marsh hawk

from The Century Dictionary.

• noun The common American marsh-harrier, Circus hudsonius, the only member of the Circinæ found in North America: so called from frequenting marshes and wet meadows in search of its prey, which consists chiefly of frogs and other reptiles.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun common harrier of North America and Europe; nests in marshes and open land