Brood Patches of American Kestrels Altered by Experimental Exposure to PCBs

Abstract

Captive breeding (n = 25 pairs) and nonbreeding (n = 25) American kestrels were exposed to a mixture of polychlorinated biphenyls (PCBs) (Aroclor 1248:1254:1260) through their diet of day-old cockerels. Kestrels ingested approximately 7 mg/kg body weight each day of PCBs, and this dosage resulted in environmentally relevant total PCB residues in eggs (geometric mean of 34.1 μg/g). An equal number of unexposed birds served as controls. Bare areas of skin known as brood patches function during incubation to warm eggs; therefore, brood patch size could potentially influence hatching success, or patches may be a confounding factor in the relationship between poor incubation behavior and hatching failure observed in birds in toxicological studies. Exposure to PCBs altered the size of brood patches in American kestrels. PCB-exposed male and female nonbreeders had two of three brood patches that were larger than those of control nonbreeders. Breeding males exposed to PCBs had smaller patches than controls, whereas PCB-exposed female kestrels had one larger and one smaller patch than controls. Patch sizes were not related to total PCB residue levels in eggs of exposed birds. Brood patches were not related to various incubation behaviors or hatching success in either control or PCB-exposed kestrels.

The authors thank Jerry Huff for developing the electronic balance and Ian Ritchie for his management and knowledge of the American kestrels at the Avian Science and Conservation Centre. S. A. Fisher thanks the University of Saskatchewan for financial support through a graduate fellowship. K. J. Fernie thanks the University of Saskatchewan for financial support through the Isabel María López Martínez Memorial Scholarship. This study was funded by the National Sciences and Engineering Research Council (to G. R. Bortolotti and J. E. Smits) and the Canadian Network of Toxicology Centres (to G. R. Bortolotti and J. E. Smits).

Notes

Note. Values are mean ± SD. Values marked with superscript a are significantly different (p < .05) from those marked with b for the comparison of PCB-exposed and CTL kestrels for each patch variable within each gender and status group as summarized from the text.

Fisher, S. A. 2002. Courtship behaviour, incubation behaviour and brood patches of America kestrels (Falco sparverius) exposed to polychlorinated biphenyls. MSc thesis, University of Saskatchewan, Saskatoon, Saskatchewan, Canada