Amphibian and Bird Communities of Lake Ontario Coastal Wetlands: Disturbance Effects and Monitoring Efficiencies

Abstract

Anthropogenic disturbance has become a major topic of study in recent years. As human populations and development have increased, anthropogenic disturbance has led to the loss or conversion of many habitat types, including forests, wetlands, prairies, and grasslands. One major ecosystem negatively affected by anthropogenic disturbance is wetlands. Lake Ontario, within the Laurentian Great Lakes of North America, has seen major development of wetlands and wetland-associated landscapes. Development in wetlands and nearby areas can lead to habitat loss and population declines of wetland-dependent species. My two-part study examined 1) effects of anthropogenic disturbance surrounding Lake Ontario coastal wetlands on anuran and bird communities, and 2) effectiveness of the Great Lakes Coastal Wetlands Monitoring Program (GLCWMP) methods for monitoring birds and anurans in Lake Ontario wetlands. In the first part of my study, I used six variables to represent anthropogenic disturbance and modelled the effects on species richness and abundance for birds and anurans. I found that wetland area was a significant predictor for increased bird species richness in wetlands, while increased levels of nitrogen, phosphorus, and chloride were significant predictors of decreased anuran species richness. This could be due to the permeability of anuran skin which allows for the increased movement of chemical compounds into organisms, causing mortality or decreased breeding success in many anurans. Further, increased agricultural land surrounding wetlands was a 2 significant predictor for increased anuran species richness, which could be due to some anuran species using upland habitats post-breeding. In the second part of my study, I visited sites monitored for birds and anurans under the GLCWMP more frequently than the current methods require. I compared the richness counts between the two site visits required for bird monitoring and three site visits required for anuran monitoring under the GLCWMP with my more intensive surveys. I found that for both anurans and birds, species richness increased with the number of visits to a site. My first study supports the need for monitoring anuran species in Lake Ontario wetlands, due to disturbance. Increased nutrients from roadside runoff and agricultural land use is negatively affecting anurans. Bird species showed no negative effects from my disturbance variables, but several disturbance-tolerant species were observed in most counts. My second study supports increasing the number of visits to sites for better species richness estimates and individual species detections at individual wetlands.