An assessment of environmental enrichment on morphology and behavior of yearling rat snakes (Elaphe obsoleta)

by 1974- Almli, Lynn M.

Behavioral consequences of differential experience relating to studies of environmental enrichment have been documented primarily in mammals and birds. Similar data on experience-dependent behavioral plasticity are lacking in other vertebrates, especially non-avian reptiles. This project examined whether environmentally induced change occurs in snakes. Specifically, I housed rat snakes, Elaphe obsoleta, in enriched and standard environments to determine if differential experience can alter body morphology and improve behavioral abilities. Rat snakes are a particularly good model for this type of experiment because they are typically solitary and live in a complex three-dimensional habitat. After being housed in different conditions for eight months, 16 E. obsoleta were measured and behaviorally tested in a feeding task, exploratory task, and a learning task. The results of this study demonstrate that housing condition, including feeding regime, can alter the morphology and behavior of captive snakes. In particular, snakes raised in enriched environments were larger (in mass and snout-vent length) and had increased growth rates as compared to controls. In a feeding task with live prey, snakes raised in enriched environments had shorter consumption times, suggesting increased foraging efficiency. In an exploratory task, snakes raised in enriched environments had higher initial tongue flick scores per trial and habituated more quickly to repeated exposures to the open field as compared to controls. Additionally, snakes raised in enriched environments maintained shorter latencies to the goal hole in a learning task, demonstrating superior learning ability as compared to control snakes, though neither group improved over the few trials conducted. iii