Prey records indicate that the Eastern Indigo Snake (Drymarchon couperi) is a dietary generalist; however, we know little about diet selectivity of this imperiled species. In this study, we investigated dietary preferences using a sample of neonate Eastern Indigo Snakes (N = 55) from 11 clutches by assaying responses to chemical cues from several potential prey species. Specifically, we explored predatory response to cues from a mammal and representatives of two subfamilies of snakes (Colubrinae and Crotalinae). Snakes were presented with chemical cues of potential prey and preference was assessed using a tongue flick attack score using a repeated-measures design.
We found that Eastern Indigo Snakes exhibited a significant overall preference for snakes over house mice (Mus musculus; P < 0.0001), and a significant preference for Copperheads (Agkistrodon contortrix) over Ratsnakes (Pantherophis spiloides; P < 0.0001). Our results demonstrate prey discrimination in Eastern Indigo Snakes and a preference for ophidian prey. Importantly, our findings indicate crotaline snakes may be a principal dietary component of wild populations. This information increases our understanding of the natural history of Eastern Indigo Snakes, the focus of numerous conservation and repatriation projects.