The northern harrier (Circus hudsonius), also known as the marsh hawk or ring-tailed hawk, is a bird of prey. It breeds throughout the northern parts of the Northern Hemisphere in Canada and the northernmost United States.

The northern harrier migrates south in winter, with breeding birds in Canada and northern Great Plains of the U.S. moving to the American south, Mexico, and Central America. In the midwestern, mountain west, and north Atlantic states of the U.S., they may be present all year. This bird inhabits prairies, open areas, and marshes.

Taxonomy

In 1750 the English naturalist George Edwards included an illustration and a description of the northern harrier in the third volume of his A Natural History of Uncommon Birds. He used the English name "The Ring-tail'd Hawk". Edwards based his hand-coloured etching on a bird collected near the Hudson Bay in Canada and brought to London by James Isham. When in 1766 the Swedish naturalist Carl Linnaeus updated his Systema Naturae for the twelfth edition, he placed the northern harrier with the falcons and eagles in the genus Falco. Linnaeus included a brief description, coined the binomial name Falco hudsonius and cited Edwards' work. The northern harrier is now placed in the genus Circus, introduced by the French naturalist Bernard Germain de Lacépède in 1799. The genus name Circus is derived from the Ancient Greek kirkos, referring to a bird of prey named for its circling flight (kirkos, "circle"). The specific epithet hudsonius is from "Hudson Bay", the type locality. The species is monotypic: no subspecies are recognised.

Description

thumb|left|Juvenile flying at [[Bosque del Apache National Wildlife Refuge, USA]]

thumb|left|Female in flight at the Llano Seco Unit of the [[Sacramento National Wildlife Refuge Complex in California]]

The northern harrier is

The northern harrier is mostly silent, although males and females will both give fast kek notes that will last 1-2 seconds. When faced with predators or surrounded by smaller birds, they still emit kek notes but at a higher pitch. During the mating season, the female emits a loud scream, which causes the male to either mate or provide food.

Behaviour

This medium-sized raptor breeds on moorland, bogs, prairies, farmland coastal prairies, marshes, grasslands, swamps and other assorted open areas. as do most harriers. Preferred prey species can include voles, cotton rats and ground squirrels. Up to 95% of the diet comprises small mammals. Larger prey such as rabbits and adult ducks are taken sometimes and harriers have been known to subdue these by drowning them in water.

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  • Northern Harrier Species Account – Cornell Lab of Ornithology