Fascinating Bald Eagle Facts

The bald eagle is the national bird as well as national animal of the United States of America. It's a uniquely North American eagle, ranging from northern Mexico through all of the contiguous United States, into Canada and Alaska. The only state the bird doesn't call home is Hawaii. The eagle lives near any open body of water, preferring a habitat with large trees in which it builds is nests.

Description

Bald eagles are not actually bald—by adulthood, they have white-feathered heads. In fact, the bald eagle's scientific name, Haliaaetus leucocephalus, translates from the Greek to mean "sea eagle white head."

Immature eagles (eaglets) have brown plumage. Adult birds are brown with a white head and tail. They have golden eyes, yellow feet, and hooked yellow beaks. Males and females look the same, but mature females are about 25% larger than males. An adult eagle's body length ranges from 70 to 102 cm (28 to 40 in), with a wingspan of 1.8 to 2.3 m (5.9 to 7.5 ft) and a mass of 3 to 6 kg (6.6 to 13.9 lb).

It can be challenging to identify a distant bald eagle in flight, but there is an easy way to tell an eagle from a vulture or hawk. While large hawks soar with raised wings and turkey vultures hold their wings in a shallow V-shape, the bald eagle soars with its wings essentially flat.

The sound of a bald eagle is somewhat like a gull. Their call is a combination of high-pitched staccato chirps and whistles. Believe it or not, when you hear the sound of a bald eagle in a movie, you're actually hearing the piercing cry of the red-tailed hawk.

Diet and Behavior

When available, the bald eagle prefers to eat fish. However, it will also eat smaller birds, bird eggs, and other small animals (e.g., rabbits, crabs, lizards, frogs). Bald eagles choose prey that is unlikely to put up much of a fight. They'll readily drive off other predators to steal a kill and will eat carrion. They also take advantage of human habitation, scavenging from fish processing plants and dumps.

Eagle-Eye Vision

Bald eagles truly have eagle-eye vision. Their vision is sharper than any human's, and their field of view is wider. In addition, eagles can see ultraviolet light. Like cats, the birds have an inner eyelid called a nictitating membrane. Eagles can close their main eyelids, yet still see through the translucent protective membrane.

Reproduction and Offspring

Bald eagles become sexually mature at four to five years of age. Ordinarily, the birds mate for life, but they will seek new mates if one dies or if the pair repeatedly fails at breeding. The mating season occurs in the autumn or spring, depending on location. Courtship includes elaborate flight, which includes a display in which the pair flies high, locks talons, and falls, disengaging just prior to striking the ground. Talon-clasping and cartwheeling may occur during territorial battles, as well as for courtship.

Bald eagle nests are the largest and most massive bird nests in the world. A nest may measure up to 8 feet across and weigh up to a ton. Male and female eagles work together to build a nest, which is made of sticks and is usually situated in a large tree.

The female eagle lays a clutch of one to three eggs within 5 to 10 days of mating. Incubation takes 35 days. Both parents care for the eggs and the downy gray-colored chicks. An eaglet's first true feathers and beak are brown. Fledgling eagles transition to adult plumage and learn to fly great distances (hundreds of miles per day). On average, a bald eagle lives about 20 years in the wild, although captive birds have been known to live 50 years.

Swimming Ability

Eagles are known for soaring in the skies, but they fare well in water, too. Like other fish eagles, the bald eagle can swim. Eagles float well and flap their wings to use them as paddles. Bald eagles have been observed swimming at sea and also near shore. Near land, eagles elect to swim when carrying a heavy fish.

Conservation Status

In 1967, the bald eagle was listed as endangered under the Endangered Species Preservation Act. In 1973, it was listed under the new Endangered Species Act. The dramatic population decline that led to near-extirpation included unintentional poisoning (mostly from DDT and lead shot), hunting, and habitat destruction. By 2004, however, bald eagle numbers had recovered enough that the bird was listed in the IUCN Red List as "least concern." Since that time, bald eagle numbers have continued to grow.

Sources

• del Hoyo, J., Elliott, A., & Sargatal, J., eds.. Handbook of the Birds of the World Vol. 2. Lynx Edicions, Barcelona, 1994. ISBN 84-87334-15-6.
• Ferguson-Lees, J. and D. Christie,. Raptors of the World. London: Christopher Helm. pp. 717–19, 2001. ISBN 0-7136-8026-1.
• Isaacson, Philip M. The American Eagle (1st ed.). Boston, MA: New York Graphic Society, 1975. ISBN 0-8212-0612-5.