American Bald Eagle Information
American Bald Eagle Description
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 Color - Both male and female adult bald eagles have a blackish-brown back and breast; a white head, neck, and tail; and yellow feet and beak.
Juvenile bald eagles are a mixture of brown and white; with a black bill in young birds. The adult plumage develops when they're sexually mature. It takes about 5 years for their head and tail feathers to gradually turn white.
The bald eagle is the only eagle confined to North America, and there are no other large black birds in North America with white heads and tails.
Size - The female bald eagle is 35 to 37 inches, slightly larger than the male. With a wingspan which varies from 79 to 90 inches. The male bald eagle has a body length from 30 to 34 inches. The wingspan ranges from 72 to 85 inches. Bald eagles weigh from ten to fourteen pounds. Northern birds are significantly larger than their southern relatives.
The golden eagle is larger than the bald eagle in average height and wingspan, but there isn't much difference in their average weight.
Habitat - Bald eagles live along the coast and on major lakes and rivers where they feed mainly on fish.
Longevity (bald eagle's life expectancy) - Wild bald eagles may live as long as thirty years, but the average lifespan is probably about fifteen to twenty years. A captive eagle at West Stephentown, NY lived to be at least 48 years old.
Body Temperature - 102 degrees Fahrenheit (38.8 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. |
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Tolerance to cold temperatures - A bald eagle's skin is protected by feathers lined with down. The feet are cold resistance because they are mostly tendon. The outside of the bill is mostly nonliving material, with little blood supply.
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.
Bald eagles are active during daylight hours (diurnal).
Fidelity - Once paired, bald eagles remain together until one dies. The survivor will not hesitate to accept a new mate.
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.
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.
Detailed diagram of a bird skeleton
 The wings and soaring - An eagle's wings are long and broad, making them effective for soaring. To help reduce turbulence as air passes over the end of the wing, the tips of the feathers at the end of the wings are tapered so that when the eagle fully extends its wings, the tips are widely separated.
To help them soar, eagles use thermals, which are rising currents of warm air and updrafts generated by terrain, such as valley edges or mountain slopes.
Soaring is accomplished with very little wing-flapping, enabling them to conserve energy. Long-distance migration flights are accomplished by climbing high in a thermal, then gliding downward to catch the next thermal, where the process is repeated. Several eagles soaring in a thermal together is described as a "kettle of eagles."
Bald eagles can fly to an altitude of 10,000 feet. During level flight, a bald eagle can achieve speeds of about 30 to 35 mph.
The tail - is very important for flight and maneuvering. While the bald eagle is soaring or gliding in flight, the tail feathers are spread in order to attain the largest surface area and increase the effect of thermals and up-drafts. The tail also helps to brake the eagle when landing and assists in stabilization during a controlled dive or swoop toward prey. The strength of the feathers and the follicles holding the feathers is quite impressive while watching the tail move back and forth and up and down during maneuvers.
 Bald eagles have 7,000 feathers. Eagle feathers are lightweight yet extremely strong, hollow yet highly flexible. They protect the bird from the cold as well as the heat of the sun, by trapping layers of air. To maintain its body temperature an eagle simply changes the position of its feathers. While an eagle suns itself on a cold morning, it ruffles and rotates its feathers so that the air pockets are either opened to the air or drawn together to reduce the insulating effect. Feathers also provide waterproofing and protection, and are crucial for flight.
Feather structure makes pliability possible. Overlapping feathers can form a dense covering, which the birds can open or close at will. The bald eagle has several layers of feathers, each serving a different function. Under the outer layer of feathers is an inner layer of down or smaller feathers. The inter locking of feathers is an astonishing design of nature.
The feathers enable eagles to live in extremely cold environments. Eagles do not have to migrate to warmer areas each year to fulfill temperature requirements, they migrate to available food supplies.
A lone eagle feather is believed to convey great power. North American Indians incorporated the eagle's primaries and tail feathers into their ceremonies and legends. Use of feathers permit.
Respiratory system - Eagles have an external nare opening on both sides of the beak. A bald eagle never reaches speeds that would interfere with normal breathing.  An eagle's lungs and air sac system are adequate for its size. Air moves in through the lungs and on into the air sacs before moving back through the lungs and out again. Air passes through the lungs twice with each breathing cycle - twice that of mammals.
More about the respiratory system of birds
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. An eagle might drown during the encounter with the fish or if it's unable to swim far enough to reach shore.
Above all other birds it is the soaring eagle, with its size and weight, that gives the most abiding impression of power and purpose in the air. It advances solidly like a great ship cleaving the swells and thrusting aside the smaller waves. It sails directly where lesser birds are rocked and tilted by the air currents.
---Edwin Way Teale, "Bird of Freedom," Atlantic Monthly, 1957
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