Eggshell thinning and contaminant levels in bald eagle eggs from Arizona, 1977 to 1985

The mean eggshell thickness of 11 eggs of bald eagles (Haliaeetus leuccocephalus) and 21 samples of eggshell fragments (n = 32) collected from 14 nests in Arizona during 1977 to 1985 was 0.539 mm, 8.8% thinner than the pre-1947 (pre-DDT) mean for eggs from southern California and Baja California, Mexico. Eleven eggs analyzed for contaminants contained slightly elevated concentrations of DDE (3.3pmm wet weight) and mercury (0.14 ppm). Productivity of sampled pairs was low but improving. The predictive equations of Wiemeyer et al. (1984) were also verified.