Size and Wingspan

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.

Weight

Eagles skeletons weigh about half a pound (250 to 300 grams), and is only 5 to 6 percent of its total weight. The feathers weigh twice as much. Eagle bones are light, because they are hollow. The beak, talons, and feathers are made of keratin. Keratin is fibrous structural protein of hair, nails, horn, hoofs, wool, feathers, and of the epithelial cells in the outermost layers of the skin. The polypeptide chains of keratin are arranged in parallel sheets held together by hydrogen bonding.