Family Hawks, Eagles (Accipitridae)

Least Concern

Northern Harrier (Circus hudsonius)


Taxonomy

French: Busard des marais German: Hudsonweihe Spanish: Aguilucho de Hudson
Taxonomy:

Falco hudsonius

Linnaeus

, 1766,

Hudson Bay

.

Closely related to C. cinereus, with which it has been treated as conspecific. Until recently was considered conspecific with C. cyaneus, but differs in having (first three characters in male) throat and upper breast greyish-white with mid-brown streaking vs pure blue-grey (ns[2]); lower breast to belly white with heavy mid-brown streaking turning to spotting on lower underparts and thighs vs pure white (3); upperside of outer primaries black and shading to grey basally vs all black (2); in female, underparts a shade darker (ns[1]); in juvenile, underparts rich dark rufous with sparse dark streaking vs pale brownish-buff with heavy dark streaking (3). Distinct from C. cinereus on account of (first two characters in male) throat and upper breast greyish-white with mid-brown streaking vs pure blue-grey (ns[2]); lower breast to belly white with heavy mid-brown streaking turning to spotting on lower underparts and thighs vs white with dense rufous barring (3); trailing edge of underwing dark grey vs mid-grey, weaker on primaries (2); in female, underparts heavily streaked, not barred (3). Monotypic.

Distribution:

North America S to Baja California (NW Mexico) and SE Virginia (USA); winters S to Panama and rarely N South America.

Descriptive notes

41–50 cm; male 290–390 g, female 390–600 g; wingspan 97–122 cm. Medium-sized harrier with long wings, tail, and legs and white rump in both sexes; as... read more

Voice

Similar to that of C. cyaneus. Males cackle during sky dance, and both sexes give... read more

Habitat

Variety of open habitats including marshlands, grasslands, meadows, deserts, sagebrush (... read more

Food and feeding

Summer diet consists mostly of small and medium-sized mammals (voles, mice, ground squirrels and juvenile lagomorphs) and birds (mostly... read more

Breeding

Egg laying occurs from late Mar to late Jun, with peak in mid-Apr to mid-May. More than 15% of males polygynous in high vole (Microtus... read more

Movements

Completely migratory in N part of breeding range and partially migratory in remainder of range,... read more

Status and conservation

Not globally threatened (Least Concern). CITES II. Population trends difficult to interpret because of nomadic movements in response to changes in prey availability.... read more

Recommended citation

del Hoyo, J., Collar, N. & Marks, J.S. (2018). Northern Harrier (Circus hudsonius). In: del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona. (retrieved from https://www.hbw.com/node/467351 on 11 December 2018).