SPATIAL ECOLOGY OF SNAPPING TURTLE (CHELYDRA SERPENTINA) WITHIN AN URBAN WETLAND COMPLEX
thesisposted on 22.11.2021, 16:38 by Zachary Robert KelloggZachary Robert Kellogg
The conversion of natural habitat to urban areas has lasting impacts on wildlife and biodiversity. Known effects to urban wildlife include direct mortality while crossing roads, reduced species diversity, and habitat fragmentation and degradation. Among wildlife occupying urban areas, turtle populations can be particularly impacted in anthropogenic landscapes. Snapping Turtle (Chelydra serpentina) is one of the most common species found within urban wetlands, but populations are beginning to show declines in northern portions of their geographic range. The preservation and management of this species is aided by knowledge related to its spatial ecology. I investigated C. serpentina home range, movement, habitat use, and habitat selection in a midwestern USA urban wetland complex during two active seasons (May-August 2019 and 2020) using radiotelemetry. Home range sizes and movement did not differ between sex or sample year except the mean movement of males decreased from 2019 to 2020. No differences in mean monthly movement were found between sexes but mean monthly movement did differ between month and year. Habitat use was skewed during the active season and did not differ between sex or year, but there were positive habitat associations between forested wetlands and modal centers of activity (MCA). Habitat selection was tested at two spatial scales by comparing random points to home ranges and turtle locations using Euclidean Distance Analysis. Turtles appeared to select home ranges from available habitat site-wide but did not select habitat within home ranges. Home range selection included semi-permanent open water, trail, road/barrier, permanent open water, scrub-shrub, ditches, shoreline, and vegetated ponds, while upland forest, field and agriculture habitat were avoided. Home ranges appear to be constrained by available habitat and movement differences between years may be due to anthropogenic change in water levels. The use of space seems to be more affected by wetland size and connectivity than proximity to barriers, which suggests that management practices that protect turtles from accessing roads and railways will benefit populations. Additionally, habitat selection and association indicate that ditches are utilized as corridors between wetland areas. When feasible, increasing the connectivity of large wetlands containing many habitat types should have positive impacts on the persistence of populations in human dominated landscapes.