red-shouldered hawk

The red-shouldered hawk (''Buteo lineatus'') is a medium-sized buteo. Its breeding range spans eastern North America and along the coast of California and northern to northeastern-central Mexico. It is a permanent resident throughout most of its range, though northern birds do migrate, mostly to central Mexico. The main conservation threat to the widespread species is deforestation.

Taxonomy

The red-shouldered hawk was formally described in 1788 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's ''Systema Naturae''. He placed it with the eagles, hawks and relatives in the genus '' Falco'' and coined the binomial name ''Falco lineatus''. Gmelin based his account on the "barred-breasted buzzard" of John Latham and the "red shouldered falcon" of Thomas Pennant. Latham had described a preserved specimen from North America in the Leverian collection while Pennant's specimen formed part of the collection of Anna Blackburne and had come from Long Island. The red-shouldered hawk is now placed with 27 other species in the genus ''Buteo'' that was introduced in 1799 by Bernard Germain de Lacépède. The genus name ''buteo'' is Latin for a "buzzard". The specific epithet ''lineatus'' is Latin meaning "marked with lines" or "lined".

Five subspecies are recognised:
* ''B. l. lineatus'' (Gmelin, 1788) – east North America
* ''B. l. alleni'' Ridgway, 1885 – central south Texas to North Carolina and north Florida (USA)
* ''B. l. extimus'' Bangs, 1920 – south Florida and the Florida Keys (USA)
* ''B. l. texanus'' Bishop, 1912 – south Texas (USA) to southeast Mexico
* ''B. l. elegans'' Cassin, 1855 – south Oregon (USA) to Baja California (Mexico)

Description

Males are long and weigh on average . Females are slightly larger at in length and a mean weight of . The wingspan can range from .Red-shouldered Hawk (''Buteo lineatus'')
Tpwd.state.tx.us. Retrieved on 2012-12-19. Adult birds can vary in mass from . Among standard measurements, the wing bone is long, the tail is long and the tarsus is . Adults have brownish heads, reddish chests, and pale bellies with reddish bars. Their tails, which are quite long by ''Buteo'' standards, are marked with narrow white bars. Red "shoulders" are visible when the birds are perched. These hawks' upper parts are dark with pale spots and they have long yellow legs. Western birds may appear more red, while Florida birds are generally paler. The wings of adults are more heavily barred on the upper side. Juvenile red-shouldered hawks are most likely to be confused with juvenile broad-winged hawks, but can be distinguished by their long tails, crescent-like wing markings, and a more flapping, ''Accipiter''-like flight style. In direct comparison, it is typically larger and longer proportioned than the broad-wing, though is slightly smaller and more slender than most other common North American ''Buteo'' species. This bird is sometimes also confused with the widespread red-tailed hawk. That species is larger and bulkier, with more even-sized, broad wings, and is paler underneath, with a reddish tail often apparent. The red-tail is also more likely to soar steadily, with wings in a slight dihedral.

Distribution and habitat

An eastern population ranges west through southern Canada from southern New Brunswick and Ontario to the eastern edge of the U.S. Great Plains, south to Florida, the Gulf Coast, and eastern Mexico. Only northernmost populations are migratory. A western population breeds west of the Sierra Nevada from northern California to northern Baja California, and has recently expanded into Oregon and Arizona, and east of the Sierra Nevada in California and southern Nevada.

Eastern populations winter from southern Wisconsin, Oklahoma, Ohio, and southern New England south to the Gulf Coast, occasionally throughout breeding range. In winter, they are reported south to Jalisco and Veracruz, Mexico. Western populations are largely nonmigratory. Throughout its winter range, this species avoids higher elevations.

Eastern birds occasionally wander west (e.g., Colorado, Kansas, West Texas, Manitoba, North Dakota) in migration; western birds have strayed east to Arizona, Nevada, Idaho, and Utah, and north to Washington.

In the east, individuals from the northern half of the species’ range are migratory. In the west, most populations are local. Red-shouldered hawks are short- to moderate-distance migrants, with most individuals traveling distances between 300 and 1,500 km each way. The species follows leading lines, migrating along inland ridges and coastlines. Larger numbers of red-shouldered hawks are counted at coastal watch sites than at inland sites. Juveniles often precede adults on migration in autumn, whereas adults precede juveniles in the spring. Red-shouldered hawks typically migrate alone, although they sometimes form small flocks of three or more birds. The species usually avoids crossing large bodies of water. While migrating, red-shouldered hawks are observed in soaring, gliding, and flapping flight.

A study of red-shouldered hawk home range and habitat use in southern California found average home range of and showed fair adaptability to human-altered landscapes, which is important as riparian forest habitat has diminished by 98% from 1850 to 1977 in California's Central Valley.

Red-shouldered hawks are forest raptors. In the east, they live in bottomland hardwood stands, flooded deciduous swamps, and upland mixed deciduous–conifer forests. They tend to live in stands with an open subcanopy, which makes hunting easier. They are not exclusively birds of deep forest, though; one can find red-shouldered hawks in some suburban areas where houses or other buildings are mixed into woodlands. In the west, they live in riparian and oak woodlands, and also in eucalyptus groves and some residential areas.

Behavior

Food and feeding

Red-shouldered hawks search for prey while perched on a treetop or soaring over woodlands. When they sight prey, they kill it by dropping directly onto it from the air. They may cache food near their nest for later consumption. When in clearings, they sometimes fly high and then drop to surprise prey. Red-shouldered hawks, like most raptors, have very good vision and reasonably good sense of hearing, with talons capable of killing animals as big as their own size. Small mammals are typically the most common prey, especially rodents. Voles, gophers,