Northern Harrier

Circus cyaneus

Taxonomy:
Class: Aves
Order: Falconiformes
Family: Accipitridae
Subfamily: Circinae
Genus: Circus

Length: 16-18 in. (male); 18-20 in. (female)
Weight: 10-14 oz. (male); 14-21 oz. (female)
Wingspan: 38-43 in. (male); 43-48 in. (female)

Common Names: blue hawk (male), cinereous harrier, Frog Hawk, hen harrier, marsh hawk

Etymology: kirko (Greek) - "circle," from the bird's habit of flying in circles; kyaneous - (Greek) - "dark blue," male's back color

Description: The northern harrier has an owl-like facial disk, long wings and tail, and a white rump patch. Its dark head appears hooded. Wing tips do not reach tip of tail. Sexes have different color plumages: males are gray with black wing tips, females are brown with a streaked breast. Immature harriers look like females, with a rusty breast. Adult male harriers have bright lemon yellow eyes; adult female's eyes are amber to pale yellow (by 5th year). Immature male has grayish brown eyes; immature female's eyes are chocolate brown.

Flight: Harriers often use slow quartering flight, in a strong dihedral. Courtship flights include steep climbs, dives, and series of loops with bird upside down at top of loop. They can hover since they have low wing loading (large wing surface vs. body weight).

Voice: Distress call is a Kek or Ke, high pitched and uttered in rapid succession. Food call by females is a piercing, descending scream - eeyah eeyah - that may be repeated for minutes in presence of mate in an apparent effort to induce food transfers.

Habitat: Medium to tall prairie grass, wetlands, marshes, logged or burned wood lots, tundra. Northern harriers will usually perch on the ground, but will use fence posts, or other low perches. In winter, they use communal ground roosts, sometimes found with short-eared owls.

Distribution: The northern harrier is the sole North American species from a worldwide cosmopolitan genus of 10 species. They are fairly common throughout North America. Northern populations are migratory, spending winters in southern United States.

Nesting: Northern harriers are ground nesters, and build within patches of dense, often tall, vegetation in undisturbed areas. They are polygamous - one male will mate with up to five females, depending on prey availability. Mean clutch size is 4.4, and incubation lasts 30-32 days. Chicks will wander after 15-20 days, possibly to avoid predation. They breed at the age of two, sometimes three, years.

Food: Rodents, birds, reptiles, and frogs. Males take more birds, females take more mammals. Northern harriers have reportedly drowned waterfowl.