Circus hudsonius
Order Accipitriformes
Family Accipitridae
Subfamily Accipitrinae
Other names: Marsh Hawk
♂ Adult male.— Upper parts light bluish-gray; tail crossed by black bars; upper tail-coverts (over the base of the tail) pure white; throat and breast gray; belly white, flecked here and there with brown; under surface of the wings white; wings tipped with black.
♀ Adult female.— Upper parts brown; “rump” white; lower parts buffy-whitish; breast thickly streaked with brown.
Immature.— Upper parts similar to male; lower parts rich rusty, streaked with brown on the breast, paler and unstreaked on the belly.
Nest, on the ground, in wet meadows.
Eggs, white or bluishwhite, often spotted with pale brown.
The Marsh Hawk is a summer resident throughout New England and New York. It winters sparingly in southern New England and the lower Hudson Valley. It arrives in March or April, and stays till October. The usual haunts of the bird are extensive meadows, where it hunts mice and frogs by gliding low over the grass and occasionally dropping to the ground, beating up and down apparently in a regular course. It is found, however, even in the hills, where there are only restricted swampy tracts. In the breeding season the male performs aerial revolutions, dropping from a height, turning, and screaming in his descent. When the nest is approached, the parents swoop at the intruder, uttering cries like the syllables geg, geg, geg. When it flies low, the pure white upper tail-coverts offer an unmistakable field-mark; they are especially conspicuous in the brown birds, the females and immature males. The adult male is a beautiful bird, the delicate gray shade of its plumage and the black-tipped wings suggesting a gull. Sometimes the Marsh Hawk is seen at a considerable height; at such a time its long tail distinguishes it from the Red-shouldered Hawk, and its long wings from the Cooper’s Hawk.
Hoffmann – A Guide to the Birds of New England and Eastern New York (1904)