The hen harrier (Circus cyaneus) or northern harrier (in the Americas) is a bird of prey. The genus name Circus is derived from Ancient Greek kirkos, meaning "circle", referring to a bird of prey named for its circling flight. The specific cyaneus is Latin, meaning "dark-blue".

It breeds throughout the northern parts of the northern hemisphere in Canada and the northernmost USA, and in northern Eurasia. This species is polytypic, with two subspecies. Marsh hawk is a historical name for the American form. The term "hen harrier" refers to its former habit of preying on free-ranging fowl.

It migrates to more southerly areas in winter. Eurasian birds move to southern Europe and southern temperate Asia, and American breeders to the southernmost USA, Mexico, and Central America. In the mildest regions, such as France, Great Britain, and the southern US, hen harriers may be present all year, but the higher ground is largely deserted in winter.
Northern Harrier
Date Location Count
2020-01-20 13:30Beaverdam Creek Reservoir1
2020-01-26 13:40Sully Woodlands1