Date of Award

8-8-2017

Degree Type

Thesis

Degree Name

Biology (M.S.)

Department

Biology

First Advisor

Jennifer Moore

Second Advisor

Paul Keenlance

Third Advisor

Alexandra Locher

Academic Year

2016/2017

Abstract

Turtles (Order Testudines) are experiencing global declines largely due to anthropogenic influences such as habitat fragmentation, illegal collection and sales, and the threat of global climate change. Removal of individuals from the adult age-classes means there is now a greater need to understand the survival of neonate and juvenile turtle age-classes. In this study I examined a population of eastern box turtles (Terrapene carolina carolina) at the northern limit of their range in Michigan’s lower peninsula. The objectives of my thesis were 1. to determine the microhabitat factors that influence nestsite selection by female box turtles and how selected microhabitat and environmental factors affect box turtle nest success and 2. create known-fate annual survival estimates for hatchling box turtles through the first year of life. Box turtles select nest sites with a higher percent of bare soil and lower amounts of understory vegetation compared to random sites and avoid nesting on north facing slopes. Larger clutch sizes as well as a lower percent of bare soil at the nest site increased the probability of nest success. Depredation and exposure to suboptimal environmental conditions were the primary sources of neonate mortality from 2013-2015, and annual survival estimates for neonate box turtles predicted survival to decrease through the first year of life with a steep drop in the probability of survival from nest emergence in the fall, before leveling off at 50% for overwintering (day 50 = .503; SE = 0.067), then gradually decreasing again with spring emergence till reaching 0% survival short of the 1 year mark (day 335 = 0.0). Similar studies should be conducted across the geographic range of Eastern Box Turtles to better understand the major threats to the survival of other box turtle populations.

Available for download on Wednesday, August 15, 2018

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