Bald Eagle

Haliaeetus leucocephalus (Greek: hals, “the sea;” aetos, “an eagle;” leukokephalos, “white-headed” = “white-headed sea eagle”)
Prepared by: 
Ann Walton
  • Wingspan:  6 – 8 feet
  • Length:  28 – 38 inches
  • Weight:  3 – 6.3 kg.

Adult (males and larger females have same coloration) is dark brown with white head and tail.  The massive bill is yellow.  The immature is dark chocolate brown, with dusky head and tail, and a dark bill.  The juvenile also shows an irregular and undefined blotchy white appearance on underwing and tail until its fourth year; after the first year, there also may be a few white marks on its back and upperwing coverts.  The Bald Eagle flies with deep strokes, and soars on flattened wings; in flight, its head appears massive, and its tail noticeably short.  

 

 

Subspecies: 
recognized, both occurring in U.S. One subspecies, washingtoniensis, ranges from Aleutian Is., Alaska, and Canada to northern U.S; the nominate, leucocephalus, occurs from southern U.S. to northwest Mexico.
Habitat: 
Ranges from tundra, conifer forests, and mountains to mangrove and cypress swamps (Florida), sometimes deserts (Mexico), always preferring these ubiquitous areas near good expanses of water, e.g. coasts, estuaries, rivers, and lakes. In winter, also found in sagebrush and desert far from water.
Feeding: 
Bald Eagles are versatile predators; their diet consists of fish, birds (mainly seabirds and waterfowl), mammals (including sea otters), reptiles, invertebrates, carrion (including road kill, whales, and seals), and garbage. In summer, the prey is mainly fish and water birds; important winter food includes mammals and carrion. Their hunting techniques are also versatile. Bald Eagles hunt from perches, as well as catching even goose-sized birds in mid air. They utilize low level flight, using the cover of hilly terrain, or waves, to achieve the element of surprise. To catch seabirds, the Bald Eagle will soar at great heights, often swooping over 330 feet for the kill. These birds can also be attracted to calls of prey, e.g. sea otters, that are out of visual range (Auditory Hunting). Finally, lesser forms of “hunting” include scavenging from dumps and robbing other birds, such as Osprey, of their catches. The Bald Eagle has even been observed snatching prey from the paws of sea otters as these mammals float on their backs. Pairs of Bald Eagles will hunt together.
Breeding: 
October – April in the South; April – August in the North. Solitary; if environment and food is right, several nests can be sparsely scattered in same area. Long term pairing, maintaining their bond each year with spectacular aerial displays in which the two birds lock talons and tumble downward through the air for great distances. Nest is a gigantic bulky, depressed stick platform, lined with grass, seaweed, or other vegetation, and often becoming 12 feet deep and 7 feet in diameter with repeated use. Nest location varies, depending upon region, and includes cliffs, rock stacks, bushes, dead snags, and in forks or on broken tops of trees (30’ – 80’ high), conifers often preferred. These nest sites are usually chosen on, or near, shorelines, if possible. Clutch is 1 – 3 eggs. Breeding can occur at 4 years of age.
Movements: 
Coastal birds and adults in southern range sedentary. In fall, inland populations migrate south, starting September – October, arriving on wintering grounds in November. In summer, southern fledglings move north towards Canada.
Status: 
Not GLOBALLY threatened. Northern populations in Alaska and western Canada not threatened, and even abundant. Lower Canada, and most of U.S., has seen a reduction in numbers, although years of DDT banning and protection finally gave this southern population boost enough to be removed in 1998 from the endangered list. However, industrial use of heavy metals, as well as continued habitat loss, has slowed the positive population progress so that the Bald Eagle in the U.S. was only officially upgraded to “threatened.”
Political History: 
On July 4th, 1776, the Continental Congress appointed a committee, consisting of Benjamin Franklin, John Adams, and Thomas Jefferson, to “bring in a device for a seal of the United States of America.” Since, historically, the eagle represented Imperial Power, our own Bald Eagle stood out as a strong candidate for the national symbol of America. However, Benjamin Franklin objected to the use of this “seal,” because he felt that the Bald Eagle showed “bad moral character” (It was a scavenger and a thief), and was a “rank coward” (In the East, this eagle apparently was known to retreat when its nest was approached; but this might have been the result of over persecution and hunting, as the more undisturbed western birds did fiercely attack any intruder). Although Benjamin Franklin thought the indigenous turkey was more fitting, on June 20, 1782, Congress approved the magnificently stately Bald Eagle as the symbol of our country.