Mercury Concentrations in Tissues of Florida Bald Eagles

• Published in: The Journal of wildlife management 1996-01, Vol.60 (1), p.178-185
• Main Authors: Wood, Petra Bohall, White, John H., Steffer, Anthony, Wood, John M., Facemire, Charles F., Percival, H. Franklin
• Format: Article
• Language: English
• Subjects: Animal nesting; Animal, plant and microbial ecology; Applied ecology; Aves; Biological and medical sciences; Bird nesting; Birds; Birds of prey; Blood; Eagles; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on vertebrates; Feathers; Fish; Freshwater fishes; Fundamental and applied biological sciences. Psychology; Geometric mean; Haliaeetus leucocephalus; Hazardous materials; Liver; Mercury; Wildlife conservation
• ISSN: 0022-541X; 1937-2817
• DOI: 10.2307/3802053

We collected 48 blood and 61 feather samples from nestling bald eagles (Haliaeetus leucocephalus) at 42 nests and adult feather samples from 20 nests in north and central Florida during 1991-93. We obtained 32 liver, 10 feather, and 5 blood samples from 33 eagle carcasses recovered in Florida during 1987-93. For nestlings, mercury concentrations in blood (GM = 0.16 ppm wet wt) and feather (GM = 3.23 ppm) samples were correlated (r = 0.69, P = 0.0001). Although nestlings had lower mercury concentrations in feathers than did adults (GM = 6.03 ppm), the feather mercury levels in nestlings and adults from the same nest were correlated (r = 0.63, P < 0.02). Mercury concentration in blood of captive adult eagles (GM = 0.23 ppm) was similar to Florida nestlings but some Florida nestlings had blood mercury concentrations up to 0.61 ppm, more than twice as high as captive adults. Feather mercury concentrations in both nestlings and adults exceeded those in captive eagles, but concentrations in all tissues were similar to, or lower than, those in bald eagles from other wild populations. Although mercury concentrations in Florida eagles are below those that cause mortality, they are in the range of concentrations that can cause behavioral changes or reduce reproduction. We recommend periodic monitoring of mercury in Florida bald eagles for early detection of mercury increases before negative effects on reproduction occur.