The Northern Harrier is a long-winged, long-tailed hawk of open grassland and marshes. It can usually be seen in Edmonds at least once a year and usually hunting over the Edmonds Marsh. But it has also been seen flying over neighborhoods. Unlike most other raptors, each sex of the Northern Harrier looks distinct. The male has a gray head and back and white underside with black wingtips. The female is overall brown. Both have owl-like facial disks that aid hearing. The white rump patch is a distinctive feature of this raptor.
In Washington, the Northern Harrier is a fairly common resident. Birds that summer at more northern latitudes, winter from the southern U.S., through Mexico, into Central America and the northern part of Colombia in South America. The Washington population may seem larger during both periods of migration as migrating harriers move through the state. For the most part, the Northern Harrier migrates alone and during the day. It hunts along the way and that might be why there are occasional sightings of a harrier at the Edmonds Marsh, usually during fall migration.
Diet of the Northern Harrier is mostly small mammals and birds. It specializes in voles, rats, mice and other rodents but will take mammals up to the size of small rabbits. It will also take birds, from the size of songbirds up to the size of flickers, doves and smaller ducks. Occasionally it will eat snakes, lizards and frogs. It hunts by flying low over fields, scanning the ground for prey. It also listens for prey with hearing enhanced by its facial disks. It is said that the male flies faster and closer to the ground than does the female. When the Northern Harrier locates prey in dense cover, it will hover low over the site, as in the third photo, to try to drive prey out into the open.
The Northern Harrier nests in loose colonies. One male may have multiple mates. In courtship, the male repeatedly flies up and then dives in a roller coaster fashion. The female builds the nest, while the male supplies some of the material for it. The nest usually is located on the ground in a dense field or marsh. It is either a shallow depression lined with grass or a platform of sticks, twigs, and weeds.
The female incubates her 4-6 eggs for a period of about one month. She remains with the hatchlings for most of the time, relying on the male to deliver food. The female then feeds it to the young. After the first two weeks, the female does most of the hunting for her young. Age at first flight is about 30-35 days.
The oldest Northern Harrier of record was a female, 15 years and 4 months of age, when she was captured and released in 2001 by a Quebec bird bander. She had been banded in New Jersey in 1986. Two collective nouns for harriers are “swarm” and “harassment.”
The Northern Harrier is fairly common but its population is declining. The population has experienced a 47 percent loss from 1966 to 2014. The current population is estimated at 1.4 million, with 35 percent spending some part of the year in the U.S., 17 percent in Canada, and 10 percent in Mexico. For conservation purposes, the Northern Harrier is considered a species of least concern. It is, however, vulnerable to habitat loss, such as drained wetlands, developed lands for large-scale agriculture, and the reforestation of old farmlands. Since small mammals are a large part of the harrier’s diet, it is susceptible to pesticide buildup as well as to the direct effects of eating poisoned animals.
You can listen to the flight call of a Northern Harrier here: http://www.xeno-canto.org/143657.
— By Carol Riddell
Carol Riddell manages the bird education displays, on behalf of Pilchuck Audubon Society and Edmonds Parks & Recreation, at the Olympic Beach Visitor Station.