Difference between revisions of "Field Guide/Birds/Haliaeetus leucocephalus"
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The Bald Eagle (Haliaeetus leucocephalus), also known as the American Eagle, is a bird of prey originating in North America, most recognizable as the national bird of the United States. The species was on the brink of extinction late in the 20th century but now has a stable population and is in the process of being removed from the U.S. federal government's list of endangered species.
The bird gets both its common and scientific names from the distinctive appearance of the adult's head. Bald in the English name refers to the white head feathers, and the scientific name is derived from Haliaeetus, the New Latin for "sea eagle," (from the Greek haliaetos) and leucocephalus, the Greek for "white head," from leukos ("white") and kephale ("head").
Range and habitat
The Bald Eagle's natural range includes most of North America, including most of Canada, all of the continental United States, and northern Mexico. Because it was hit hard by widespread use of DDT of the mid-twentieth century it is still slowly recovering its numbers; it can be found in small concentrations throughout the U.S. and Canada, particularly near large bodies of water. The state with the largest resident population is Alaska; out of the estimated 100,000 Bald Eagles on Earth, half live in
Description
An immature bird has speckled brown feathers all over, the distinctive head and body plumage arriving 2–3 years later, before sexual maturity. Their life span is approximately 50 years. Adult females have a wingspan of approximately 2.1 meters (7 feet); adult males have a wingspan of 2 meters (6 feet, 6 inches). Adult females weigh approximately 5.8 kg (12.8 lb), males weigh 4.1 kg (9 lb).
Bald Eagles are protected by two federal laws in the United States: the Eagle Law, which protects Bald and Golden Eagles, and the Migratory Bird Act.
Behavior
Bald Eagles build huge nest platforms out of branches, usually in large trees. Pairs, who mate for life, add material to the nest each breeding season. After several years, the nest may weigh upwards of 450 kg (one thousand pounds).
Bald Eagles that are old enough to breed often return to the area where they were raised. They are more social than many other raptor species: an adult looking for a nesting site is more likely to select a location that contains other breeding Bald Eagles.
Bald Eagles are powerful fliers, and also soar on thermal convection currents. They are long-lived, with reports of birds in captivity living to be 60 years old.
Bald Eagles normally squeak and have a shrill cry, punctuated by grunts. They do not make the "eagle scream" as often shown on television. What many recognize as the call of this species is actually the call of a Red-tailed Hawk dubbed into the film.
When breeding in the tundra biome, where there are no trees, eagles will nest directly on the ground.
Reproduction
Bald Eagles are sexually mature at 4 or 5 years of age. Mated pairs produce between one and three eggs per year, but it is rare for all three chicks to successfully fledge. Both the male and female of the pair take turns sitting on the eggs. The other parent will hunt for food or forage for nest material in the intervening time.
Third chicks are sometimes removed from nests to use in reintroduction programs in areas where the species has died out.
In such programs, the birds are raised in boxes, on platforms in the tree canopy, and fed in such a way that they cannot see the person supplying their food, until they are old enough to fly and find their own.
Diet
The Bald Eagle's diet is varied, including carrion, fish, smaller birds, rodents, and sometimes food scavenged or stolen from campsites and picnics.
To hunt fish, the eagle swoops down over the water and snatches the fish out of the water with its talons. They eat by holding the fish in one claw and tearing the flesh with the other. Eagles have structures on their toes called spiricules that allow them to grasp fish. Osprey also have this adaptation.
Sometimes, if the fish is too heavy to lift, the eagle will be dragged into the water. It may swim to safety, but some eagles drown or succumb to hypothermia.
Eagles and humans
As the symbol of the United States, the Bald Eagle is sought after as a captive bird in that country. Permits are required to keep this species. As a rule, it is a poor bird for public shows, being timid, prone to becoming highly stressed, and unpredictable in nature.This doesn't say anything about humans. It doesn't say if the Bald Eagle is nice to humans or not.
Rare vagrant
This species has occurred as a vagrant once in Ireland. The exhausted specimen was discovered by a national parks worker in a northern heath. Presumably, a storm blew it out to sea, and the bird struggled across the Atlantic Ocean.
National Bird of the US
The Bald Eagle is the national bird of the United States of America. Its national significance dates back to June 20, 1782, when the Continental Congress officially adopted the current design for the Great Seal of the United States including a bald eagle grasping arrows and an olive branch with its talons. Some states had earlier adopted the bird as a symbol; for example New York State did so in 1778.
