Vancouver Avian Research Centre

.....Research - Conservation - Education

Species : Northern Harrier  Circus cyaneus 

   

Description: 

The Northern Harrier is a common raptor of open wetlands, fresh and saltwater marshes, meadows and upland grasslands.  Its long tail, white rump and low relaxed flight are distinctive. 

In Europe and Asia it is called the Hen Harrier or Marsh Hawk.  This species is widespread, breeding throughout North America and Eurasia.  It is widely but locally distributed in North America (primarily south of tundra) when breeding. It winters in parts of the U.S., the pacific coast of B.C., Mexico, Central America and parts of the Caribbean. 

Identification: 

General:  A slim, long tailed, long legged hawk, which is strongly sexually dimorphic.  Females are much larger than males.  The white patch on the uppertail coverts is diagnostic along with its distinct facial disk.   Length: 41-50cm.  Wingspan: 97-122cm. Weight: Male 346g, Female 496g. 

Adult Male:  Dark gray head, back, breast, upperwing coverts and uppertail. Distinct facial disk.  From below appears overall white with dark gray head and neck with black tips on primaries and secondaries forming a black band on trailing edges of wings.  The rump is white and clearly visible in flight.  Eyes are yellow. 

Adult Female:  Dark brown head, which gives a hooded look, especially in flight. Distinct facial disk.  Back and upperwing coverts are brownish.  Buffy underparts are heavily streaked dark brown.  From below there are noticeable white bands through secondaries and the long tail shows even-width dark and light bands when spread. Rump is white and clearly visible in flight. Eyes are yellow. 

Juveniles:  Similar to adult females but have rufous underparts with dark streaking on upper breast and sides.  By spring, colour of underparts fades to creamy.  Eyes are dark brown on female juveniles and pale gray-brown on male juveniles. 

Similar Species:  The Northern Harrier can be mistaken for many other raptors.  However, its long tail distinguishes it from shorter tailed falcons.  Its slender body also distinguishes it from heavier bodied hawks like the Rough-legged Hawk.  And, its distinctive flight, white rump and facial disk are keys to identification. 

Behaviour:  Flies low over marshes and fields while hunting with languid, heavy wing beats.  Wing beats are followed by a short glide, with wings held in a strong dihedral and teetering from side to side.  Drops quickly on prey in grasses or marsh.

Perches on stumps and fence posts and occasionally the ground.  Eats rodents, small birds, insects, and snakes. 

Habitat:  Open wetlands, fresh and brackish marshes, grasslands, tundra and farmland. 

Information: 

The Northern Harrier is a specialized ‘mouser’ in tall vegetation.  It catches prey by sound as well as sight.  Its owl like facial disk of facial feathers may function to help locate sounds. 

Birds may roost communally on the ground when not breeding. 

Nest is a platform of sticks and grasses lined with fine materials placed above water or on a knoll on the ground.  3-9 eggs of bluish white, sometimes with dark marks, are laid. 

Conservation: 

Declining wetland and undisturbed grassland habitat is causing concern but is presently classified as of “least concern”.
 
Capture Rates


An infrequent but not rare sighting at Colony Farm, the Northern Harrier uses the open grasslands of the park to hunt. Low capture rates (2010-2012; standardized as birds captured per 100 net hours) are indicative of the infrequent visits to the banding area.

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