Assessing amphibian species in wetlands in an urban-rural matrix

Background/Question/Methods

Amphibians are unique since they occupy both terrestrial and aquatic habitats, usually breeding in wetlands, rendering them useful indicators of ecosystem health. Amphibian numbers have been declining for several years with multiple species placed on the endangered species list. Habitat loss and fragmentation resulting from urbanization and changing land uses are major factors leading to these declines. The primary goals of this study are to do the following: assess amphibian presence/relative abundance/diversity in various wetland types of northwest Ohio, identify important local and landscape variables, determine if land use affects amphibian presence/relative abundance/diversity, determine the age assemblage of salamander populations, and determine what specific terrestrial areas amphibians are using. This past field season we monitored ten sites using frog call surveys to assess anuran presence, relative abundance, and diversity. Sites were monitored two to three times, for a three minute period, beginning at least one-half hour after sunset. Five sites were monitored once by funnel trapping. Traps were placed in the early afternoon and checked the following morning. We measured percent ground cover (via 1mx1m quadrats) and percent canopy cover (by photograph) every 20m along the perimeter of the water body.

Results/Conclusions

We detected six of the ten anuran species historically present in northwest Ohio. Funnel trapping indicated the highest abundance of anurans (327) at the site with the highest probability of dispersal.  Preliminary results indicate a significant, negative correlation between species diversity of calling frogs and percent canopy cover (p=0.0042) and a positive relationship between species diversity and percent ground cover. Species diversity was not correlated with water area, distance to nearest road, or distance to nearest stream/creek. This research should help us better understand the patterns of diversity and abundance of amphibians in this mixed land use matrix and the landscape factors that influence these patterns.