Saturday, October 22, 2011

The Northern Harrier, once known as the "marsh hawk," is what I call an Adirondack peripheral species more common around the edges. It's a slender and buoyant hawk with a somewhat owl-like face. The hawk's long wings and tail are designed for life in the open. If it tips toward you, look for the distinctive white rump patch. When soaring, the wings are held in a shallow V (called a dihedral) with the tail fanned. At low altitudes, the tail is usually closed and the wings held flat to the sides. In a steep glide, the wings are sharply bent and swept back like a fighter jet.

Mostly it flies low over the grasslands and the marshes while it looks for small mammals, especially Meadow Voles (also called field mice) which are caught with a sudden pounce. Sometimes this large bird's flight drifts back and forth, then stops momentarily to hover before pouncing. In warm weather it hunts snakes, frogs and insects. When all else fails, carrion is eaten.

Male Northern Harrier eating prey (probably a vole) in a field -- © Dave Spier

In the winter, harriers hang around with Short-eared Owls and share the same fallow, grassy fields where mice have had time for a population explosion. Both species will use fence posts for hunting perches as they listen for prey. Though unrelated species, the facial disks of both harriers and owls seem to help focus sounds on the ears.

The harrier's Latin name, Circus cyaneus, refers to its circling flight and the supposedly blue plumage of the males. The color is actually gray, but that's only half the story because females and juveniles are brown, an unusual disparity for raptors. The bodies of juveniles are orangish underneath. The name harrier is Old English for "harassing with hostile attacks." Other colloquial names include blue hawk, mouse hawk and white-rumped hawk. Males are smaller and more agile and catch smaller prey, including birds.

Female Northern Harrier (note the white rump) over a marsh -- © Dave Spier

Harriers breed from Alaska across Canada to the Maritimes and south into the United States as far as a line from California to Pennsylvania. The 2000-2005 N.Y.S. Breeding Bird Atlas contains 32 breeding records for harriers in the core Adirondack region (not counting the Champlain lowlands). Of these, six are confirmed, three more are probable and 26 are possible. There is a heavy concentration of harrier breeding records in the St. Lawrence lowlands of northern Jefferson County. In fact, the Adirondacks are surrounded by numerous records including the Champlain area.  (Click for a map)

Most harriers head south for the winter and return in the spring, but a number of birds, likely adults with good hunting skills, will stay in the north (see the previous post about the Fort Edward Grasslands Important Bird Area).

[bold blue type indicates a link]  Contact me at

Male Northern Harrier tearing apart prey in a field -- © Dave Spier

No comments:

Post a Comment