Conditioning in garter snakes: Aversion to palatable prey induced by delayed illness

Gaiter snakes (Thomnophis sirtalis) accustomed to a fish diet were injected with either saline or lithium chloride 30 min following the ingestion of earthworms. On subsequent tests at 4-day intervals, the LiCl-injected snakes showed significantly increased attack latencies to worms, which were often refused, but not to fish. Behavioral observation of feeding and concurrent tests with surface substance extracts of worm and fish indicate that chemosensory mediation is involved.