Ecology of the snapping turtle (Chelydra serpentina) in an urban river

Kevin M McLane, Purdue University

Abstract

As urban development spreads across the landscape, understanding the impacts of anthropogenic disturbances on native wildlife is becoming increasingly important. Rivers may be particularly impacted, not only from alteration of the river itself, but also the surrounding landscape and the quality of the water. River turtles may provide insight as indicator species of overall river function and impacts, given their long lifespans, potentially large population density, and preference of habitats that are at a greater risk of anthropogenic disturbance. The study of spatial ecology in urban habitats has increased, helping to improve habitat management and aid conservation efforts for species of concern. Using radio telemetry and geographic information systems (GIS), I characterized the habitat use and spatial ecology of a local Snapping Turtle (Chelydra serpentina) population in an urban river environment. Snapping Turtles from the St. Joseph River in Fort Wayne, Indiana were monitored during their active summer months to characterize habitat preference and movement patterns. They were also located in the winter to identify overwintering sites. Snapping Turtles were found to have range lengths between 209 and 2047 m for females and between 143 and 1268 m for males. Mean movement distances were 165 m (± 37 m) for females and 113 m (± 16 m) for males. There was no significant difference found between sexes, years, or size in movement patterns. There was no significant difference in upland habitat associations from the expected associations. Turtle locations were more frequently associated with higher levels of detritus than was expected, but no significant differences were observed in associations with woody structure levels or substrate type. Hot spot analysis revealed a pattern of significant spatial clusters around shallow inlets across years and sexes. One turtle was recorded crossing a dam which altered its home range size and movement patterns. Turtles were observed moving extensive distances of up to 1.5 km in a single 24 hour period, but no overland movements were observed. The findings from this work expand on our knowledge of turtle behavior in urban settings and help guide land use practices for rivers in Indiana and beyond by stressing the importance of maintaining river buffer zones and shallow inlet habitats along the river. The effects of the dam observed in this study beg the consideration of installing culverts or paths that turtles can use to travel back and forth from either side of a dam.

Degree

M.S.

Advisors

Kingsbury, Purdue University.

Subject Area

Wildlife Management|Ecology|Behavioral Sciences

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