Photo Credit: Bill Horn
SCIENTIFIC NAME: Circus cyaneus (Linnaeus)
OTHER NAMES: Blue Hawk (male), Frog Hawk, Hen Harrier, Marsh Harrier, Marsh Hawk, Mouse Hawk, White-rumped Hawk (Terres 1980).
DESCRIPTION: A medium-sized (43-58 cm [17-23 in.]; Nat. Geog. Soc. 1987), slim, long-tailed, long-legged hawk with a characteristic facial ruff that gives it an owl-like appearance. Sexes dichromatic, but both have conspicuous white rump patches. Adult male pale gray above and white below with reddish spots on underparts; wingtips edged in black. Adult female 12.5 percent larger and 50 percent heavier than male; predominantly dark brown above, light buffy below, with some streaking on underparts. Immatures resemble females; brown above, but reddish below (MacWhirter and Bildstein 1996). During courtship, both sexes emit a rapid series of kek or quik notes. Distress call similar, but given at higher pitch. Two subspecies recognized: larger northern harrier (Circus cyaneus hudsonius) and Eurasian hen harrier (C. c. cyaneus ) (MacWhirter and Bildstein 1996).
DISTRIBUTION: Breeding distribution large, but often highly discontinuous. In North America, occurs from northern
HABITAT: Breeds in open wetlands, including marshy meadows; wet, lightly grazed pastures; old fields; freshwater and brackish marshes; also dry uplands, including upland prairies, mesic grasslands, drained marshlands, croplands, cold desert shrub-steppe, and riparian woodlands. In both wetland and upland areas, densest populations typically associated with large tracts of undisturbed habitats dominated by thick ground vegetation. Wintering birds use a variety of open habitats dominated by herbaceous cover, including deserts, coastal sand dunes, dry plains, upland and lowland grasslands, salt- and freshwater marshes, croplands, pasturelands, abandoned fields, and open-habitat floodplains. Select habitats on the basis of availability and abundance of prey (MacWhirter and Bildstein 1996).
LIFE HISTORY AND ECOLOGY: Return to breeding grounds in March or April. Males establish territories and a monogamous pair bond often formed; however, simultaneous polygyny also reported. Nest is a platform of dry sticks, straws, weed stems, and grasses built primarily by female on ground, commonly near low shrubs, in tall weeds or reeds, sometimes in bogs (Terres 1980). A clutch of three to nine (usually five) white eggs laid in March-June. Females incubate eggs for 30-32 days, with young flying about 30-41 days after hatching (Serrentino et al. 1998). Male provides food to female during incubation and until young are 10-14 days old. Young become independent around 6.5-9.5 weeks after hatching (MacWhirter and Bildstein 1996). When hunting, usually flies low (3-10 m [10-33 ft.]) over ground, with a few wingbeats followed by a short glide with wings held up in a shallow V. Depends heavily on auditory and visual cues to locate prey such as small rodents, shrews, small birds, and insects. Roosts on ground, very often communally, outside the nesting season (MacWhirter and Bildstein 1996).
BASIS FOR STATUS CLASSIFICATION: Christmas Bird Count and Breeding Bird Survey data indicate population declines in
Author: Paul D. Kittle