A very large bird, the bald eagle stands about 30-45 inches tall. Adults over 5 years old have a white head, neck and tail, dark brown to black body and yellow bill. Immatures are brown with whitish wing linings and blotches on the underparts. Their head and tail will whiten with each molt as they reach adulthood.
Bald eagles are found along the lakes and rivers of Yellowstone National Park where they perch in nearby trees watching for fish below. The best areas to watch for these majestic birds include Yellowstone River and Lake. Although some adult bald eagles will winter in the park most migrate to lower elevations. During these winter months, look for them, sometimes in groups of five or six along the Yellowstone River north of the park.
In the summer, bald eagles eat mostly fish and waterfowl. Their fishing skills, however, are not as polished as those of the Osprey and they have been watched on numerous occasions harassing these fisher birds until they drop their catch and fly off leaving the fish on the ground for the eagle to scavenge. During winter months they feed primarily on waterfowl and carrion. It is not uncommon to see bald eagles feeding on an elk carcass along side ravens, magpies, golden eagles and coyotes.
In 1995, the U.S. Fish and Wildlife Service downlisted the Bald Eagle from endangered to threatened due to significant population gains made over the last three decades. Certain specific populations, however, are not completely recovered due to heavy metal contamination problems in the Great Lakes region, and habitat encroachment and development problems associated with riparian zones in the desert southwest.
In Yellowstone National Park, a total of 14 eaglets fledged from 26 active nests during 1999. Nest substrate instability, a result of the 1988 Yellowstone wildfires, caused minimal problems for nesting pairs; however, in following decades we expect large numbers of trees to topple to the ground. This will undoubtedly result in nest failure, loss of nest sites, and sudden changes in the locations of nesting territories. Although it has occasionally been documented that Bald Eagles will take over previously occupied Osprey nests, the incidence of takeover appears to be increasing due to the competition for nest sites. In 1999 alone, two previously known Osprey nest sites were occupied by Bald Eagles.