Sharp-shinned hawks are the smallest accipiters (bird hawks) in North America. Males are 24 to 27 cm long and weigh 87 to 114 g. Females are larger, measuring 29 to 34 cm in length and weighing 150 to 218 g. Males have a wingspan of 53 to 56 cm and females 58 to 65 cm.
Sharp-shinned hawks have bluish-gray to slate colored upperparts, with darker coloration on the crown. Their underparts are white with brown bars and their short, rounded wings are dark above and light below. Females have fewer bars on the breast, and their upper parts are more brownish. Sharp-shinned hawks have a short, dark colored, hooked beak and yellow legs and feet. Their tail is square-tipped when not spread and has three to five dark stripes with a small white stripe on the tip. Molting does not change the adult’s appearance. Juveniles have more streaking and/or barring and paler coloration than adults. Sharp-shinned hawks look similar to Cooper’s hawks (Accipiter cooperii) but are smaller. (Bildstein and Meyer, 2000; Gough, et al., 1998; Snyder and Snyder, 1991; Wheeler and Clark, 1995)
Sharp-shinned hawks can be found throughout much of North America, including Mexico. In South America, they are found from Venezuela to northern Argentina. Most of the North American populations migrate to the southern parts of their range in winter. (Bildstein and Meyer, 2000; Sullivan, 1994)
Sharp-shinned hawks are forest birds. They are found in pine, fir and aspen forests (among others). They can be found hunting in forest interior and edges from sea level to near alpine areas. Sharp-shinned hawks can also be found near rural, suburban and agricultural areas, where they often hunt at bird feeders. (Bildstein and Meyer, 2000; Campbell, et al., 1990; Snyder and Snyder, 1991; Sullivan, 1994)
Little is known about the mating behavior of sharp-shinned hawks. They are known to perform mating displays and are thought to have only one mate at a time. (Bildstein and Meyer, 2000)
Sharp-shinned hawks breed during the season when there is a lot of food available. This is usually between late March and June. Sharp-shinned hawks begin building their nests soon after they arrive at the breeding ground. Nests are built in trees, usually 2.4 to 19 m above ground. The nests are made of twigs and are often lined with bark chips. The male and female both gather nesting material but the female does most of the building. Nest sites are re-used from year to year and new nests are built on top of old ones. The birds are territorial during breeding season and defend their nest site against intruders.
Sharp-shinned hawks normally breed only once a year and lay 4 to 5 eggs. Females usually lay one egg every-other day. Eggs are white or bluish with dark spots. They are about 37 by 30 mm and weigh about 9 g. Incubation lasts 21 to 35 days. Females do most of the incubating, but males will bring food to females while they are on the nest.
All of the eggs hatch within one or two days of each other. After hatching, the female broods the chicks for 16 to 23 days. This means that she uses her body to cover the chicks the same way that she covered the eggs to keep them warm and protected. The nestlings fledge (leave the nest) after 21 to 32 days. Male nestlings usually fledge sooner than females. The parents continue to feed the chicks for about 3.5 weeks after they fledge. Most sharp-shinned hawks breed for the first time when they are two years old. (Bildstein and Meyer, 2000; Campbell, et al., 1990; Snyder and Snyder, 1991)
Female sharp-shinned hawks do most of the incubating, but males bring food to females while they are on the nest. After hatching, the chicks are brooded (the female sits over the chicks to keep them warm and protect them in the same way she sits over the eggs) for 16 to 23 days. While the chicks are in the nest the male brings food to the female who tears it apart and feeds it to the chicks. Females also defend the nest against predators. The nestlings fledge (leave the nest) after 21 to 32 days. They continue to be cared for by the parents for about 3.5 weeks after fledging. (Bildstein and Meyer, 2000; Campbell, et al., 1990; Snyder and Snyder, 1991)
The oldest known sharp-shinned hawk lived to be 13 years old. However, most do not live longer than 3 years. Sharp-shinned hawks are killed by predators, hunters, and collisions with cars and buildings. (Bildstein and Meyer, 2000; Sullivan, 1994)
Sharp-shinned hawks are territorial when they are breeding. They keep intruders away by calling, chasing and attacking them. They are usually found alone, but sometimes form small groups when they migrate. Most North American populations are migratory; some fly distances of more than 1500 km. They leave their breeding grounds in August and return in March.
Sharp-shinned hawks are active during the day. Except while migrating, they usually fly below the canopy. They use their tail to steer while flying. (Bildstein and Meyer, 2000; Campbell, et al., 1990; Snyder and Snyder, 1991)
Their home range is usually between 0.9 and 2.8 square km. (Bildstein and Meyer, 2000)
Sharp-shinned hawks are usually quite silent. They call more often during the breeding season. Their alarm calls sound like “kek-kek-kek” or “kik-kik-kik.” Males make a “kip…kip” or “kew kew kew” call when they come to the nest, and females reply with a “keeeep.” Females and nestlings also make “eee” calls. (Bildstein and Meyer, 2000; Snyder and Snyder, 1991)
Sharp-shinned hawks mainly eat small birds. They also eat small mammals and large insects. They often catch birds at bird feeders and take young birds from nests. When they catch birds, sharp-shinned hawks pluck the feathers before eating the bird.
Sharp-shinned hawks often hunt from a perch and dart out from hiding to catch prey. Their long, sharp talons help them to grab onto prey and their short bursts of high-speed flight help them to catch their prey. They get all their water from prey and do not need to drink. (Bildstein and Meyer, 2000; Sullivan, 1994)
Their secretive behavior and camouflaged nests help sharp-shinned hawks avoid predators. Known predators of sharp-shinned hawks include: bald eagles (Haliacetus leucocephalus), peregrine falcons (Falco peregrinus) and northern goshawks (Accipiter gentiles). (Bildstein and Meyer, 2000; Sullivan, 1994)
Sharp-shinned hawks are important members of their ecosystem. They have an influence on small bird populations and are also an important food source for their predators.
Sharp-shinned hawks prey on songbirds, game birds and domestic fowl. (Sullivan, 1994)
Sharp-shinned hawk populations declined between the 1940’s and the 1970’s. The pesticide DDT that was commonly used at that time was harmful to the birds. The pesticide caused egg shells to be too thin and the eggs broke when the parents incubated them. Today there are other threats to sharp-shinned hawks. The birds that they rely on for food are becoming less common, there are harmful chemicals in the environment and the forest habitat of sharp-shinned hawks is being destroyed. (Bildstein and Meyer, 2000; Sullivan, 1994)
Alaine Camfield (author), Animal Diversity Web.
Kari Kirschbaum (editor), Animal Diversity Web.
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Campbell, R., N. Dawe, I. McTaggart-Cowan, J. Cooper, G. Kaiser, M. McNall. 1990. The Birds of British Columbia, Volume II: Non-passerines, Diurnal Birds of Prey through Woodpeckers. Victoria: The Royal British Columbia Museum.
Gough, G., J. Sauer, M. Iliff. 1998. "Sharp-shinned hawk (Accipiter striatus)" (On-line). Patuxent Bird Identification Infocenter. Accessed February 25, 2004 at http://www.mbr-pwrc.usgs.gov/id/framlst/i3320id.html.
Snyder, N., H. Snyder. 1991. Birds of Prey: Natural History and Conservation of North American Raptors. Stillwater, MN: Voyageur Press.
Sullivan, J. 1994. "Accipiter striatus" (On-line). Fire Effects Information System. Accessed February 25, 2004 at http://www.fs.fed.us/database/feis/wildlife/bird/acst/.
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