Bald Eagle

The Bald Eagle (Haliaeetus leucocephalus Greek hali = salt, aeetus = eagle, leuco = white, cephalis = head) is a bird of prey found in North America. It is the national bird of the United States of America and appears on its Seal. This sea eagle has two known sub-species and forms a species pair with the White-tailed Eagle. Its range includes most of Canada and Alaska, all of the contiguous United States, and northern Mexico. It is found near large bodies of open water with an abundant food supply and old-growth trees for nesting. Its diet consists mainly of fish, but it is an opportunistic feeder. It hunts fish by swooping down and snatching them out of the water with its talons. It is sexually mature at four years or five years of age. The Bald Eagle builds the largest nest of any North American bird, up to 4 meters (13 ft) deep, 2.5 meters (8.2 ft) wide, and one metric ton (1.1 tons) in weight.

The adult Bald Eagle is mainly brown with a white head and tail. The sexes are identical in plumage, but females are larger than males. The beak is large and hooked. The plumage of the immature is brown. Bald Eagles are not actually bald, the name derives from the older meaning of the word, "white headed".
In the late 20th century the Bald Eagle was on the brink of extirpation in the continental United States, while flourishing in much of Alaska and Canada. Populations recovered and stabilized, so the species was removed from the U.S. federal government's list of endangered species and transferred to the list of threatened species on July 12, 1995, and it was removed from the List of Endangered and Threatened Wildlife in the Lower 48 States on June 28, 2007.

Additionally, the Bald Eagle's close cousins, the longer-winged but shorter-tailed White-tailed Eagle and the overall larger Steller's Sea Eagle, may rarely vagrate to coastal Alaska from Asia.[6] At any rate, the Bald Eagle is certainly a large bird, with a body length of 70–102 centimeters (28–40 in). The wingspan is typically between 1.8 and 2.3 m (5.9 and 7.5 ft) and mass is usually between 3 and 6.3 kilograms (6.6 and 14 lb).[6] Females are about 25 percent larger than males, averaging 5.8 kg (13 lb), and against the males' average weight of 4.1 kg (9.0 lb).

The size of the bird varies by location and generally corresponds with Bergmann's rule, since the species increases in size further away from the Equator and the tropics. The smallest specimens are those from Florida, where mature males may weigh as little as 2.3 kg (5.1 lb) and have a wingspan of 1.68 m (5.5 ft). The largest eagles are from Alaska, where large females may weigh up to 7.5 kg (17 lb) and span 2.44 m (8.0 ft) across the wings.[4][9] Among standard linear measurements, the wing chord is 51.5–69 cm (20.3–27 in), the tail is 23–37 cm (9.1–15 in) long, and the tarsus is 8 to 11 cm (3.1 to 4.3 in). The culmen reportedly ranges from 3 to 7.5 cm (1.2 to 3.0 in), while the measurement from the gape to the tip of the bill is 7–9 cm (2.8–3.5 in).

Description

The plumage of an adult Bald Eagle is evenly brown with a white head and tail. The tail is moderately long and slightly wedge-shaped. Males and females are identical in plumage coloration, but sexual dimorphism is evident in the species in that females are 25 percent larger than males. The beak, feet and irides are bright yellow. The legs are feather-free, and the toes are short and powerful with large talons. The highly developed talon of the hind toe is used to pierce the vital areas of prey while it is held immobile by the front toes. The beak is large and hooked, with a yellow cere.

The plumage of the immature is brown, speckled with white until the fifth (rarely fourth, very rarely third) year, when it reaches sexual maturity. Immature Bald Eagles are distinguishable from the Golden Eagle in that the former has a more protruding head with a larger beak, straighter edged wings which are held flat (not slightly raised) and with a stiffer wing beat, and feathers which do not completely cover the legs. The Bald Eagle has sometimes been considered the largest true raptor in North America, excluding the California Condor, which is a member of the New World vultures and may not be a true accipitrid. However, the Golden Eagle, in its American race, broadly overlaps in body weight and overall size with the Bald Eagle.