Eggshell thickness and reproduction in American kestrels exposed to chronic dietary lead

American kestrels (Falco sparverius) were randomly paired and fed 0, 10, or 50 ppm metallic lead in their diet from November 1979–May 1980. Lead levels were elevated in bones and livers of birds receiving the treated diets, particularly the 50 ppm treatment group. Differential deposition of lead was noted between males and females, with the highest levels in the females. No adverse effects were evident with respect to survival, egg laying, or initiation of incubation in any treatment group nor was fertility or eggshell thickness affected. Little or no lead was transferred to the egg contents and although lead was present in the shell, the levels were too variable for this to be considered a useful measure of exposure.