Northern Harriers © Dave Spier

A Northern Harrier hunts at Muckrace Flats beside Savanah Spring Lake Road northeast of Savannah, NY during the 2010 Muckrace.  (Photo © Dave Spier)

The Northern Harrier, once known as the marsh hawk, is a slender and buoyant raptor with a somewhat owl-like face. The hawk's long wings and tail are designed for life in the open. A distinctive white rump patch can be seen when the bird's flight tips sideways toward you, or, sometimes, the white can be seen as the bird departs. When soaring, the wings are held in a shallow V with the tail fanned. At low altitudes, the tail is usually closed and the wings may be held flat to the sides. In a steep glide, the wings are sharply bent and swept back like a fighter jet.
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 of the story because females and juveniles are brown or orangish, an unusual disparity for raptors. 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 smaller birds. The larger females are more intent on larger meals.
Harriers nest in the marshes at Montezuma National Wildlife Refuge. One April I watched a female repeatedly carry nesting material in her beak and then drop down into the same patch of heavy vegetation. There are indications harriers also may nest in the Northern Montezuma Wetlands Complex around Savannah. They almost certainly nest in the Lakeshore Marshes Wildlife Management Area in northeastern Wayne County as well as Howland's Island. The female does all the incubating while the male brings food. After the eggs hatch, the male continues supplying prey, but only the female tears it up and feeds the young. If something happens to her, the nestlings will starve, even though the male continues to drop whole prey into the nest.
Harriers breed from Alaska across Canada to the Maritimes and south into the United States as far as a line from California to Pennsylvania. In warm weather they hunt snakes, frogs and insects in addition to small mammals. When all else fails, carrion is eaten.
Last fall, a young harrier spent some time at the Montezuma Audubon Center. Sometimes it flew close to the building, passing the west windows and then disappearing across the field. I doubt it was hunting the birds at the feeder, but they are within the realm of this raptor's diet. Mostly it flew low over the grasslands and the marsh while looking for small mammals, especially Meadow Voles (also called field mice) which are caught with a sudden pounce. Sometimes the large bird's flight drifted back and forth, then stopped momentarily to hover. After hanging around for several weeks, the first heavy snowfall of the season didn't seem to phase it, but it did finally move on. Most harriers head south for the winter and return in the spring. Those that do stay for the winter 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 they are unrelated species, the facial disks of both harriers and owls seem to help focus sounds on the ears.