The Red-shouldered Hawk inhabits a broad array of North American forests, but favors mature, mixed deciduous-coniferous woodlands, especially bottomland hardwood, riparian areas, and flooded deciduous swamps. In the West, this species prefers riparian and oak (Quercus spp.) woodlands, but is also found in eucalyptus groves and suburban areas with nearby woodlots.
This hawk generally hunts from a perch, waiting for its prey to reveal itself and then swooping down to snatch it from the ground or water surface. The Red-shoulder's diet is broad, although small mammals (especially chipmunks, mice, and voles), frogs, and snakes comprise the bulk of its diet in most areas. Birds, crayfish, and insects are key food items in certain areas and seasons.
Distinguished by its “red” shoulder patches, black-and-white checkered flight feathers (seen from above), and translucent, crescent-shaped wing panel in the outer primaries (seen from below when the wing is backlit), the Red-shouldered Hawk has been well surveyed at hawk watch locations throughout North America. It is a partial migrant, with only northernmost populations moving south for winter (Figure 1).
The Red-shouldered Hawk is a vocal bird early in the breeding season when courting and establishing its territory. It usually arrives on breeding territory in early spring, building its nest below the canopy but more than halfway up a tree in a crotch of the main trunk. Females provide most of the incubation for eggs and generally all of the brooding for young, while males supply the female and young with nearly all their food, until the young near fledging. Young leave the nest at about 6 weeks of age, but may continue to be fed by their parents for another 8–10 weeks, although little is known about immature Red-shouldered Hawks after they leave the nest.
Once considered common or abundant in the eastern part of its range, local populations of the Red-shouldered Hawk have apparently diminished in the northern U.S. during the last two centuries (probably owing to destruction of large, mature forests), but there are few data to document this decline. Currently most populations appear stable, although this needs study. Reversion of farmlands to forest offers some hope of habitat increases for this species, at least in the Northeast.
The Red-shouldered Hawk population encompasses considerable variability. Birds in some regions inhabit primarily extensive, mature forests remote from human activity ( Johnson 1989d , Bosakowski et al. 1992c , Bosakowski and Smith 1997 ). Others, particularly in the West ( Bloom and McCrary 1996 , Rottenborn 2000 ) but also in the East ( Dykstra et al. 2000 ), thrive in suburban habitats with nearby woodlands. Variability is also evident in prey selection: northern birds tend to eat primarily small mammals ( Portnoy and Dodge 1979 , Penak 1982 , Welch 1987 ) while southern birds focus on amphibians and snakes ( Howell and Chapman 1998 , Parker and Tannenbaum 1984 , Townsend 2006 ), but even within a single location, Red-shouldered Hawks demonstrate dietary flexibility, switching prey from year to year, depending on availability ( Bednarz and Dinsmore 1982 , Townsend 2006 ).