The Traveler

By Craig Anderson | November 2, 1999
From Missouri Conservationist: Dec 1999

I found my touchstone, the northern harrier, when I was a youngster living in southwestern Minnesota.

In every place that I've lived for any length of time, I've always found that graceful hawk. We've followed each other from the upper Midwest to coastal Virginia and back across the country to the Intermountain West.

After moving to Missouri, I was hopeful that I would see northern harriers, a species endangered in the state. My first year in Missouri passed with no sightings. I was a bit discouraged, but while driving by a prairie in southwestern Missouri, I saw an approaching shape flying just above the horizon, alternating heavy wing beats and buoyant glides.

Occasionally, the bird hovered and then moved on. It looked as if it might be a northern harrier. As it soared closer I could see the characteristic white patch of feathers on the bird's rump. A northern harrier in Missouri--I had reconnected with my touchstone.

I was sure of the species based on its flight pattern and its white rump patch. But to tell if it was male, female or a youngster, I needed to study it more closely. Northern harriers are unusual in the hawk world in that not only are there differences in sizes between males and females, but the sexes have different background colors.

The male is an attractive gray on top with lighter shading underneath and has black wing tips. The female is brown above and buffy with brown streaks below. Immature harriers are similar to females, except they are darker brown above and russet below.

A northern harrier has an unusual feature. When looked at head-on, northern harriers resemble owls: both harriers and owls have a ruff of feathers that makes their faces look flat.

This facial disk focuses sounds from the harrier's surroundings. Unlike many other species of hawks, northern harriers frequently use sound cues, like squeaks or squeals, as well as visual prompts, to locate and capture food.

Around the turn of the century, hawks were divided into two categories by farmers and others--good and bad. Good hawks ate agricultural pests, and bad hawks had a reputation for eating poultry or other livestock.

Farmers generally had a favorable impression of northern harriers because of the species' reputation of eating mice and other rodents. That was a pretty good observation from people who lived close to the land, and one that has since been confirmed by ornithologists, those scientists who study birds.

Northern harriers' diets vary with time of year and in different habitats, but they seem to prefer small to mid-sized rodents. They also will eat reptiles, frogs, small waterbirds and perching birds, like meadowlarks and northern cardinals. Northern harriers, especially recently fledged ones, will even eat insects.

Some raptors, like peregrine falcons, will dive on their prey at high speeds. Others will hover and pounce. Ornithologists have classified northern harrier hunting flights into four types. The first is prolonged, non-flapping gliding, and the second is a more or less straight flight with lots of flapping and little turning. The third type also has a lot of flapping but also a lot of turns over a short distance, while the final type is stealthy and used by a harrier following a landmark, like a fencerow, at relatively low altitudes, perhaps less than 25 feet above the ground.

Regardless of the type of hunting flight that is being used, once a harrier finds a possible food item it will then pounce on the prey and try to catch it. But the success rate of pounces is variable and depends on the habitat, the kind of prey and the age or sex of the harrier. In rough order, it is easier for a harrier to catch a reptile or amphibian than it is to get a small mammal, which in turn is easier than a bird.

For some reason, adult males have higher hunting success rates than adult females, and, of course, just based on hunting experience, an adult will have more success hunting than a juvenile. All of that leads to a pretty obvious conclusion: if a harrier is in tough hunting habitat, is chasing birds and is young, it's going to have to do a whole lot of pouncing to get some dinner.

Even after a successful hunt, a harrier may not eat immediately. For example, if it is during the breeding season and the female is sitting on a ground nest, the male supplies food to his mate. Sometimes, if there is quite a bit of food available, mated harriers will cache supplemental food nearby.

Males announce their territories and court females by executing something that has been called the "sky-dancing display," which can be a spectacular exhibit with as many as 74 U-shaped undulations strung together in flight over a distance of more than a half mile.

The male might fly as high as 1,000 feet or as low as 30 feet. Typically, a display will include about 25 maneuvers about 70 feet above the ground. The males often display over a suitable nesting area.

Once a male and female have tentatively bonded, they will soar together and transfer food in mid-air. The males begin feeding the females when the latter are heavy with eggs.

Another aspect setting northern harriers apart from other hawks is that at least some of the males are polygynous. Those males that end up with multiple mates are the ones who tend to sky-dance the most vigorously. The prevalence of polygyny seems to be tied to the abundance of prey during spring. So, in springs with lots of food, there might be more males with up to five mates than there would be during food-poor years.

Of course, northern harriers don't lead carefree lives of hunting and raising young. There are a number of other animals that would be more than happy to dine on harrier eggs, nestlings, inexperienced fledglings and incubating females. These predators include mammals, such as foxes, dogs, coyotes, skunks and raccoons. Livestock and white-tailed deer can inadvertently step on eggs and nestlings.

Why didn't I see a northern harrier while living in Farmington my first year? There are probably a number of reasons. For one thing, northern harriers are uncommon in Missouri and are listed as endangered because they don't breed much in the state.

Northern harriers breed here and there in western Missouri and at scattered locations across the northern part of the state. People see them more often in the spring and fall as the birds move to and from their winter quarters. So if I missed the spring and fall migrations that first year, my chances of seeing a harrier were low.

The former name for northern harriers was "marsh hawk," which is a pretty good description of where this species generally is found in the midwestern and northeastern United States. Farther west, northern harriers use prairies, cropland and sagebrush plains. East or west, the densest populations of northern harriers generally are associated with large tracts of undisturbed habitat. That sort of undisturbed territory can be hard to find in Missouri and might best be represented by some of the hay prairies in the southwestern part of the state.

Populations of northern harriers are declining in some parts of the country and increasing or remaining stable in other parts. As with many other species of birds, declines may be due to pesticides or other contaminants in the environment, coupled with the loss or degradation of breeding and wintering habitat due to human development. Fortunately, management that is designed to help other species, such as wetland preservation for waterfowl, can be helpful for northern harriers.

This Issue's Staff

Editor - Tom Cwynar
Assistant Editor - Charlotte Overby
Managing Editor - Jim Auckley
Art Editor - Dickson Stauffer
Designer - Tracy Ritter
Artist - Dave Besenger
Artist - Mark Raithel
Photographer - Jim Rathert
Photographer - Cliff White
Staff Writer - Jim Low
Staff Writer - Joan McKee
Composition - Libby Bode Block
Circulation - Bertha Bainer