Date Approved

12-2022

Graduate Degree Type

Thesis

Degree Name

Biology (M.S.)

Degree Program

Biology

First Advisor

Dr. Jennifer Moore

Second Advisor

Dr. Eric McCluskey

Third Advisor

Dr. Paul Keenlance

Academic Year

2022/2023

Abstract

Habitat fragmentation and loss, predation, and illegal collection are among the many threats plaguing turtle species worldwide which have caused substantial population declines. In the United States and Canada, approximately 38% of turtle and tortoise species are under significant threat. The wood turtle (Glyptemys insculpta) a freshwater turtle species experiencing declines and in 2023, the U.S. Fish and Wildlife Service will determine if this species should be listed under the Endangered Species Act. We studied the spatial ecology of wood turtles in northwestern Michigan, USA to fill knowledge gaps that exist throughout their geographic range. Between May 2021 and August 2022, we used VHF radiotelemetry to track 21 wood turtles which allowed us to quantify home ranges and movement patterns, assess habitat selection, and evaluate use of restored oak-pine barrens. Across both field seasons, average home range sizes were not statistically different between gravid females (23.92 ± 16.26 ha), non-gravid females (11.24 ± 3.40 ha), males (12.76 ± 5.68 ha), and juveniles (3.69 ± 1.46 ha). Gravid females averaged farther distances from the river (219.03 ± 13.85 m) compared to non-gravid females (64.86 ± 4.65 m), males (58.08 ± 2.77 m), and juveniles (34.82 ± 2.79 m). Differences between this population and others can be attributed to variations in the availability of resources, quality of habitat, and accessibility of nesting grounds which are inconsistent across their range. Turtles selected lowland riparian and aquatic habitats and avoided upland forest and forested slopes which echoes other wood turtle studies. One gravid female nested in the restored oak-pine barrens habitat indicating this management practice may benefit the reproductive success of this population through an expansion of nesting opportunities. The variability we observed across years in home range sizes, movement distances, and habitat selection among sex and reproductive classes within this population, indicates a need for continued monitoring to determine long-term patterns. The use of oak-pine barrens by gravid females both years provides preliminary support that this restoration may benefit this wood turtle population.

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