Foraging Strategies of American Kestrels During Breeding

Of the two hunting methods most commonly used by American Kestrels (Falco sparverius), hovering cost more but yielded more per unit time perch—hunting. Birds increased their use of hovering relative to other hunting methods as wind speed increased (lowering the energetic cost of hovering flight), and as the number and size of their dependents rose. Perch—hunting kestrels left a foraging site shortly after reward rate fell below the average reward rate for all sites, a behavior consistent with maximizing net energy intake when travel costs are considered. Larger prey were preferentially transported to the mate or young, as predicted by central place foraging models. In three pairs, males provides females during egg—laying, incubation, and brooding, but one pair foraged individually and shared incubation. Each pair foraged in ways that minimized the costs of energy acquisition in its particular situation.