Bald eagle, Haliaeetus leucocephalus

Bowman, Tim

Bald eagles (Haliaeetus leucocephalus) occur only in North America and are widely distributed along coastlines and inland waterways throughout the United States, Canada, and northwest Mexico. Their habitats include everything from arctic tundra to arid deserts to mangrove swamps. Currently, highest densities are along the coasts of Alaska and British Columbia and may reach up to about one nest per mile of shoreline in some areas. Bald eagles were once perceived as competitors with people for fish and game and subjected to widespread persecution. For example, claims by fox farmers and fishermen of eagle depredations prompted the Alaska Territorial legislature to impose a bounty system on eagles in 1917. From 1917 until the bounty system was removed in 1953, bounty hunters tallied 128,000 eagles in Alaska and probably many more were shot but never recovered. Bald eagles also were subject to the effects of contaminants, most notably the pesticide DDT, which was used in some Lower 48 states from 1947 to 1972 to control mosquitoes. DDT bioaccumulated in the food chain. Eagles foraging on contaminated food were themselves contaminated with DDT and failed to lay eggs or produced eggs with thin eggshells, which broke during incubation. Consequently, eagle populations plummeted in the Lower 48 states. Populations there were listed as endangered in 1967 and afforded additional protection under the Endangered Species Act in 973. "Endangered" means a species is considered in danger of extinction throughout all or a large part of its range, whereas "threatened" means a species is considered likely to become endangered but is currently not in danger of extinction. They have made a remarkable comeback in the past two decades due to reintroduction programs, intensive management, the ban on DDT use in the U.S., and habitat protection. Bald eagles were reclassified from endangered to threatened in 1995. Unlike bald eagles in the Lower 48 states, bald eagles in Alaska were never listed under the Endangered Species Act , and their populations have remained relatively healthy, despite the fact that they were hunted for bounties until 1953.