NESTING ECOLOGY AND HABITAT USE OF CHELYDRA SERPENTINA IN AN AREA MODIFIED BY AGRICULTURAL AND INDUSTRIAL ACTIVITY

Habitat loss and pollution have been linked to declines of numerous freshwater turtle species, which are among the most endangered vertebrates in the world. We examined characteristics of nest sites of Common Snapping Turtles (Chelydra serpentina) located in a system modified by agricultural and industrial land use. We compared characteristics of 150 turtle nests and patterns of nest depredation in mercury (Hg) polluted and reference sites. Of the nests found in this study, 90% were located in human disturbed soils: 79% in agricultural fields and 11% in commercial nurseries. In both Hg and reference sites, we found that 52% of all nests were located in high density nesting areas in agricultural fields bordered by a river on three sides, providing novel evidence that river geomorphology could be useful for identifying important nesting areas. We did not observe predation in the reference sites but 66% of nests were destroyed at the Hg polluted sites. We provide a predictive model demonstrating that the same characteristics influence nest-site selection in this modified system as in more intact systems, and are related to solar exposure at the time of nesting. We provide evidence that Common Snapping Turtles are attracted to agricultural areas for nesting, which could influence the fate of nests and/or development of embryos. We also suggest that research is needed to verify the importance of river geomorphology on nesting. Additionally, the high depredation rate of turtle nests containing eggs with Hg contamination suggests that the impacts of dietary Hg on predators of turtle nests merits investigation.