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Northern Harrier - BirdForum Opus

Revision as of 07:28, 8 May 2020 by Jmorlan (talk | contribs) (Added image of adult female.)
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Male
Photo © by blubird
Las Gallinas, San Rafael, California, 18 December 2008

Alternative name: Marsh Hawk

Circus hudsonius

Identification

Juvenile
Photo © by Kadawe
Newbury Massachusetts, 6 October 2017

A medium-sized raptor, 43-58 cm (17¾-21¾ in) long and 97-122 cm wingspan; males smaller (350 g), females larger (530 g)
Male

  • Grey head and upper parts
  • Six outer primaries black
  • White rump
  • Back and wing (except for outer primaries) grey, mottled darker
  • Underparts pale grayish-white, with scattered orange-brown streaks on breast and flanks

Female

  • Quite a bit larger than the male
  • Brown upperparts
  • Brownish-white underparts, streaked and mottled darker
  • Very noticeable white rump

Juvenile

  • Similar to adult female but less streaked below and distinctly orange-toned

In flight

  • Shows five obvious 'fingered' (emarginated) primaries unless in moult.

Similar species

Adult male
Photo © by Stanley Jones
Anahuac National Wildlife Refuge, Chambers County, Texas, USA, 1 February 2018

None within its normal range. See Hen Harrier for distinction from that species in Europe where Northern Harrier is a rare vagrant. Southernmost wintering birds in the far north of South America need to be distinguished from Cinereous Harrier; that differs in males with more heavily orange-brown streaked underparts.

Distribution

Widespread in the North America, breeding over most of Alaska except the far north and Canada south of the tree-line. Also breeds over much of the western and northern contiguous 48 states of the USA except for the south and south-east USA. Southernmost breeding limit is northern Baja California. Winters from southern Canada and throughout the USA, and from Mexico to Panama, rarely the Caribbean, Colombia and Venezuela. It has also occurred as a vagrant in the Azores, the Faroes and in Britain.

Taxonomy

This is a monotypic species[1][2].

Formerly treated as a subspecies of Hen Harrier in older versions of Clements and IOC, and still so by Howard & Moore[7], but now split into two separate species in view of the distinct morphological and ecological differences between the two, and the discovery that Northern Harrier is genetically closer to the South American Cinereous Harrier than it is to Hen Harrier[1][2][3][4][5].

Conservation

Northern Harrier populations are secure.

Habitat

Adult female
Photo © by Kibet
Oakland, California, USA, 27 November 2016

Breeds in marshes, grasslands and heathlands, sometimes in mountains, often in cultivated areas.

Behaviour

Flight

Like all harriers, hunts using a low, slow flight over the ground, with their wings held in a shallow "V", then plunge onto their prey.

Diet

Includes small mammals, birds, reptiles, insects, and carrion.

Breeding

They build a nest of sticks and grass on the ground in thick heather, grass or shrubs. The clutch consists of three to six eggs which are incubated by the female for 29 - 31 days, fledging after about a month later.

They take 2 - 3 years to mature, but may attempt breeding in their first year.

Vocalisation

Call: kek, kek, kek

References

  1. Clements, J. F., T. S. Schulenberg, M. J. Iliff, S. M. Billerman, T. A. Fredericks, B. L. Sullivan, and C. L. Wood. 2019. The eBird/Clements Checklist of Birds of the World: v2019. Downloaded from http://www.birds.cornell.edu/clementschecklist/download/
  2. Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.1). doi : 10.14344/IOC.ML.10.1. Available at http://www.worldbirdnames.org/
  3. Simmons, R. E. (2000). Harriers of the World. OUP, Oxford, UK.
  4. Ferguson-Lees, J., & Christie, D. A. (2001). Raptors of the World. Houghton Mifflin Co., Boston, New York.
  5. Dobson, A. D. M., & Clarke, M. L. (2011). Inconsistency in the taxonomy of Hen and Northern Harriers: causes and consequences. British Birds 104: 192-201.
  6. Peterson, RT, G Mountfort and PAD Hollom. 1993. Collins Field Guide – Birds of Britain and Europe, 5th Revised edition. London: HarperCollins Publishers. ISBN 978-0002199001
  7. Dickinson, E. C., & Remsen, J. V., eds. (2013). The Howard and Moore complete checklist of the birds of the world. 4th edition vol. 1. Aves Press, Eastbourne, UK.
  8. Global Raptor Information Network. 2020. Species account: Northern Harrier Circus hudsonius. Downloaded from http://www.globalraptors.org on 8 May. 2020
  9. Birdforum thread discussing the taxonomy of harriers.
  10. Smith, K. G., S. R. Wittenberg, R. B. Macwhirter, and K. L. Bildstein (2020). Northern Harrier (Circus hudsonius), version 1.0. In Birds of the World (P. G. Rodewald, Editor). Cornell Lab of Ornithology, Ithaca, NY, USA. https://doi.org/10.2173/bow.norhar2.01
  11. Cornell Lab of Ornithology. 2019. All About Birds. Cornell Lab of Ornithology, Ithaca, New York. https://www.allaboutbirds.org Accessed on 8 May 2020

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