Date of Graduation

Spring 2012


Master of Natural and Applied Science in Biology



Committee Chair

Day Ligon


alligator snapping turtle, Macrochelys temminckii, nesting ecology, reintroduction, nest-site selection, temperature-dependent sex determination

Subject Categories



The alligator snapping turtle (Macrochelys temminckii) is a large freshwater species that has experienced population declines throughout much of its range. In an effort to reestablish an extirpated population in southern Oklahoma, adult M. temminckii were released at Tishomingo National Wildlife Refuge in 2007. I investigated several aspects of M. temminckii reproductive biology within this reintroduced population, including nest-site selection, reproductive and nest predation rates, and patterns of temperature-dependent sex determination (TSD) in natural nests. Water depth two meters from the shoreline and percentage ground cover were important factors in nest-site selection. The nest predation rate was 76% when efforts were made to protect nests and the average clutch size in intact nests was 22.4 eggs. The overall sex ratio in 2010 recruits was strongly female-biased (91.8% female) and a strongly skewed population sex ratio may become a serious threat to this reintroduced population if this trend continues. I also developed a technique to reliably estimate clutch size from predated M. temminckii shell fragments which will improve estimates of mean clutch size (and therefore annual fecundity) for the population. The persistence of several adult M. temminckii and evidence of successful reproduction and recruitment are positive signs, but post-release monitoring will need to continue for several more years in order for this reintroduction to be considered a success.


© Jessica Leigh Miller

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