Surplus killing and caching by American kestrels ( Falco sparverius)

Abstract

On all eight trials while free in the laboratory, a male American kestrel ( Falco sparverius) killed and deposited more than one prey (surplus killing), which were presented one at a time. When confined in a smaller enclosure he displayed surplus killing only once in five trials. Two wild female F. sparverius displayed surplus killing of white mice thrown sequentially from a moving car. Some mice were cached, as defined by a pushing movement. The male consistently ate the surplus prey; one female ate white mice on subsequent days and at least one prey deposited by the second female was absent the next day. Since the kestrels utilized some of the prey, it is suggested that surplus killing with caching might be adaptive.