• Total length: 45 to 61 cm.
• Wing chord length: 327 to 405 mm.
• Tail: 228 to 266 mm.
• Weight: 350 to 530 grams
• Northern Harrier are sexually dimorphic.
• Upper parts of males are light grey to dark grey, females are brown above.
• Upper tail coverts of the Northern Harrier are white in both sexes. This is commonly referred to as a white ‘rump patch’. When perched, the wing tips cover the rump patch. Remainder of tail is grey with narrow bands. Underside of wings is mostly white, while under parts of the body are white with flecks of light brown.
• The head has a partial facial disk, similar to the facial disk of an owl.
• Wings, tail and legs are long and slender.

• Circus cyaneus breeds from northern Alaska, northern Yukon, northern Northwest Territories, southern Nunavut, northern Saskatchewan, Manitoba and Ontario, central Quebec, and Newfoundland, south to southern California, northern Arizona, northern New Mexico, northern Texas, central Oklahoma, southern Missouri, southern Illinois, Ohio, Pennsylvania and northern Virginia.
• The Northern Harrier winters from Alaska, southern British Columbia, Alberta and Saskatchewan, Nebraska, Wisconsin, southern Michigan, southern Ontario, New York and Massachusetts south throughout the United States and Central America.
• In Alberta, the Northern Harrier is found in all Natural Regions.

• Home range size is variable depending on habitat characteristics; estimations of home range size range from 1 to 16 square kilometres.
• The Northern Harrier prefers open grassland habitats, and associated wetlands.
• Circus cyaneus commonly use riparian habitats and cultivated areas. They use brackish wetlands in addition to fresh water wetlands - this helps to decrease competition with other hawks.

• The Northern Harrier is a partial migrant, but migrants often travel great distances (i.e. >1500 km).
• Southward migration occurs between mid August and November, with peak times likely occurring from late September through October.
• The northward migration occurs from February to early May.

• The Northern Harrier is able to adapt its diet according to time of year and habitat.
• Circus cyaneus specialize for feeding on small to medium sized mammals, especially rodents such as voles.
• Many populations have been reported to switch from rodents to small passerine birds during the breeding season.
• Rodents, young passerines and lagomorphs are generally the principle prey.
• Northern Harrier may also kill larger birds, such as adult waterfowl.
• Exhibits similar hunting techniques to the Short-eared Owl; the Northern Harrier is the only hawk able to locate prey using only acoustic clues.
• Hunts by flying at low speeds just above low growing vegetation, with its wings tilted upward to allow for maximum aerodynamics.
• Uses the element of surprise attack, flying in zigzag patterns.
• Hunts in open habitats, with males displaying a preference for more open habitats than females.
• Females will displace males from preferred hunting habitat.

• The Northern Harrier may be either monogamous or polygamous. Males may have up to four mates in some areas.
• Pair formation likely occurs on the breeding grounds.
• Nests are on the ground, in tall grasses or low shrubs, avoiding areas with sparse vegetation.
• The nest site must provide visual protection throughout the breeding season.
• Nest site may be selected by either the male or the female. It is often initiated by the male building a nesting platform.
• Material for the nest is collected by both the male and female, but only the female adds to the nest after the initial platform is built.
• Nests are constructed of grasses, reeds, forbs and other plant material.
• Eggs are laid from mid April to early May. The egg laying interval is generally 2 days, occasionally 3 days.
• Only one brood produced per season, but a replacement clutch may be laid if the initial clutch is lost during early incubation.
• The clutch typically consists of 4-5 eggs, but may occasionally be up to 7 eggs.
• Incubation is 29 to 31 days for each egg and 29 to 39 days for the clutch.
• Incubation is done by the female. Some reports suggest that males may participate in incubation and brooding, but this has not been confirmed.
• Hatching of the altricial young is asynchronous.
• Female broods young from hatching for up to 14 days.
• Male provides all of the food for the female and nestlings throughout incubation until the end of brooding.
• Fledging occurs at approximately 30 to 35 days.

Conservation Status:

• Federal: Not at Risk
• Provincial: Sensitive