That small raptor bursting out of a hidden perch and rocketing through your yard in pursuit of small birds is a Sharp-shinned Hawk. It shares the genus Accipiter with the Cooper’s Hawk, a similar looking but slightly larger hunter. They are both uncommon residents of Edmonds and most of North America and they both hunt smaller birds. They cause much identification grief for birders because the two species can be difficult to distinguish.
In overhead flight, the Sharp-shinned Hawk is relatively easy to identify because the tip of its tail is like a straight edge (see fourth photo). The tail of a Cooper’s Hawk is longer and rounded at the tip. The adult Sharp-shinned Hawk has a dark gray head and nape, the gray usually ending just below the eye. The adult Cooper’s Hawk has a gray head but the gray does not extend below the eye and it is not on the nape of the neck. Its dark gray crown is referred to as the Cooper’s cap. It shows well in the last photo, which is a small male Cooper’s that I have included for comparison. Also notice that the legs of a Sharp-shinned Hawk are much thinner than those of a Cooper’s Hawk.
While Edmonds is in a year-round range for the Sharp-shinned Hawk, it is the most migratory of the three Accipiters, breeding north to the tree line in Canada and Alaska and wintering as far south as Panama. This hawk tends to avoid open country, preferring mixed or coniferous forests, deciduous woodlands, thickets, and edges. It mostly stays out of sight so that it can more successfully ambush song birds.
Small birds, about the size of a sparrow up to the size of a robin, comprise the bulk of a Sharp-shinned Hawk’s diet. It also consumes small numbers of rodents, bats, squirrels, snakes, frogs, lizards, and large insects. It hunts mostly by perching inside foliage and waiting for a small bird to approach or by approaching its prey through dense cover. With swift flight it then captures its prey in its talons. It will also hunt by flying rapidly through trees or low over the ground, threading its way among any obstacles and catching its prey by surprise.
In courtship, a pair of Sharp-shinned Hawks may circle above the forest, calling. They both may spread their fluffy white undertail covert feathers in some courtship displays. The male may also fly high and dive steeply into the woods.The nest site is well concealed, high in a dense conifer in a forest or thick grove of trees. While both sexes bring nest materials, the female mostly builds the platform structure out of sticks and then lines it with twigs, grass, and strips of bark. Sometimes the nest is built on top of an old squirrel or crow nest.
The female incubates her four to five eggs for about a month. During this period the male brings her food and may sit on the eggs while she eats. Once the chicks hatch, the male continues to bring food, which the female feeds to the nestlings. After three to four weeks, the young will move out of the nest to nearby branches. They can fly at five to six weeks of age.
The Sharp-shinned Hawk is quiet, elusive, and nests in solitary pairs. It seeks dense cover for its nest to avoid becoming prey to the Northern Goshawk, the third North American Accipiter that mostly lives and hunts in mountain forests. Records are scarce on life expectancy but one banded Sharp-shinned Hawk lived to be 12 years of age. A group of any hawks has inspired a number of collective nouns, including boil, knot, spiraling, stream, and tower.
If you have bird feeders, it can be disturbing to see small song birds taken as prey by either the Sharp-shinned or Cooper’s Hawk. It is, however, an opportunity to understand the role of these hawks in the food chain. They do little harm to small bird populations because they occur in lower numbers, produce fewer young, and breed less often than the smaller birds that they hunt. Most of their hunting occurs in places other than backyard feeding stations. If one continues to hunt in your yard, you can take the feeders down for a couple of weeks. The hawk will move on to more favorable hunting areas and the song birds will return once you re-hang the feeders.
The conservation status of the Sharp-shinned Hawk is that of low concern. Monitoring between 1966 and 2015 revealed a stable population. While there is little data on nesting success because this hawk is so solitary and elusive, population estimates have been made from yearly migration counts. The global population is approximately 700,000 birds, with 49 percent spending some part of the year in the U.S., 40 percent in Canada, and 14 percent in Mexico. As did other birds of prey, the Sharp-shinned Hawk suffered breeding failure when DDT was in use in North America. Some still have high levels of DDT in their bodies because some of the song birds they eat spend part of the year in South America where DDT is still in use. In this way the pesticide continues to spread up through the food chain. The Sharp-shinned Hawk is also vulnerable to habitat loss. Since it requires dense stands of trees for breeding, its future relies on preservation of wooded wilderness.
You can listen to a female flight call and a male song here: https://www.xeno-canto.org/354364.
— By Carol Riddell
Carol Riddell manages the bird education displays, on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.