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GALLERIES > BIRDS > FALCONIFORMES > ACCIPITRIDAE > SHARP-SHINNED HAWK [Accipiter striatus]


Sharp-shinned Hawk Image @ Kiwifoto.com
 
 
Location: Tucson, AZ
GPS: 32.3N, -110.9W, elev=2,487' MAP
Date: March 15, 2009
ID : 7C2V6011 [3888 x 2592]

Sharp-shinned Hawk Image @ Kiwifoto.com
 
 
Location: Tucson, AZ
GPS: 32.3N, -110.9W, elev=2,487' MAP
Date: March 15, 2009
ID : 7C2V6001 [3888 x 2592]

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Sharp-shinned Hawk Image @ Kiwifoto.com
 
 
Location: Santa Fe, NM
GPS: 35.7N, -105.9W, elev=8,111' MAP
Date: November 25, 2012
ID : B13K0646 [4896 x 3264]

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SPECIES INFO

The Sharp-shinned Hawk (Accipiter striatus) is a small hawk. In fact "Sharpies" (as they are abbreviated by North American birdwatchers), are the smallest to reside in USA and Canada, though some Neotropical species are smaller (notably the aptly named Tiny Hawk). The taxonomy is far from resolved, with some authorities considering the southern taxa three separate species: White-breasted Hawk (A. chionogaster), Plain-breasted Hawk (A. ventralis) and Rufous-thighed Hawk (A. erythronemius). See taxonomy for further on this.

This species is widespread in North America, Central America, South America and the Greater Antilles. Below the distributions of the four groups (see taxonomy) are described as they roughly occur from north to south:

The nominate (A. s. striatus) group is widespread in North America, occurring throughout a large part of USA and Canada, except in the ice-covered regions of the far north. Populations in the northern part of the range migrate south and spend the non-breeding season (winter) in southern USA, Mexico and Central America as far south as Panama, with a smaller number spending the winter in the Greater Antilles. Resident populations exists in temperate parts of USA, Canada (in a few coastal regions), Mexico (highlands from Sonora to Oaxaca), Cuba, Hispaniola and Puerto Rico.

A. (s.) chionogaster (White-breasted Hawk) occurs in highlands from far southern Mexico (Chiapas and Oaxaca), through Honduras, Guatemala and El Salvador, to Nicaragua. It is, as far as known, resident, but some local movements may occur.

A. (s.) ventralis (Plain-breasted Hawk) occurs in the coastal mountains of northern Venezuela and Colombia, south through the Andes from western Venezuela, through Colombia, Ecuador and Peru, to central Bolivia. A disjunct population occurs in the Tepuis of southern Venezuela (likely to extend into adjacent parts of Roraima in far northern Brazil, but this remain unconfirmed). It is, as far as known, resident, but some local movements may occur.

A. (s.) erythronemius (Rufous-thighed Hawk) is widespread in eastern South America in eastern and southern Brazil, Uruguay, Paraguay, north-eastern Argentina and south-eastern Bolivia. It is, as far as known, resident in some regions and migratory in others. The movements are generally poorly understood, but it only occurs seasonally at some localities in Argentina.

It is commonly separated into four species. If split, the northern group (see distribution) retains both the scientific and the common name: Sharp-shinned Hawk (A. striatus). In addition to the nominate taxon (A. s. striatus), it includes subspecies perobscurus, velox, suttoni, madrensis, fringilloides and venator. The three remaining taxa, each considered a monotypic species if split, are the White-breasted Hawk (A. chionogaster; Kaup, 1852), Plain-breasted Hawk (A. ventralis; Sclater, 1866) and Rufous-thighed Hawk (A. erythronemius; Kaup, 1850). The breeding ranges of the groups are entirely allopatric, although the wintering range of the nominate group partially overlaps with the range of chionogaster (as is also the case with certain taxa within the nominate group). This combined with differences in plumage (see appearance) and, apparently, certain measurements, has been the background for the split, but hard scientific data is presently lacking (AOU). Disregarding field guides, most material published in recent years (e.g. AOU, Ferguson-Lees et al p. 586, and Dickinson et al) has therefore considered all to be members of a single widespread species but not without equivocation: Ferguson-Lees et al. say that if they were to make a world list, they would include the three taxa as separate species (p. 75), and the AOU's comment includes the note "split almost certainly good".

Storer (1952) suggested that the southernmost populations within the nominate group were paler below, thus approaching chionogaster. This has also been reflected in recent guides, where A. s. madrensis of southern Mexico is described as being relatively pale below (compared to more northern subspecies), but if this is a sign of intergradation with chionogaster or a north-south cline which includes both the members of the nominate group and chionogaster remains unclear. In Bolivia, ventralis and erythronemius approach each other, but no evidence of intergradation is known something that, without actual specimens, also would be hard to prove due to the variability in the plumage of ventralis.

It occurs in a wide range of woodland and forest types, both dominated by conifers and by various types of broad-leaved trees (especially oaks). The largest populations of the nominate group (see taxonomy) are thought to occur in the temperate boreal forests, but winter in warmer regions further south (see distribution). The taxa suttoni, madrensis (both from the nominate group), chionogaster (White-breasted Hawk) and ventralis (Plain-breasted Hawk), are found in upper tropical to temperate highlands; mainly at altitudes of 300-3000 m (990-9850 ft), but occasionally down to near sea-level and up to 4000 m (13100 ft). The taxon erythronemius (Rufous-thighed Hawk) is found in tropical and subtropical regions; both in lowlands and highlands.

A small Accipiter hawk. Males are 24 to 30 cm (9.5 to 12 in) long, have a wingspan of 52 to 58 cm (20 to 23 in) and weigh from 87 to 114 g (3.1 to 4 oz). As common in Accipier hawks, females average distinctly larger at a length of 29 to 37 cm (11.5 to 14.5 in), a wingspan of 58 to 68 cm (23 to 27 in) and a weight of 150 to 218 g (5.3 to 7.7 oz). Measurements given here are for the northern group, but they are comparable for the remaining. Adults have short broad wings and a long square-ended tail banded in blackish and grey (often narrowly tipped white). The remiges (typically only visible in flight) are whitish barred blackish. Legs yellowish. The hooked bill is black and the cere is yellowish. The remaining plumage varies depending on group:

These birds surprise and capture all their prey from cover or while flying quickly through dense vegetation. They are adept at navigating dense thickets. The great majority of this hawk's prey is small birds, especially various songbirds such as sparrows, wood-warblers and American Robins. Birds caught have ranges in size from a 4.4 g-Anna's Hummingbird to a 577 g (1.2 lb)-Ruffed Grouse and any bird within this size range is potential prey. Typically, males will target smaller birds, such as sparrows, and females, will pursue larger prey, like American Robins and flickers. They often pluck the feathers off their prey on a post or other perch. Rarely, Sharp-shinned Hawks will also eat rodents, lizards, frogs, snakes, and large insects.

Sharp-shinned Hawks will construct a stick nest in a large conifer or dense group of deciduous trees. Clutches of 3 to 8 eggs have been recorded, but are usually 4 to 5 eggs. The eggs measure 37.6 x 30 mm (1.48 x 1.18 in) and weigh about 19 g. The eggs are prized by egg-collectors, because they are heavily marked with surprisingly colorful and varied markings. The incubation period is thought to average at about 30 days. After hatching, the young are brooded for 16 to 23 days by the female, while the male defends the territory and catches food. The young fledge at about a month old and rely on their parents for feeding and protection another 4 weeks. The nesting sites and breeding behavior of Sharp-shinned Hawks are generally secretive, in order to avoid the predation of larger raptors, such as the Goshawk and the Cooper's Hawk. While in migration, adults are sometimes preyed on by most of the bird-hunting, larger raptors, especially the Peregrine Falcon. The breeding behavior of the taxa chionogaster (White-breasted Hawk), ventralis (Plain-breasted Hawk) and erythronemius (Rufous-thighed Hawk) are comparably poorly known, but based on the available knowledge they appear to differ little from that of the nominate group.



                                     




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