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Northern Harrier Fact Sheet

Northern Harrier
Circus cyaneus

New York Status: Threatened
Federal Status: Not Listed

Description

Photo of a male Northern Harrier hovering
Male Northern Harrier - © Gordon Ellmers

The Northern Harrier, formerly known as the marsh hawk, hunts primarily on the wing and may cover up to 100 miles per day. Its prey, consisting of mostly rodents and small birds, is detected using extremely keen hearing. This 16-24 inch (41- 61 cm), slender-bodied hawk has a long tail and wings, long yellow legs, distinct facial disks and a conspicuous white rump patch. In flight, the wings are held in a shallow "V." The adult male is pale gray on the head, back and wings. The gray tail is banded with six to eight gray-brown bars. There is cinnamon-brown spotting on the legs and flanks, and the wing linings and undertail are white. The eyes of an adult male are yellow. Female plumage is browner overall with dark streaks on the breast. The female is born with brown eyes which turn yellow at about three years of age. Juveniles resemble adult females, but have gray eyes. When startled, this species makes a rapid, nasal chattering "ke-ke-ke-ke-ke".

Life History

Photo of a Northern Harrier nest with young
Northern Harrier nest with young - © Hope Batcheller

This raptor is considered one of the most agile and acrobatic in North America. During the breeding season, the male performs an elaborate courtship flight consisting of a series of U-shaped maneuvers. The nest is a flimsy structure built of sticks and grass on the ground. It can be found in dense vegetation or situated in a slightly elevated position. The clutch averages five eggs. Incubation lasts 30-32 days and begins before the last egg is laid, so the young vary in size. The young fledge in 30- 41 days, then remain near the nest, dependent on their parents for three to four weeks. Clutches are larger and reproductive success is higher during years when vole populations are high.

Distribution and Habitat

Map of Northern Harrier Range
Northern Harrier Range

Northern Harriers breed in North America from northern Alaska and Canada south to central and southern California, Mexico and portions of the southern U. S., excluding the southeast region. Wintering occurs from southern Canada to northern South America. Communal flocks roost on the ground during winter and migratory periods in agricultural fields, abandoned fields and salt marshes. Breeding occurs in both freshwater and brackish marshes, tundra, fallow grasslands, meadows and cultivated fields.

Status

Map of Northern Harrier Distribution in New York
Distribution of Northrn Harrier in New York from
1st and 2nd NYS Breeding Bird Atlas Records

Historically, populations of Northern Harriers were considered abundant and widespread. However, significant declines began in the 1950's and were attributed to factors such as loss of breeding habitat and effects of pesticides. Reforestation, filling in of wetlands, changes in land use, changes in agricultural practices and urban and industrial development all contributed to habitat losses.

The number of blocks in which this species was detected changed little from the first to second New York State Breeding Bird Atlases (a decrease of 1%) but some shifts in the species range appear to have occurred in the state. Although New York State breeding populations appear relatively stable, Breeding Bird Survey trend data shows a survey-wide decline for this species at 1.7% per year.

Management and Research Needs

Photo of a female Northern Harrier
Female Northern Harrier
NYSDEC - Glenn Hewitt

Protection of suitable habitat is the most vital need of Northern Harriers. They require vast expanses of relatively intact open habitat. Population size and reproductive success of this species are largely dependent upon prey populations. It has been well documented that Northern Harrier populations and populations of their prey follow similar patterns of fluctuation. It is important that any management allow for healthy prey populations and provide habitats that are suitable for them as well.

Research and monitoring by the DEC is currently underway for this and other grassland raptor species with the goal of creating a greater understanding of the conservation needs of these declining birds. Recent efforts have been made to more closely monitor and identify wintering raptor concentration areas throughout New York State with the Northern Harrier included as a primary target species. This research has led to a better understanding of the importance of these concentration areas to the species, their response to changes in habitat and environmental conditions, and has led to the conclusive documentation of winter site fidelity for at least one location in New York State.

Additional References

Ehrlich, P.R., D.S. Dobkin and D. Wheye. 1988. The Birder's Handbook. Simon and Schuster, Inc., New York.

Farrand, Jr., J., Ed. 1983. The Audubon Society Master Guide to Birding. Vol. 1: Loons to Sandpipers. Alfred A. Knopf, Inc., New York. Pp.224-226.

Levine, E., Ed. 1998. Bull's Birds of New York State. Cornell University Press, Ithaca, NY. pp. 185-186.

Post, T.J. 2008. Northern Harrier. Circus cyaneus. Pp. 109-191 in McGowan, K.J. and K. Corwin, Eds. The Second Atlas of Breeding Birds in New York State. Cornell Univ. Press, Ithaca, NY.

Smith, G.A. 1988. Northern Harrier, Circus cyaneus. Pp. 102-103 in R.F. Andrle and J.R. Carroll, Eds. The Atlas of Breeding Birds in New York State. Cornell University Press, Ithaca, NY.

Smith, K.G., S.R. Wittenberg, R.B. Macwhirter and K. L. Bildstein. 2011. Northern Harrier (Circus cyaneus), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/210


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