Zeus - Alaskan Bald Eagle

Name : Zeus

Sex : Male

Species : Alaskan Bald Eagle - Haliaeetus leucocephalus

Hatch Date : 21-04-2012

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.

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. 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. 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). 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. 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 cm (3.1 in) on average. The culmen reportedly averages 5 to 6 cm (2.0 to 2.4 in), while the measurement from the gape to the tip of the bill is 7–9 cm (2.8–3.5 in).

The Bald Eagle prefers habitats near seacoasts, rivers, large lakes, oceans, and other large bodies of open water with an abundance of fish. Studies have shown a preference for bodies of water with a circumference greater than 11 km (7 mi), and lakes with an area greater than 10 square kilometers (4 sq mi) are optimal for breeding Bald Eagles.

The Bald Eagle requires old-growth and mature stands of coniferous or hardwood trees for perching, roosting, and nesting. Selected trees must have good visibility, an open structure, and proximity to prey, but the height or species of tree is not as important as an abundance of comparatively large trees surrounding the body of water. Forests used for nesting should have a canopy cover of no more than 60 percent, and no less than 20 percent, and be in close proximity to water.

The Bald Eagle is extremely sensitive to human activity, and is found most commonly in areas free of human disturbance. It chooses sites more than 1.2 km (0.75 mi) from low-density human disturbance and more than 1.8 km (1.1 mi) from medium- to high-density human disturbance. Occasionally Bald Eagles will venture into large estuaries or secluded groves within major cities, such as Hardtack Island on the Willamette River in Portland, Oregon or John Heinz National Wildlife Refuge at Tinicum in Philadelphia, Pennsylvania. Despite this sensitivity, a family of Bald Eagles moved to the Harlem neighborhood in New York City in 2010.

The Bald Eagle's natural range covers most of North America, including most of Canada, all of the continental United States, and northern Mexico. It is the only sea eagle endemic to North America. Occupying varied habitats from the bayous of Louisiana to the Sonoran Desert and the eastern deciduous forests of Quebec and New England, northern birds are migratory, while southern birds are resident, remaining on their breeding territory all year. At minimum population, in the 1950s, it was largely restricted to Alaska, the Aleutian Islands, northern and eastern Canada, and Florida.

Bald Eagles will also congregate in certain locations in winter. From November until February, one to two thousand birds winter in Squamish, British Columbia, about halfway between Vancouver and Whistler. The birds primarily gather along the Squamish and Cheakamus Rivers, attracted by the salmon spawning in the area.

It has occurred as a vagrant twice in Ireland; a juvenile was shot illegally in Fermanagh on January 11, 1973 (misidentified at first as a White-tailed Eagle), and an exhausted juvenile was captured in Kerry on November 15, 1987.

The Bald Eagle is a powerful flier, and soars on thermal convection currents. It reaches speeds of 56–70 kilometers per hour (35–43 mph) when gliding and flapping, and about 48 kilometers per hour (30 mph) while carrying fish. Its dive speed is between 120–160 kilometers per hour (75–99 mph), though it seldom dives vertically. It is partially migratory, depending on location. If its territory has access to open water, it remains there year-round, but if the body of water freezes during the winter, making it impossible to obtain food, it migrates to the south or to the coast. The Bald Eagle selects migration routes which take advantage of thermals, updrafts, and food resources. During migration, it may ascend in a thermal and then glide down, or may ascend in updrafts created by the wind against a cliff or other terrain. Migration generally takes place during the daytime, when thermals are produced by the sun.