Reproductive and morphological effects of o,p'-dicofol on two generations of captive American kestrels.

A two-generation laboratory study was conducted on a captive population of American kestrels (Falco sparverius) to investigate the possible reproductive and teratogenic effects of the pesticide dicofol. Paired females were exposed to three levels of dicofol: 0, 5, and 20 mg/kg. Integrity of the reproductive tract of the resulting embryos was examined. Viable eggs were hatched, and these birds were permitted to breed the following year. Breeding performance for these birds was measured based on their ability to form pair bonds and exhibit normal behavior in the presence of a mate. Clutch completion, fertility, hatchability, and number of hatchlings reared to the fledging were used as reproductive parameters. Females dosed with 20 mg/kg of dicofol laid eggs with shells that were significantly (p < 0.05) thinner than those of the control birds. Residue levels of dicofol in the form of dichlorobenzophenone were detected in the first and second clutch eggs of the 20-mg/kg dose group only. Male embryos from females dosed with 5 and 20 mg/kg of dicofol had gonads that were significantly different (p < 0.05) from the control chicks. Feminization of male embryos was confirmed by the presence of primordial germ cells in the male gonad. Second-generation adult 5-mg/kg females showed a significantly (p < 0.05) greater number of eggs and hatched chicks lost when compared to second-generation control females. Similar results were found in second-generation 5-mg/kg males paired with normal females and had a significant (p < 0.05) number of chicks die posthatching. Results of second-generation breeding parameters indicate a negative effect on reproductive behavior.