American Bald Eagle

Description:

The plumage of an adult Bald Eagle is evenly dark brown with a white head and tail. The tail is moderately long and slightly wedge-shaped. Males and females are identical in plumage coloration, but sexual dimorphism is evident in the species in that females are 25% larger than males.[2] The beak, feet and irides are bright yellow. The legs are feather-free, and the toes are short and powerful with large talons. The highly developed talon of the hind toe is used to pierce the vital areas of prey while it is held immobile by the front toes.[3] The beak is large and hooked, with a yellow cere.[4] The adult Bald Eagle is unmistakable in its native range. The closely related African Fish Eagle (H. vocifer) (from far outside of the Bald Eagle's range) also has a brown body, white head and tail, but differs from the Bald in having a white chest and black tip to the bill.[5] The plumage of the immature is a dark brown overlaid with messy white streaking until the fifth (rarely fourth, very rarely third) year, when it reaches sexual maturity.[2][3] Immature Bald Eagles are distinguishable from the Golden Eagle (Aquila chrysaetos), the only other very large, non-vulturine bird in North America, in that the former has a larger, more protruding head with a larger beak, straighter edged wings which are held flat (not slightly raised) and with a stiffer wing beat and feathers which do not completely cover the legs. When seen well, the Golden Eagle is distinctive in plumage with a more solid warm brown color than an immature Bald Eagle, with a reddish-golden patch to its nape and (in immature birds) a highly contrasting set of white squares on the wing.[6] Another distinguishing feature of the immature Bald Eagle over the mature bird is its black, yellow-tipped beak; the mature eagle has a fully yellow beak.

Habitat:

The Bald Eagle occurs during its breeding season in virtually any kind of American wetland habitat such as seacoasts, rivers, large lakes or marshes or other large bodies of open water with an abundance of fish. Studies have shown a preference for bodies of water with a circumference greater than 11 km (7 mi), and lakes with an area greater than 10 km2 (4 sq mi) are optimal for breeding Bald Eagles.[30] The Bald Eagle typically requires old-growth and mature stands of coniferous or hardwood trees for perching, roosting, and nesting. Tree species reportedly is less important to the eagle pair than the tree's height, composition and location.[31] Perhaps of paramount importance for this species is an abundance of comparatively large trees surrounding the body of water. Selected trees must have good visibility, be over 20 m (66 ft) tall, an open structure, and proximity to prey. If nesting trees are in standing water such as in a mangrove swamp, the nest can be located fairly low, at as low 6 m (20 ft) above the ground.[32] In a more typical tree standing on dry ground, nests may be located from 16 to 38 m (52 to 125 ft) in height. In Chesapeake Bay, nesting trees averaged 82 cm (32 in) in diameter and 28 m (92 ft) in total height, while in Florida, the average nesting tree stands 23 m (75 ft) high and is 23 cm (9.1 in) in diameter.[33][34] Trees used for nesting in the Greater Yellowstone area average 27 m (89 ft) high.[35] Trees or forest used for nesting should have a canopy cover of no more than 60%, and no less than 20%, and be in close proximity to water.[30] Most nests have been found within 200 m (660 ft) of open water. The greatest distance from open water recorded for a Bald Eagle nest was over 3 km (1.9 mi), in Florida.[7] Bald eagle nests are often very large in order to compensate for size of the birds. The largest recorded nest was found in Florida in 1963, and was measured at nearly 10 feet wide and 20 feet deep.[36] In Florida, nesting habitats often consist of mangrove swamps, the shorelines of lakes and rivers, pinelands, seasonally flooded flatwoods, hardwood swamps, and open prairies and pastureland with scattered tall trees. Favored nesting trees in Florida are Slash Pines (Pinus elliottii), Longleaf Pines (P. palustris), Loblolly Pines (P. taeda) and cypress trees, but for the southern coastal areas where mangroves are usually used.[32] In Wyoming, groves of mature cottonwoods or tall pines found along streams and rivers are typical bald eagle nesting habitats. Wyoming eagles may inhabit habitat types ranging from large, old-growth stands of Ponderosa Pines (Pinus ponderosa) to narrow strips of riparian trees surrounded by rangeland.[7] In Southeast Alaska, Sitka Spruce (Picea sitchensis) provided 78% of the nesting trees used by eagles, followed by hemlocks (Tsuga) at 20%.[31] Increasingly, eagles nest in man-made reservoirs stocked with fish.[32]

Notes:

The Bald Eagle is the national bird of the United States of America.[134] The founders of the United States were fond of comparing their new republic with the Roman Republic, in which eagle imagery (usually involving the Golden Eagle) was prominent. On June 20, 1782, the Continental Congress adopted the still-current design for the Great Seal of the United States including a Bald Eagle grasping 13 arrows and a 13-leaf olive branch with its talons.[135][136][137] The Bald Eagle appears on most official seals of the U.S. government, including the Seal of the President of the United States and the Presidential Flag, and in many U.S. federal agency logos. Between 1916 and 1945, the Presidential Flag showed an eagle facing to its left (the viewer's right), which gave rise to the urban legend that the seal is changed to have the eagle face towards the olive branch in peace, and towards the arrows in wartime.[138] Contrary to popular legend, there is no evidence that American "Founding Father" Benjamin Franklin ever publicly supported the Wild Turkey (Meleagris gallopavo), rather than the Bald Eagle, as a symbol of the United States. The origin of this claim is a letter Franklin wrote to his daughter in 1784 from Paris. However, this letter was a criticism of the Society of the Cincinnati in which he stated his personal distaste for the Bald Eagle’s behavior but he does not mention publicly disputing the choice of the Bald Eagle for the Great Seal of the United States. In the letter Franklin states:[4]