Sharp-shinned Hawk (Accipiter striatus)

Distribution

Breeding: Most of Canada and Alaska below tree line, south through western United States to Central America; in East, to New England, and south in Appalachians to Georgia. Also in Cuba. A more northern distribution than the Cooper's Hawk, breeding mainly in boreal forests and in western mountains. However, may breed in low densities in forested areas throughout North America.

Winter: Highly migratory, with large numbers passing hawk watching sites each fall. May winter throughout central and southern United States and as far south as the Bahamas, the Lesser Antilles, and South America. At least some stay north to southern Canada, especially in the vicinity of bird feeders, where prey is abundant.

Breeding habitat

Coniferous and mixed forests. May nest in woodlots, conifer plantations, riparian forests, or forest patches in a matrix of farmlands. May prefer open stands of trees rather than dense continuous stands; this preference may vary by region. Often found near forest openings or edges, and near a stream, lake, or other body of water. Like the Cooper's Hawk, the sharp-shin may be nesting with increasing frequency near sources of human disturbance.

Conservation status

The Sharp-shinned Hawk is a characteristic species of northern and montane coniferous forests, and being a top predator, it is a species of conservation importance. This hawk is listed as a species of concern in several states and provinces. Although migration-count data have indicated a decline in populations, breeding survey data indicate an increase. Like most raptors, this species is poorly monitored, and its precise habitat requirements are poorly known. In particular, understanding its sensitivity to forest fragmentation and various land-use practices will be important for conserving future populations.

Description

Small-sized (pigeon or jay), forest-dwelling accipiter with a long, narrow tail and short rounded wings. Marked reverse sexual size dimorphism, with males weighing about 65% of females. Tail appears square tipped when folded, though this is less apparent when tail is spread. Central two tail feathers somewhat shorter than others, often causing tail to appear notched. Tail has alternating light and dark bands with a thin, white, terminal band. May soar during mornings, migration, and displays, but most flight is active, with periods of flapping alternating with short glides. Wingbeats are noticeably more rapid than those of the Cooper's Hawk and flight appears more buoyant. In flight, appears to be "short-necked," because head does not extend forward beyond the leading edge of the wings. Very thin legs noticeable when perched. Male: Dark gray-brown to slate-gray back, with a slightly darker gray crown that blends with nape. Finely barred rufous underparts. Undertail coverts pure white. Iris color varies from deep reddish-orange to ruby red. Legs and cere yellow. Female: Same coloration as male, but larger body size. Juvenile: Attains adult plumage in second year, hatch-year birds wear juvenal plumage through their first winter. Back and upper-wing coverts medium brown. Head dark brown with faint lighter superciliary line. Underparts creamy white with heavy reddish-brown streaking, undertail coverts white. Iris greenish-yellow to yellow, cere yellow, legs greenish-yellow.

Vocalizations

Song: None.

Calls: Does not call frequently, except during breeding season, and has a small repertoire of vocalizations. Most common call is the kik-kik-kik alarm call that may be given by either sex; also sometimes given by both members of a “duetting” pair during breeding season or during displays. Female has loud “wail” call. Juveniles may give a begging call or “hunger shriek,” which sounds like a thinner, higher pitched version of the adult wail call. This call may be given by several nestlings at once and may also be used by fledglings that are still dependent on parental feeding.

Foraging strategy

Most prey is taken while “still-hunting” from ambush or by stealthy approach flights that take advantage of landscape features to hide the approaching hawk. This may entail a twisting, circuitous flight at high speed and low altitude levels. Sharp-shinned Hawks are superb and powerful flyers, capable of rapid flight through dense vegetation. Prey is often taken in flight. Often hunt around bird feeders.

Diet

Most (90–97%) of the prey taken are birds, a higher proportion than either of the other North American accipiters. Avian prey may range in size from warblers and sparrows to American Robins. Smaller males take correspondingly smaller prey, with prey weights averaging around 60% of those taken by female.

Behavior and displays

• Both males and females may engage in “slow flight” territorial displays in which the birds fly with stiff, slow, exaggerated wing beats while exposing white undertail coverts. Both sexes may give the kik-kik-kik call during these flights.

• The kik-kik-kik alarm call or “undulating flight” display may be given in response to intruders in the vicinity of a nest.

Courtship

• Courtship behavior is not well understood.

• It is likely that the male obtains and defends a breeding territory and attracts a female by calling and performing display flights.

• Courtship flights may also occur, which can involve both birds soaring on thermals, or engaging in a “slow flight” or an “undulating flight.” During slow flight, one or both birds alternate periods of extremely slow, exaggerated wingbeats with short glides. It has been reported that during undulating flight birds follow a gradually descending path. This display may be given in response to an intruder in the vicinity of a nest.

Nesting

Nest Site: Nests built in mature trees against trunk, supported by one or more large branches and generally shaded from above. Males may show a high degree of territory fidelity, with several old nests located within a small area.

Height: 20–60 feet (6–18 meters).

Nest: Substantial platform of large, often fresh, twigs broken from branches. Center lined with bark chips. Males assist in building the nest. Old nests of Cooper’s Hawks, crows, and other species may be refurbished and reused.

Eggs: Around 4, with an interval of about 2 days between the laying of each egg. Earliest egg records from most states are around middle of April.

Incubation period: Incubation by female (the male does not normally incubate) often begins with the third egg and may last about 30 days. All eggs tend to hatch within a 2–3 day period.

Nestling period: Young remain in nest about one month, guarded and brooded by female and fed by male who does most of the hunting. During latter phase of the nestling period, female may hunt more often, leaving young alone in nest. Young normally eject feces over the side of the nest, and the ground and bushes below nest may be liberally splattered with whitewash before young fledge.

Fledgling period: Fledglings remain in vicinity of nests and continue to be fed by parents until they are about 8 weeks old.

Broods: Normally only one brood per year, but may make another breeding attempt if a nest fails early in the season.

Notes

• A plucking post, which may be a fence post, stump, or fallen tree, is usually located within about 150–200 feet (45–61 meters) of the nest. May be recognized by an accumulation of feathers from plucked prey and by whitewash splattered in the surrounding area. This is often the best clue that an active nest is nearby.