A rare predator exploits prey escape behavior:: the role of tail-fanning and plumage contrast in foraging of the painted redstart (Myioborus pictus)

Escape response, triggered by an approaching predator, is a common antipredatory adaptation of arthropods against insectivores. The painted redstart, Myioborus pictus, represents insectivorous birds that exploit such antipredatory behaviors by flushing, chasing, and preying upon flushed arthropods. In field experiments I showed that redstarts evoke jump and flight in prey by spreading wings and tail: this display increased frequency of aerial chases by redstarts. Artificial models with spread tails also elicited escape responses more often than models with closed tails and wings. The white patches on black wings and tails additionally help: the frequency of chases decreased when the white patches were covered with black dye. Black models also tended to elicit escape response less often than black-and-white models did, at least in some situations. Hence, the prey's ability to detect birds and to flee could cause the evolution of predators specialized at using conspicuous behavior and contrast in body coloration to elicit and exploit such antipredatory responses. Redstarts constitute only a small proportion of the predatory guild, and their adaptations to exploit the prey's behavior illustrate the theoretically modeled "rare enemy" effect present in multispecies predator-prey systems. This is the first experimental study of morphological and behavioral adaptations of a rare predator that both elicits and exploits antipredator escape behavior of its prey against more common predators. Hence, the study documents a behavior that could be evolutionarily explained only if indirect interactions in predator-prey communities are taken into account.