The Northern Harrier
   Circus cyaneus
 

http://www.buteo.com/nharrier.htm
 
 

What is a northern harrier?
What does the northern harrier look like?
Where does the northern harrier Live?
What are the northern harriers special characteristics?
What is the role of the northern harrier in the Salt Playa food web?
Bibliography


What is a northern harrier?

The northern harrier, Circus cyaneus, was formerly known as the marsh hawk.  It is in the order Falconiformes, and the family Accipitridae.  Its order implies that it is an accipiter.  An accipiter is a relatively large bird of prey that is characterized by its thin tapering wings which allow it to be fast, agile and to perform great maneuvers and capture prey.  Accipiters fly with their wings in a dihedral formation which is unlike any other family of birds. 

What Does the northern harrier look like?

The northern harrier has a long tail and long narrow wings.  It has long, yellow unfeathered legs which allows it to stand in the tall saltgrass while hunting.  Northern harriers have yellow eyes, and a yellow cere.  Males, females and juveniles markings differ.  Males are pale gray with streaks of white, the tail has brown bars on it.  Females are dark brown with lighter brown and white streaks and the tail has brown bars.  Juveniles resemble females but have a cinnomon brown colored breast.  There is a white patch near the rump on all, males, females and juveniles-which is dianostic for the species. 

The northern harrier is similar to the short-eared owl, but it should not be confused with it.  The owl has a dark colored rump, and it is a sit and wait predator.  It often shares the same habits as the northern harrier, but it does not glide low to the ground, above its prey. 

Where does the northern harrier live?

The northern harrier lives as far north as Alaska spans across the northern and the western United States during the summer months.  In the winter, the northern harrier has been sighted as far south as Mexico, and can be seen anywhere in the United States.  Circus cyaneus lives in grasslands, marshes and wet meadows.  It nests in tall grasses and shrubs, usually low off the ground.  Each pair of northern harriers must have at least 250 acres of habitat in which they can find their food.
 
 

Relative Abundance Map:  www.mbr.nbs.gov/bbs/grass/h3310ra.htm 








The Great Salt Lake Playa provides the perfect habitat for the northern harrier.  Not only because it has the necessary land but also the animal diversity that the northern harrier relies on.  The climate is ideal and the Northern Harriers do not have to migrate from the playa.  The northern harrier can be seen at several locations around the Great Salt Lake year round.  Some of these locations include Bear River Bay (controlled by the U.S. Fish and Wildlife Service) , Ogden Bay, Layton Marsh, (which is run by The Nature Conservancy), Farmington Bay, and the Inland Shorebird Reserve (established by Kennekott Copper Corporation), near Magna, Utah on the south shore of the Great Salt Lake.

What are the northern harrier's special characteristics?

Northern harriers actively hunt for voles and other small mammals and insects such as grasshoppers around the salt water marshes where saltgrass is prevalent.  Grasshoppers are an important but alternative source of food.  Northern harriers are so dependent on voles that one researcher has named them "the hawk that is ruled by a mouse."  In the winter months when vole and grasshopper populations are low, northern harriers can be seen catching smaller birds.  Among these birds are the savannah sparrow, snowy plover, and other seasonal birds.  These seasonal birds prefer to nest in the saltgrass off the shore of the Great Salt Lake, making them easily accessible for the northern harrier to prey on.

The northern harrier has keen eyesight and hearing.

Northern harriers have strongly hooked bills and very powerful talons, which are useful in capturing and eating prey.

The northern harrier has an owl-like facial disk which reflects sound when combined with its characteristic low flight (<7').  It is the only bird of prey, other than owls with a facial disk.   The facial disk allows the harrier to locate prey in grasses, shrubs and underground. 

The northern harrier's voice is recognized by its rapid and descending cheek-cheek-cheek sound.

The northern harrier is 17-24 inches tall and has a 42-44 inchwing span.
 
 


http://www.buteo.com/nharrier.htm







What is the role of the northern harrier in the Salt Playa food web?

Many people believe that an increase in predator numbers causes a decrease in prey populations.  This idea is often misleading.  The population of northern harriers is probably limited by the amount of prey available for consumption on the Great Salt Lake Playa.  The number of plants and seeds that voles and other small mammals feed on is directly related to their population.  The availability of food for voles and small mammals is controlled by the weather and the amount of rainfall in the area.  When vole populations are soaring they allow for northern harriers to proliferate and the harrier numbers grow. 

Under normal circumstances the northern harrier male will take only one mate, but when conditions are ideal, the male will take multiple mates and increase harrier populations even more.  The female establishes the nest, and the males tend to it.  This is a characteristic that is unique among North American hawks. 

The northern harrier is not a controlling factor for the voles, but the voles are  most likely the controlling factor for the harriers.  Therefore, the climatic cycles may have a great influence on the northern harrier populations around the Great Salt Lake.

For more information contact Hawkwatch International or The Raptor Center.
 

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Bibliography

Ehrlich, Paul R.; Dobkin,David S.; Wheye, Darryl; The Birder's Handbook,  Fireside, Simon & Shcuster Inc., New York, 1998.

The Raptor Center, Northern Harrier (no author found)
www.raptor.cvm.umn.edu/raptor/rfacts/nharr.html

Texas A&M University (no author found), Northern Harrier, Circus Cyaneus
www.glo.state.tx.us/wetnet/species/harrier.html

Northern Harrier (Circus Cyaneus), (no author found)
http://home.earthlink.net/~lucretius/nharrier.html

Jim Hines, Northern Harrier, Circus Cyaneus Relative Abundance Map-BBS
www.mbr.nbs.gov/bbs/grass/h3310ra.htm

Greg Gothard, Northern Harrier, 1997.
http://www.buteo.com/nharrier.htm