One egg was removed from five Wood Stork (Mycteria americana) nests at each of eight colonies in central and northern Florida in 1982. DDE and mercury were present in all eggs with concentrations ranging up to 9.4 and 0.73 ppm wet weight, respectively. PCBs were detected in 25 eggs (63%) with a high value of 3.5 ppm. Other organochlorine compounds occurred in less than 30% of the eggs. Contaminant concentrations were remarkably similar among colonies. Overall, DDE and PCB concentrations were significantly less (P < 0.05) in Wood Stork eggs collected in Florida in 1982 vs. those collected in 1973. DDE was negatively correlated with eggshell thickness (r = -0.48 P <.0.01). Eggshell thickness was greater in 1982 than it was during the period 1967-73 (P.< 0.09) but was still 4.3% less than in eggs collected before 1947 (P < 0.05). Eggs from nests with less than 100% hatching success were linked with higher DDE concentrations (2.92 ppm vs 1.01; P = 0.09), but contaminants showed no significant link to fledging success. Although it is possible that a few individuals may have been affected by DDE, we found no evidence that organochlorine pesticides, PCBs, or mercury were significantly depressing Wood Stork populations.
Additional publication details
Contaminants in wood stork eggs and their effects on reproduction, Florida, 1982