In the Americas, the Hen Harrier is better known as the Northern Harrier.
These raptors breed throughout the northern parts of the northern hemisphere in Canada, northernmost USA, and in northern Eurasia. For the winter, those breeding in the Americas migrate south to the southern parts of the USA, Mexico and Central America. European populations spend the winter in southern parts of Europe and in southern temperate Asia.
Those found in temperate climates are often resident (non-migratory).
The Hen Harrier measures about 16 - 20 inches (41 - 52cm) in length, and has a wingspan of about 38-48 inches or 97-122 cm. The average weight is 19 oz or 530 grams. Males are generally a little heavier.
The European males is mostly grey above and whitish below. The exceptions are the grey upper chest, the white rump and the grey, black-tipped wings. The females are brown above with white upper tail feathers. Below they are buff streaked with brown. The females also have darker, more rufous-colored plumages.