Date of Award
Master of Science (MS)
Forestry and Environmental Conservation
Dr. Kyle Barrett, Committee Chair
Dr. Beth Ross
Dr. Cathy Jachowski
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.
Knoerr, Michael Donald, "Hatch Success and Population Modeling for the Critically Endangered Bog Turtle in North Carolina" (2018). All Theses. 2930.