow and low fluctuation were correlated with high species richness. Seasonal persistence of water was unrelated to species richness. Wetland size, distance to other wetlands favorable for breeding, fish and bullfrog predators, and the number of vegetation classes found at a wetland were unrelated to total number of species. Increasing mean water-level fluctuation and percent watershed urbanization were correlated with low species richness. Small and structurally simple wetlands often have high value amphibian habitat, and traditional reliance on wetland size and broad vegetation classes without site-specific studies should be avoided when assessing habitat value for amphibians.