Courtship Behavior of Captive American Kestrels (Falco sparverius) Exposed to Polychlorinated Biphenyls

Polychlorinated biphenyls (PCBs) adversely affect reproduction in birds. Captive adult male and female American kestrels (Falco sparverius) were studied to investigate the potential behavioral and hormonal alterations during the courtship period resulting from clinical exposure to PCBs. American kestrels ingested 7 mg/kg/body weight/bird/day of a 1:1:1 mixture of Aroclors 1248, 1254, and 1260 through their diet of day-old cockerels. The dietary dosage of Aroclors resulted in environmentally relevant total PCB residues in the eggs, averaging 34.1 μg/g wet weight (geometric mean). There was no difference between treatment and control birds in the circulating levels of total androgens (p = 0.44) or in 17β-estradiol (p = 0.29), one week following pairing. Male kestrels exposed to dietary PCBs exhibited significantly more sexual behaviors (p = 0.034) and flight behaviors (p = 0.026) than the control males. Sexual behaviors of male kestrels included; nest-box inspections, solicitation of copulation, the offer of food to the female, and giving the female food. The flight behaviors of the male included; flying from one perch to another and aerial display. In addition, the frequency of male sexual behaviors were correlated (r = 0.605, p = 0.001) with total PCB residues in the eggs of their mates. A concurrent study found that these same PCB-exposed kestrels experienced a delay in clutch initiation as well as a greater number of completely infertile clutches. Received: 22 September 2000/Accepted: 19 March 2001