Monday, January 17, 2011

Black-Billed Magpie

With their large size, bold pied plumage, and fondness for open areas, black-billed magpies are easily seen. They hop and walk on the ground with a swaggering and confident gait. Monotypic. Length 19" (48 cm).
Identification An unusually long-tailed black-and-white corvid with a black bill. In good light, black on wings and tail shine with iridescent green, blue, and violet. Juvenile has milky grayish-colored iris and fleshy pinkish gape. The upperparts are washed dull brownish, and the belly is more cream-­colored. Immatures have narrower and more pointed outer tail feathers. Flight: relatively slow, with steady, rowing wingbeats, but the birds are easily able to quickly change direction in flight. Magpies usually swoop up or down to perch.


Geographic Variation While monotypic, birds in the south average smaller and tend to show bare dark grayish skin below eye (similar in shape to the yellow skin on yellow-billed magpie).
Similar Species Black bill and range distinguish this species from the yellow-billed magpie; larger size of the black-billed magpie sometimes appreciable in the field. Until recently, the black-billed magpie was lumped with the wide­spread magpie (Pica pica) of Eurasia and northwestern Africa, but all evidence suggests a much closer relationship with the yellow-billed.


Voice Quite varied, but most vocalizations are rather harsh. All are very similar to that of the yellow-billed magpie. They are strikingly faster and lower pitched than Old World populations of magpie. Call: frequently gives a whining, rising mea; sometimes these are more drawn out and questioning: meeaaah. Also a quickly repeated shek-shek-shek with each phrase repeated 3–5 times (not as harsh or piercing as analogous vocalization of Steller’s jay).


Status and Distribution Common. Resident of open woodlands and thickets in rangeland and foothills; nests along watercourses and other areas with trees and shrubs, but foraging birds use very open areas. Migration and Dispersal: generally considered to be nonmigratory, but varies regionally and by year. Dispersing flocks form as early as July and typically consist of a few to a hundred birds; occasionally forms flocks of several hundred. Movements may be upslope, downslope, or in any direction. Banding recoveries have shown atypical movements of more than 500 km. Most birds are thought to return near where they hatched to breed. Vagrant: casual to Pacific coast, western Wisconsin, Iowa, and northern Texas, mostly in fall. In summer found north as far as northern Alaska, northeastern Northwest Territories. Other sightings occur casually throughout the East and may pertain to escaped cage birds.
Population Declined throughout the Great Plains with the slaughter of bison and targeted eradication. Adapting and now found in many suburban areas.
—From the National Geographic book Complete Birds of North America, 2006