Summary

The Colombian slider, Trachemys callirostris (Family Emydidae), is a moderate-sized turtle (carapace length to 33 cm) endemic to northern South America, with two recognized subspecies: T. c. callirostris in northern Colombia and northwest Venezuela, and T. c. chichiriviche further east along the Venezuelan coast. The two subspecies are distinguished by various aspects of their coloration and the structure of the second neural bone. There also may be differences in adult sizes, with T. c. callirostris being atypically small for a tropical slider turtle, but this may reflect the intense hunting pressures nesting females of this subspecies experience in most areas of its distribution. Trachemys callirostris is sexually dimorphic, with females being larger. While different populations may differ in mean body size, morphometric and genetic studies have provided no evidence for significant intra-specific variation besides the morphological differences between the two subspecies. These turtles are habitat generalists, omnivores, and bask frequently, but little else concerning their demography or non-breeding ecology is known. Nesting occurs during the dry season (December–May) and eggs are usually buried under low vegetation in moist soil near the shoreline. Clutch size depends on female size, and varies from 1–23 eggs. Predation on eggs and egg incubation failure is common. A study of incubation temperatures in natural nests found that with a mean incubation temperature of 31.7°C, all neonates produced were females, implying the species has temperature-dependent sex determination. Adults and nests are exploited throughout the range of the species, and despite protection by national legislation and the existence of several protected areas within the range of the species, current levels of exploitation probably are not sustainable. Enforcement of existing legislation and demographic monitoring are needed.