Captive fledgling American kestrels prefer to play with objects resembling natural prey

Abstract

Object play may be a mechanism by which young predators acquire skills in manipulating prey, as well as physical strength and endurance. It has also been proposed that fledgling raptors play with live or dead prey if available, but would play with surrogates such as sticks or grass if not. Different objects were offered to captive fledgling American kestrels, Falco sparverius, to test whether they prefer to play with objects resembling prey. Individuals were divided into two groups: those in treatment A were offered mouse mimics, along with one of four objects (large and small pine cones, long and short twigs) which were alternated daily. Individuals in treatment B were offered bottle corks, and the same type of alternative objects as in treatment A. There were no significant differences in the mean number of play instances of birds in each of the two treatments (total of 506 instances). However, fledglings in treatment A played significantly more with the mouse mimics, whereas fledglings in treatment B played with the different objects in proportion to their availability. These results support the hypothesis that young raptors devote a relatively fixed amount of time to object manipulation, and that they prefer to manipulate objects resembling natural prey. The same set of objects were offered to adult American kestrels, but they were never manipulated. This suggests that object play has a function in the maturation of hunting skills of young raptors.