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ANIMAL
OF THE WEEK
Once known as the Siberian tiger because of where it lived, it is now referred to as the Amur, named after the Amur River in Russia where many of these tigers now live. read more >

Northern bald eagle

Scientific name: Haliaeetus leucocephalus alascensis


CLASS: Aves
ORDER: Falconiformes
FAMILY: Accipitridae

FEEDING TYPE: Carnivore
STATISTICS: Length: 34 to 45 inches;  Wingspan: 72 to 96 inches; Weight: 7 to 15 lbs

DESCRIPTION:
Adult bald eagles have a black back and breast. They have a white head, neck, and tail along with yellow feet and bill. In North America there are no other large black birds with white heads and tails. Juvenile bald eagles can be much more difficult to identify, as young birds are a sooty brown color, with adult plumage taking several years to develop. The bill is black in young birds. As in other eagles and most birds of prey, the female bald eagle is slightly larger than the male.

RANGE:
Northern reaches of Alaska and Canada down to northern Mexico.

HABITAT:
Bald eagles generally prefer areas fringing water, such as coasts and lakes, with large trees to roost on. In winter, eagles have been known to frequent arid steppes and deserts that are far from water.

ADAPTATIONS:
Eagles capture fish by extending their talons a few inches below the water's surface. Their excellent eyesight enables them to see their prey a great distance away. Live fish are vulnerable only when near the surface or in shallow water.

Eagles take almost half a year to replace feathers after molting. The molting occurs in patches starting with the head and working downward.

REPRODUCTION/GROWTH:
Bald eagles mate for life, and build huge nests in the tops of large trees near rivers, lakes, marshes, or other wetland areas. Nests are often reused year after year. With additions to the nests made annually, some may reach ten feet across and weigh as much as 2,000 pounds. Although bald eagles may range over great distances, they usually return to nest within 100 miles of where they were raised.

Females normally lay two to three eggs once a year. The nesting cycle is about 20 weeks. The eggs hatch after about 35 days. Young eagles fly within three months, and are on their own about a month later. However, disease, lack of food, bad weather, or human interference kills many eaglets; sometimes only about half will survive the first year.

PREY/PREDATOR:
Prey to human interaction
Predator to fish but will eat birds, mammals and reptiles

STATUS:
In 1967, bald eagles were officially declared an endangered species under a law that preceded the Endangered Species Act of 1973 in all areas of the United States south of the 40th parallel. Federal and state government agencies, along with private organizations, successfully sought to alert the public about the bald eagle's plight and to protect its habitat from further destruction.

The greatest threat to the bald eagle's existence arose from the widespread use of DDT and other pesticides after World War II. DDT was sprayed on croplands throughout the country and its residues washed into lakes and streams. There, it was absorbed by aquatic plants and small animals that were eaten by fish. The contaminated fish, in turn, were consumed by bald eagles. The chemical interfered with the bald eagle's ability to develop strong shells for its eggs.

In addition to the adverse effects of DDT, bald eagles also died from lead poisoning as a result of feeding on hunter-killed or crippled waterfowl containing lead shot and from lead shot that was inadvertently ingested by the waterfowl. The bald eagle was removed from the Endangered Species List in June of 2007. It is currently listed as Least Concern with IUCN. However, it is still federally protected under the Eagle Act.

SPECIAL NOTES:

  • Wildlife experts believe there may have been 25,000 to 75,000 nesting bald eagles in the lower 48 states when the bird was adopted as our national symbol in 1782, and made official in 1787. By the early 1960s there were fewer than 450 bald eagle nesting pairs in the lower 48 states. There are about 40,000 bald eagles in Alaska and none in Hawaii. It is the only eagle confined to North America.
     
  • Some states continue reintroduction efforts. Eaglets used for reintroduction may be captive-hatched or, since usually only two young per nest survive, they may be transferred from a bald eagle nest with a clutch of more than two. These "extra" eaglets are placed in the nest of an adult pair whose own eggs are infertile or fail to hatch. The "foster parents" readily adopt the chicks and raise them as their own.

 

BIBLIOGRAPHY

  1. IUCN Redlist. http://www.iucnredlist.org/details/144341. November 2008
  2. Beebe, Frank L. The Complete Falconer. Blaine, WA: Hancock House Publishers, 1992
  3. Birdlife International. Handbook of the Birds of the World. Volume 2. New world Vultures to Guineafowl. Barcelona, Lynx Edicions, 1994.
  4. Terres, John K. The Audubon Society Encyclopedia of North American Birds. New York, NY: Alfred A. Knopf Inc. Publishers, 1980
     

Published: February 2009

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