Sky Watch

by Nava Thompson

Title

Sky Watch

Artist

Nava Thompson

Medium

Photograph - Photography

Description

A photo taken by Nava Thompson of a Bald Eagle in Bella Vista Arkansas in the early spring.................................. 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..................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..................... 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..........................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..........................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 the fact that the immature bird has a black beak with a yellow tip, while the mature eagle has a fully yellow beak..................The Bald Eagle has sometimes been considered the largest true raptor (accipitrid) in North America. The only larger species of raptor-like bird is the California Condor (Gymnogyps californianus), a New World vulture which today are not generally considered a taxonomic ally of true accipitrids.[7] However, the Golden Eagle, averaging 4.18 kg (9.2 lb) and 63 cm (25 in) in wing chord length in its American race (A. c. canadensis), is merely 455 g (1.00 lb) lighter in mean body mass and exceeds the Bald Eagle in mean wing chord length by around 3 cm (1.2 in).[5][8] Additionally, the Bald Eagle's close cousins, the relatively longer-winged but shorter-tailed White-tailed Eagle and the overall larger Steller's Sea Eagle (H. pelagicus), may rarely vagrate to coastal Alaska from Asia.................... A recording of a Bald Eagle at Yellowstone National Park....................The Bald Eagle has a body length of 70�102 centimeters (28�40 in). Typical wingspan is between 1.8 and 2.3 m (5.9 and 7.5 ft) and mass is normally between 3 and 6.3 kilograms (6.6 and 14 lb).[5] Females are about 25% larger than males, averaging 5.6 kg (12 lb), and against the males' average weight of 4.1 kg (9.0 lb).[2][9][10][11] 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). Similarly small, eagles from South Carolina average 3.27 kg (7.2 lb) in mass and 1.88 m (6.2 ft) in wingspan.[12] 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][13] A survey of adult weights in Alaska showed that females weighed on average 6.3 kg (14 lb) and males weighed 4.3 kg (9.5 lb).[14] Among standard linear measurements, the wing chord is 51.5�69 cm (20.3�27 in), the tail is 23�37 cm (9.1�15 in) long, and the tarsus is 8 to 11 cm (3.1 to 4.3 in).[5][15] The culmen reportedly ranges from 3 to 7.5 cm (1.2 to 3.0 in), while the measurement from the gape to the tip of the bill is 7�9 cm (2.8

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September 7th, 2013

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