Bald Eagle Survival and Population Dynamics in Alaska after the "Exxon Valdez" Oil Spill

• Published in: The Journal of wildlife management 1995-04, Vol.59 (2), p.317-324
• Main Authors: Bowman, Timothy D., Schempf, Philip F., Bernatowicz, Jeffrey A.
• Format: Article
• Language: English
• Subjects: Animal nesting; Animal populations; Animal, plant and microbial ecology; Applied ecology; Aves; Biological and medical sciences; Birds; Birds of prey; Brackish; Breeding; Eagles; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on vertebrates; Fundamental and applied biological sciences. Psychology; Haliaeetus leucocephalus; Marine; Oil spills; Ornithology; Population dynamics; Population growth; Population growth rate; Shorelines; Survival; Survival rates
• ISSN: 0022-541X; 1937-2817
• DOI: 10.2307/3808945

We investigated age-specific annual survival rates for 159 bald eagles (Haliaeetus leucocephalus) radiotagged from 1989 to 1992 in Prince William Sound (PWS), Alaska. We monitored radio-tagged eagles for ≤3 years beginning 4 months after the Exxon Valdez oil spill. There was no difference (P > 0.10) in survival rates between eagles radiotagged in oiled areas and eagles radiotagged in unoiled areas of PWS. Pooled annual survival rates were 71% for first-year eagles, 95% for subadults, and 88% for adult bald eagles. Most deaths occurred from March to May. We found no indication that survival of bald eagles radiotagged >4 months after the oil spill in PWS was directly influenced by the spill and concluded that any effect of the spill on survival occurred before eagles were radiotagged. A deterministic life table model suggests that the PWS bald eagle population has an annual finite growth rate of 2%. Given the cumulative effects of direct mortality and reduced productivity caused by the oil spill, we predicted that the bald eagle population would return to its pre-spill size by 1992.