BALD EAGLE SURVIVAL AND POPULATION-DYNAMICS IN ALASKA AFTER THE EXXON-VALDEZ OIL-SPILL

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 less-than-or-equal-to 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.