Tails of enticement: caudal luring by an ambush-foraging snake (Acanthophis praelongus, Elapidae)

摘要

Ambush foragers that attract prey via luring provide an opportunity to examine how a predator's behaviour influences its dietary composition.Australian death adders (Acanthophis praelongus, Elapidae) are heavy-bodied ambush foragers with broad diets; the snake's modified tail-tip is waved to attract prey. Female adders have shorter tails than males, but longer terminal spines.We videotaped captive snakes interacting with potential prey items (lizards and frogs) to document which prey types elicit luring, and which respond by approaching the lure. To clarify prey responses, we controlled lure size and colour by attaching snake tails (removed from dead adders) to a machine that waved the tail-tip in a manner similar to a live snake.Individual adders differed in luring behaviour, and the type of tail-tip movement (undulatory vs. straightline) influenced rates and duration of luring bouts.Lure movement was essential to attract lizards, and small lures were more effective than larger ones; the greater effectiveness of small lures may explain why caudal luring tends to be more common in juvenile snakes than in larger conspecifics.Death adders lured more vigorously to lizards than to frogs, and lizards were more likely to approach the lure. Thus, luring in death adders mostly enables these snakes to capture lizards; frogs (also an important dietary component in the field) must be caught another way.An ambush predator's overall dietary composition, as well as ontogenetic changes in that composition, thus depend upon both lure characteristics and prey responses.