Meeting Abstract
Red-eared slider turtles (Trachemys scripta elegans) are native to the southeastern United States, but have successfully colonized locations all over the world through human introduction via the international pet trade. Like many reptiles, T. s. elegans is highly sensitive to developmental environments, most notably to temperature due to temperature-dependent sex determination. Thus, the microhabitat that females choose for nesting can have important effects on development, particularly in areas outside of its native range. In this study, we quantified the consequences of maternal nest site choice at a site in Portland, OR, which contains one of the most northern invasive populations. During May and June 2016, we located slider nests and transplanted half the eggs to randomly selected ‘nest’ sites in order to determine the consequences of maternally-chosen nest microhabitats. At each nest, we measured several microhabitat variables, including distance to water, slope of nest, water content of nest soil, nest temperature, and canopy openness. This project is still underway, but preliminary analyses show that mothers choose nesting locations with significantly less shade cover than expected at random. Nest slope and distance from water did not differ between maternally-chosen and randomly-selected nests. In September, we will return to the study site to collect hatchlings and assess egg mortality, offspring sex ratio, and morphometrics. We predict that maternally-selected nest microhabitats will result in reduced egg mortality and a relatively balanced sex ratio compared to randomly-selected microhabitats. Overall, our results will provide insights into adaptive nesting behaviors in invasive populations, and will provide a better understanding of how competition for nest sites might impact native turtle species that utilize the same nesting habitat as T. s. elegans.
