Bald Eagle

Description:

Bald eagle - he plumage of an adult Bald Eagle is evenly 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 percent 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 plumage of the immature is brown, speckled with white 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 in that the former has a 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.[5] The Bald Eagle has sometimes been considered the largest true raptor in North America (excluding the possibly unrelated California Condor), although the species overlaps in size with the American races of the Golden Eagle.[6] It is certainly a large bird, with a body length of 70–102 centimeters (28–40 in). The wingspan is typically between 1.8 and 2.3 m (5.9 and 7.5 ft) and mass is usually between 2.5 and 7 kilograms (5.5 and 15 lb).[6] Females are about 25 percent larger than males, averaging 5.8 kg (13 lb) and against the males' average weight of 4.1 kg (9.0 lb).[2][7][8] The size of the bird varies by location and generally corresponds with Bergmann's rule, since the species increases in size further away from the Equator and the tropics. The smallest specimens are those from Florida, where mature males may weigh as little as 2.3 kg (5.1 lb) and have a wingspan of 1.68 m (5.5 ft). The largest eagles are from Alaska, where large females may weigh up to 7.5 kg (17 lb) and span 2.44 m (8.0 ft) across the wings.[4] Among standard linear measurements, the wing chord is 51.5–69 cm (20.3–27 in), the tail is 12–19 cm (4.7–7.5 in) long, and the tarsus is 8 cm (3.1 in) on average.[9] The culmen reportedly averages 5 to 6 cm (2.0 to 2.4 in), while the measurement from the gape to the tip of the bill is 7–9 cm (2.8–3.5 in).[10][11] The call consists of weak chirping whistles, harsher and more shrill from young birds than adults.[5]

Habitat:

The Bald Eagle prefers habitats near seacoasts, rivers, large lakes, oceans, and 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 square kilometers (4 sq mi) are optimal for breeding Bald Eagles.[21] The Bald Eagle requires old-growth and mature stands of coniferous or hardwood trees for perching, roosting, and nesting. Selected trees must have good visibility, an open structure, and proximity to prey, but the height or species of tree is not as important as an abundance of comparatively large trees surrounding the body of water. Forests used for nesting should have a canopy cover of no more than 60 percent, and no less than 20 percent, and be in close proximity to water.[21] The Bald Eagle is extremely sensitive to human activity, and is found most commonly in areas free of human disturbance. It chooses sites more than 1.2 km (0.75 mi) from low-density human disturbance and more than 1.8 km (1.1 mi) from medium- to high-density human disturbance.[21] Occasionally Bald Eagles will venture into large estuaries or secluded groves within major cities, such as Hardtack Island on the Willamette River in Portland, Oregon or John Heinz National Wildlife Refuge at Tinicum in Philadelphia, Pennsylvania.[22][23] Despite this sensitivity, a family of Bald Eagles moved to the Harlem neighborhood in New York City in 2010.[24] The Bald Eagle's natural range covers most of North America, including most of Canada, all of the continental United States, and northern Mexico. It is the only sea eagle endemic to North America. Occupying varied habitats from the bayous of Louisiana to the Sonoran Desert and the eastern deciduous forests of Quebec and New England, northern birds are migratory, while southern birds are resident, remaining on their breeding territory all year. At minimum population, in the 1950s, it was largely restricted to Alaska, the Aleutian Islands, northern and eastern Canada, and Florida.[25] Bald Eagles will also congregate in certain locations in winter. From November until February, one to two thousand birds winter in Squamish, British Columbia, about halfway between Vancouver and Whistler. The birds primarily gather along the Squamish and Cheakamus Rivers, attracted by the salmon spawning in the area.[26] It has occurred as a vagrant twice in Ireland; a juvenile was shot illegally in Fermanagh on January 11, 1973 (misidentified at first as a White-tailed Eagle), and an exhausted juvenile was captured in Kerry on November 15, 1987.

Notes:

Spotted on Lake Conroe in the Sam Houston National Forest.