The northern harrier is underappreciated, I think. I seldom hear it remarked upon, and I doubt it stands very high on many lists of favorite birds. Yet the harrier is a remarkable bird in many ways, with a striking appearance and interesting behaviors that set it apart from other species. What's more, it is widespread, fairly common and easy to recognize. It would likely show up on the daily list of any casual birder who ventured outside the limits of a town, and probably anyone who has ever driven through any substantial area of grassland has seen one, or likely more than one.
The harrier is that slim, long-tailed hawk that moves across the marshland with a kind of rocking flight showing a bright, white rump as it moves away.
A novice birder might think the harrier is two different species, since males and females are different in plumage, though not in body shape and general impression. Males are especially conspicuous, especially in fresh spring plumage, when they are a ghostly gray on the topside and immaculately white below. The wing tips are black. Females are a warm brown color, mottled overall, appearing darker than males but by no means black. Both species display the white rump, at the front edge of the tail directly behind the wings. This, and the flopping kind of flight, is the best field mark of the harrier.
At rest, the harrier shows this field mark, too, though harriers are seldom seen at rest. They nest on the ground in dense cover and have little incentive to show themselves on fence posts or hay bales. They are not still hunters, sitting in wait for prey, as kestrels and even red-tailed hawks often do. Instead, the harrier hunts on the wing.
The harrier is a deliberate hunter, eyes downcast, occasionally pulling up, wheeling back and dropping into the grass. At such moments, you can be pretty sure the harrier has found prey. Failing to find prey, the harrier will likely double back, checking out the grassland yet again. I have watched many times as a harrier moves across the few acres of grassland that we own amid the soybean fields of Wheatfield Township northwest of Grand Forks. The bird inspects the territory, wheels about when it reaches the tree line that marks the edge of an adjoining field, and retraces its path, perhaps shifting its position just a little to increase the chance it will spy something it missed on its first pass.
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Or, perhaps, the birds are listening. The technical literature tells me that harriers are equipped for echolocation, as owls are. The disk-like arrangement of feathers on their faces-visible at close range-apparently helps channel sounds to their ears, a characteristic shared with owls. Owls, of course, hunt mostly at night while harriers are active in daylight.
The literature also notes that males hunt over more widely, more open territory than females do, and that males provide all of the food to incubating females and most of the food until nesting harriers are up to two weeks old. The hen's nesting obligation probably accounts for the difference in plumage between the species. A mottled brown bird is harder to spot in grassland than a striking gray and white on the male birds. Males don't do any incubating of eggs at all.
Harriers court on the wing, as well, and their bonding ritual involves aerial loops, close passes and food exchanges. Evidently, the male proves his capacity as a hunter at this critical moment. The birds are monogamous, but males often desert the nests once the young near fledging stage. This isn't a case of philandering, though; the literature suggests that "desertion is probably influenced by male physiological condition" (Birds of North America monograph). In other words, the male is simply worn out.
The northern harrier occurs throughout the Northern Hemisphere, pretty much everywhere in North America except urban areas and Arctic tundra. It is as characteristic of English fens and Russian steppes as it is of the American Great Plains. In Britain, it is called hen harrier.
Many early American bird books called this species marsh hawk, including Robert Stewart's "Breeding Birds of North Dakota," published in 1975. This name evokes its habitat; the more recent name places it squarely in a worldwide group of birds.
It is the only species in its genus that occurs in the North America. About a dozen species occur worldwide, mostly in Eurasia but also in Africa and Australia. The single South America species is similar to the northern harrier, but with heavily barred underparts.
The word harrier has another, perhaps more immediately recognizable meaning. It's the name of an airplane developed by a British company and used by military organizations, including the United States Marine Corps.
And yes, the airplane is named for the bird.
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