Date of Award

8-2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Forestry and Environmental Conservation

Committee Member

Dr. Kyle Barrett, Committee Chair

Committee Member

Dr. Beth Ross

Committee Member

Dr. Cathy Jachowski

Abstract

Recent literature suggests that several North Carolina bog turtle (Glyptemys muhlenbergii) populations are in decline, and many of these populations have few remaining individuals with low annual survival probability. Most populations appear dominated by older adults with few juveniles encountered; however, the proportion of juveniles encountered at two populations is dramatically higher. The reason for this variability is unknown. We conducted a nest monitoring study in 2016 and 2017 to test the hypothesis that nest survival patterns explain the observed population age structure. We collected the largest dataset yet compiled on the fate of naturally-incubated bog turtle eggs as well as the first study of its kind in North Carolina. Predation was the primary driver of nest failure across all sites. Populations with more juvenile encounters had substantially higher egg survival. These observations support the hypothesis that variation in egg survival may be linked to observed variation in recruitment patterns. We subsequently incorporated site-specific population parameters, including site-specific egg survival, into a stage-based matrix model to estimate population growth rates and to assess potential management scenarios for five bog turtle populations. Only two of the five populations modeled were stable or growing under current vital rates. Our results demonstrated that management scenarios targeting increased recruitment (especially a head-start scenario) may substantially contribute to some populations reaching stability. Population growth rates will likely be higher when recruitment augmentation coincides with wetland restoration efforts that increase survival and site fidelity at other life stages.

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