The Hamerstroms also conducted a decades-long study of the northern harrier. The northern harrier is long with a wingspan. Common birds include sandhill crane, Wilson's snipe, long-billed curlew, and northern harrier. Seasonal birds of prey include the bald eagle, peregrine falcon, and northern harrier. Northern harrier, has been seen in the spring. Berry's Creek harbors the last remaining northern harrier nest site in the Meadowlands. The canyon also has raptors including northern harrier, Cooper's hawk, golden eagle and peregrine falcon. Ospreys, bald eagle, northern harrier, short-eared owl and barn owl nest on the refuge. The northern harrier ("Circus hudsonius") is a bird of prey.