|| The bald eagle (Haliaeetus leucocephalus), our national bird, is the only eagle unique to North America. The bald eagle's scientific name signifies a sea (halo) eagle (aeetos) with a white (leukos) head. At one time, the word "bald" meant "white," not hairless. Bald eagles are found throughout most of North America, from Alaska and Canada to northern Mexico. About half of the world's 70,000 bald eagles live in Alaska. Combined with British Columbia's population of about 20,000, the northwest coast of North America is by far their greatest stronghold for bald eagles. They flourish here in part because of the salmon. Dead or dying fish are an important food source for all bald eagles.
Eagles are a member of the Accipitridae family; which also includes hawks, kites, and old-world vultures. Scientists loosely divide eagles into four groups based on their physical characteristics and behavior. The bald eagle is a sea or fish eagle.
There are two subspecies of bald eagles. The "southern" bald eagle, Haliaeetus leucocephalus leucocephalus, is found in the Gulf States from Texas and Baja California across to South Carolina and Florida, south of
40 degrees north latitude. The "northern" bald eagle, Haliaeetus leucocephalus alascanus,
is found north of 40
degrees north latitude across the entire continent. The
largest numbers of northern bald eagles are in the Northwest, especially in Alaska. The "northern" bald eagle is slightly larger than the "southern" bald eagle. Studies have shown that "northern" bald eagles fly into the southern states and Mexico, and the "southern" bald eagles fly north into Canada. Because of these finding, the subspecies of "northern" and "southern" bald eagles has been discontinued in recent literature.
Color - Both male and female adult bald eagles have a blackish-brown back and breast; a white head, neck, and tail; yellow feet, legs and beak; and pale yellow eyes.
Immature bald eagles have a mixture of brown and white feathers, with a black beak and brown eyes in younger birds; some immature bald eagles have more mottling than others. Adult plumage develops when a bald eagle become sexually mature; it takes five years for a bald eagle to attain solid white head and tail feathers. For the first five years they gradually change; the beak turns from black to yellow, the eyes from brown to pale yellow, body feathers from mottled to dark brown, and head and tail feathers from mottled to solid white.
Some bald eagles have leucism, a genetic mutation that affects feather pigment. A leucistic bald eagle can have patches of white feathers on its body and wings; have overall faded or pale feathers; or have overall white feathers. Examples: patches of white feathers and pale feathers
The bald eagle is the only eagle confined to North America. There are no other large blackish-brown birds with a white head and tail in North American.
Size - A female bald eagle's body length varies from 35 to 37 inches; with a wingspan of 79 to 90 inches. The smaller male bald eagle has a body length of 30 to 34 inches; with a wingspan ranging from 72 to 85 inches. An eagle's average weight is ten to fourteen pounds. Northern birds are significantly larger than their southern relatives.
Eagles sit at the top of the food chain, making them more vulnerable to toxic chemicals in the environment, since each link in the food chain tends to concentrate chemicals from the lower link.
A bald eagle's lifting power is about 4 pounds. They do not generally feed on chickens or other domestic livestock, but they will make use of available food sources. Bald eagles will take advantage of carrion (dead and decaying flesh). Because of its scavenger image, some people dislike the bald eagle. Other people do not care for powerful and aggressive birds. Still other people object merely on the grounds that it is a bird of prey, which kills other animals for food.
Voice - Shrill, high pitched, and twittering are common descriptions used for bald eagle vocalizations. Eagles do not have vocal cords. Sound is produced in the syrinx, a bony chamber located where the trachea divides to go to the lungs. Bald eagle calls may be a way of reinforcing the bond between the male and female, and to warn other eagles and predators that an area is defended. Bald eagle audio.
Eyesight - An eagle's eye is almost as large as a human's, but its sharpness is at least four times that of a person with perfect vision.
Skeleton - It weighs about half a pound (250 to 300 grams), and is only 5 or 6 percent of its total weight. The feathers weigh twice that much. Eagle bones are light, because they are hollow. The beak, talons, and feathers are made of keratin.
Habitat - Bald eagles live along the coast and on major lakes and rivers where they feed mainly on fish.
Longevity (life expectancy) - It's possible for bald eagles in the wild to live longer than thirty years, but the average lifespan is fifteen to twenty years. A captive eagle at West Stephentown, NY lived to be at least 48 years old.
Body Temperature - About 106 degrees Fahrenheit (41 degrees Celsius)
Eagles do not sweat, so they need to use other cooling methods such as perching in the shade, panting, and holding their wings away from their body.
Tolerance to cold temperatures - A bald eagle's skin is protected by feathers lined with down. Their feet are cold resistance, consisting of mostly tendon. The outside of the bill is mostly nonliving material, with little blood supply.
Heart rate - When we are checking our eagles at rest their heart rate is between 100-120 beats per minute. When we do their physical exams that rate jumps to 180-250 beats per minute. And when the birds are really stressed, like immediately after an exam involving beak coping & talon trimming it may go as high as 300 beats per minute. Keep in mind the heart rates at rest may be slightly lower for wild birds in better cardiovascular health and the high stress rates slightly higher in wild birds. (Heart rate information courtesy of Dr. Dan Hart, raptor curator at the American Bald Eagle Foundation in Haines, AK.)
|| Beak - The hook at the tip is used for tearing. Behind the hook, the upper mandible, the edge sharp enough to slice tough skin, over laps the lower, creating a scissors effect. A bald eagle's beak is a strong weapon, but is also delicate enough to groom a mate's feathers or feed a small portion of food to a newly hatched chick. The beak of a female eagle is deeper (distance from top to chin) than the beak of a male. The beak and talons grow continuously, because they are made of keratin, the same substance as our hair and fingernails. The beak of a captive eagle is not warn down naturally, so must be trimmed annually.
Talons - Talons are important tools for hunting and defense. Eagles kill their prey by penetrating its flesh with their talons.
Eagles can open and close their talons at will. If an eagle is dragged into the water by a fish too large for the eagle to lift, it is because the eagle refuses to release it. In some cases this is due to hunger.
| Status of the bald eagle - On June 28, 2007 the Department of Interior took the American bald eagle off the Federal List of Endangered and Threatened. Bald Eagle De-listing
Bald eagles will still be protected Under the Bald and
Golden Eagle Protection Act.
The US Fish & Wildlife Service Bald and Golden Eagle Post-De-listing Survey Results.
The number of nesting pairs in the lower 48 United States increased 10-fold, from less than 450 in the early 1960s, to more than 4,500 adult bald eagle nesting pairs in the 1990s. In the Southeast, for example, there were about 980 breeding pairs in 1993, up from about 400 in 1981. The largest concentrations were in the states of Florida and Louisiana. The most recent count of bald eagle nesting pairs in the lower 48 indicates MN, FL, and WI have the largest numbers.
U.S. Fish & Wildlife Service
Estimated Number of Bald Eagle Breeding Pairs US Map (estimates 9,789).
Lead exposure in bald eagles in the Upper Midwest
Page 2 of bald eagle description information: Fidelity, flight, feathers, wings and soaring, maneuvering, flight speed, flight altitude, respiratory system, difference between an immature bald eagle and an immature golden eagle, and more.
North American Bird Photos and Information
The information and photos on this website may be used for student projects as long as neither are placed on other websites. The photographs are copyrighted by Hope Rutledge, the owner and author of the American Bald Eagle Information website, and are NOT available for other websites, photo galleries or commercial use of any kind.