Changes in Reproductive Courtship Behaviors of Adult American Kestrels (Falco sparverius) Exposed to Environmentally Relevant Levels of the Polybrominated Diphenyl Ether Mixture, DE-71

Abstract

Polybrominated diphenyl ethers (PBDEs) are increasing in biota. Here, captive adult American kestrels were exposed daily by diet to safflower oil (controls), or one of two levels of a pentaBDE technical formulation, DE-71 (0.3 or 1.6 ppm), for approximately 75 days, commencing 21 days before breeding. This exposure resulted in eggs having PBDE concentrations similar (low exposure) or within the same order of magnitude (high exposure) reported for wild American kestrels and gulls in the Great Lakes. Compared to controls, kestrels in both exposure groups copulated less, spent less time in their nest boxes, and participated in fewer pair-bonding behaviors. Furthermore, the timing of these behaviors, which is important to creating and maintaining the pair-bond, also differed significantly from the controls. The females in the low-exposure group made fewer compatible trilling calls and ate less frequently. These behavioral changes were compounded by increasing exposure to DE-71 during the 9-day courtship period immediately preceding egg laying, a standard measure of the kestrel courtship period. The birds in the high-exposure group made more food transfers, excited "klee" calls, and copulations, the latter only when compared to the low-exposure birds, whereas the low-exposure males performed fewer pair-bonding behaviors. This study demonstrates that the exposure of kestrels to environmentally relevant levels of DE-71 modifies the quality of the pair-bond, affects the reproductive behavior of both sexes, and occurs when birds are exposed for a short period as adults. In addition, these behavioral effects are consistent with the observed reproductive changes in these birds.