Tradeoffs between escape behavior and foraging opportunity by the Balearic lizard (Podarcis lilfordi)

Optimal escape theory predicts that prey permit closer approach by predators when fleeing is more costly, but does not predict other aspects of escape such as distance fled or the likelihood of returning to the initial site in the presence or absence of a resource such as food. Because a lizard preparing to feed amy lose the feeding opportunity, optimal escape theory predicts that the lizard should allow a predator to approach closer before fleeing when a stationary food source is present than in its absence. In addition, we predicted that when a predator was nearby, lizards would flee a shorter distance and return more often when food was present than absent. We presented adult males of the omnivorous Balearic lizard, Podarcis lilfordi, with a tethered piece of pear or a pebble of similar size and shape. One of us approached a lizard in a standardized manner, stopping and remaining still when the lizard fled. The other investigator recorded escape and return behaviors. Lizards in the presence of food permitted closer approach before fleeing, fled a substantially shorter distance, and were far more likely to return to the site of stimulus presentation than when a pebble was presented. These findings suggest that prey may alter several aspects of escape behavior to reduce costs due to lost opportunities, and present a likelihood that interspecific variation exists in the combination of aspects of antipredatory behavior that are modified.