Evaluating the Use of Enclosures to Reintroduce Eastern Indigo Snakes

Abstract

Reintroductions are a common tool used for the conservation of imperiled species worldwide. Use of enclosures to effect soft release of individuals for reintroductions has become commonplace because this technique limits dispersal and increases chances for socializations leading to reproduction. However, no published study has used this technique for snake reintroductions. In this study we examined the efficacy of using enclosures to soft release Eastern Indigo Snakes (Drymarchon couperi) within the Conecuh National Forest, a release site at the northern limit of the geographic range for this species. During 2010 and 2011, 38 Eastern Indigo Snakes were reintroduced using both hard (n = 20) and soft (n = 18) release techniques. The snakes were subsequently tracked using radio telemetry. Data gathered from radio telemetry were then used to evaluate the release techniques. We performed analyses on home range size and emigration rates for hard- and soft-released individuals paired to control for effects of sex and time. We also compared male-female overlap between the two release groups. Further, we examined whether the enclosures affected snake survival. Release type did not affect home range size, but did decrease the rate at which snakes emigrated from the release site. Soft-released male snakes had a higher percentage of overlap with females than hard-released males. Finally, enclosures did not significantly affect survival. Our study indicates that using enclosures on large snake species alters movements in ways that should increase viability of reintroduced populations.