To help them soar, eagles use thermals which are rising currents of warm air and up-drafts 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." (Courtesy of Marybeth Garrigan)
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 interlocking of feathers is an astonishing design of nature.
Birds puff up their feathers for various reasons. They puff them up while preening; to insulate themselves to changing temperatures; when they're relaxed; to make themselves appear larger when threatened; and when they're ill.
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 acquire available food supplies.
Eagles molt in patches, taking almost half a year to replace feathers, starting with the head and working downward. Not all feathers are replaced in a given molt.
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.
Bald eagles are active during daylight hours (diurnal).
Fidelity - Once paired, bald eagles remain together for life; although if one dies the survivor will not hesitate to accept a new mate.
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.
Respiratory system - Eagles have an external naris on both sides of their 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 breath cycle - twice that of mammals.
More about the respiratory system of birds
Immature bald eagle
Bald eagles are larger than golden eagles in average height and wingspan, but there isn't much difference in average weight. One way to distinguish a golden eagle from an immature bald eagle is leg plumage. A golden eagle's legs are entirely feather covered; an immature bald eagle's lower legs are bare. As seen while in flight, juvenile golden eagles have white patches at the base of the primaries; the tail is white with a distinct dark terminal band. It takes four years to acquire adult plumage. Adult golden eagles are brown with tawny on the back of the head and neck; tail faintly banded.
Until 1995, the bald eagle had been listed as endangered under the Endangered Species Act in 43 of the 48 lower states, and listed as threatened in Wisconsin, Minnesota, Michigan, Washington and Oregon. In July of 1995, the US Fish and Wildlife Service upgraded the status of bald eagles in the lower 48 states to "threatened."
On June 28, 2007 the Department of Interior took the American bald eagle off the Endangered Species List. The bald eagle will still be protected by the Migratory Bird Treaty Act and the Bald and Golden Eagle Protection Act. The Bald Eagle Protection Act prohibits the take, transport, sale, barter, trade, import and export, and possession of eagles, making it illegal for anyone to collect eagles and eagle parts, nests, or eggs without a permit. Native Americans are able to possess these emblems which are traditional in their culture.
Page 1 of bald eagle description information
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