Population Demographics of Native Red-Bellied Cooters and Invasive Red-Eared Sliders in a Virginia Lake

Abstract. An 8-wk mark-and-recapture study using baited fyke nets showed that native red-bellied cooters (Pseudemys rubriventris) (estimated population 738–3618) were more abundant than non-native red-eared sliders (Trachemys scripta elegans) (estimated population 256–520) in Lake Matoaka in southeastern Virginia. Red-bellied cooters have maintained a similarly large population since a prior study in 2004 with a balanced female:male sex ratio of 0.91:1, but over that time, capture of red-eared sliders has increased almost 5-fold; their size distribution is broader than that of red-bellied cooters, and their sex ratio is dominated by females (2.02:1). Persistence of native red-bellied cooters in Lake Matoaka may be challenged by the apparent ongoing growth of the invasive red-eared slider population.