Northern Harrier––An owl-like hawk with a breathtaking courtship display
Raptors are famous for dramatic and aerobatic courtship displays, and to my eyes, the northern harrier wins the gold. The extraordinary sky dance of a male harrier is among my favorite spring spectacles, and recently I was treated to an exceptional show.
Flashing silver and white, the harrier advertised for a mate in undulating nonstop spirals continuing for almost a mile over his territory in the Nome River valley. He repeatedly climbed hundreds of feet into the air, then tumbled nearly to the ground, twisting and twirling, wing-over-wing, upside down in dizzying, rollercoaster flight. It was a solo performance, but sometimes a female will join these jaw-dropping displays.
When not performing for a mate, the harrier is still distinctive in flight. This medium-sized hawk with a slender, long-tailed profile hunts low to the ground, gliding on broad wings, held in a slight vee. Males and females are colored differently, but both show an eye-catching white rump-patch when flying.
Harriers are buoyant and somewhat owl-like as they course over the landscape in search of prey. Like owls, they rely heavily on their hearing as well as vision to detect hidden prey. Their faces are even owlish, surrounded by stiff facial feathers that they can raise to direct sound to their ears, as owls do.
Northern harriers occur widely across North America’s grasslands and wetlands. In this region they typically arrive in early May as breeders, summer visitors and passing migrants.
They range over the entire Seward Peninsula but are birds of open country. They prefer meadow habitats interspersed with dwarf shrubs, especially next to wetlands. They are often seen coursing low over the tundra and hunting the edges of wetlands for voles and small birds.
Harriers nest on the ground, hidden by dense grasses or shrubby, wetland vegetation. Together, the pair collects sticks and branches to build a substantial nest platform. Sometimes the platform is over wet ground or shallow water, which may help deter predators. The female lines the nest with grasses and sedges. It can take a pair up to two weeks to build the bulky nest, which can be up to eight inches high and two feet wide.
These hawks don’t defend large territories, but the pair teams up to aggressively protect their vulnerable ground nest from predators. And males drive away other male harriers, while females chase away female intruders.
Usually, male northern harriers are monogamous and have only one mate per season. But they are an unusual raptor that may have up to five mates, if prey is very abundant.
Females typically lay three to six eggs. When prey is plentiful, clutches are larger. Males hunt and provide most of the food for their mates and their offspring, while the female incubates and broods the chicks.
Females begin hunting as soon as their downy young can maintain their own body temperature. This helps ensure the nestlings have adequate food in the event their father has more than one mate and clutch to feed.
The young venture from the nest in about two weeks and move about through the surrounding vegetation, where the parents find and feed them. They fledge in about 31 to 38 days.
Photo by Kate Persons
JUVENILE HARRIER – A juvenile northern harrier is hunting along the edge of Safety Sound. Juveniles look similar to females but are usually more orange in color. Note the owlish-looking face, which is surrounded by stiff feathers that the hawk can raise to direct sound to its ears, as owls do. Safety Sound is a good place to see young harriers hunting voles and small birds in September.
Harriers hunt almost entirely on the wing, flying low and slow in a relaxed fashion. Bouncing and dipping, tipping and wheeling, they course buoyantly over the open landscape, watching and listening intently for small mammals and birds. Long legs and sharp talons are well suited for snatching prey out of dense vegetation. They eat their catch on the ground.
Voles are the harrier’s most important prey item. The number of breeding pairs and the harrier’s nesting productivity are strongly tied to the availability of voles. But they can take larger prey too, sometimes by drowning it. Ptarmigan, grouse, ducks, ground squirrels and hares are occasional items on their menu.
They also eat insects and carrion and sometimes steal food from other raptors, which they harass, causing them to drop their prey. The harrier then swoops down and grabs it. This is called kleptoparasitism.
Photo by Kate Persons
FEMALE HARRIER – A female northern harrier is carrying a willow stick for nest building in the Nome River valley. Females are a rich chocolate brown with buffy markings on the head. Note the obvious white rump patch that all harriers have. Females are 50 percent heavier and 12 percent larger than males.
Most adult harriers leave the region during the last half of August, while some juveniles may stay until late September.
A few harriers winter along the coastlines of southwestern and southcentral Alaska, but most migrate south to Canada and the Lower 48 states, with some migrating as far as Central America and northern South America.
They winter in areas of open country with little snow cover, such as farmlands and wetlands. During most of the year harriers are solitary. But in winter, if food is plentiful, 80 to 90 harriers may roost close together, sometimes with short-eared owls. That would be a sight to see!
Harriers are still fairly common, but the species is estimated to have declined by about 34 percent between 1966 and 2019. Habitat loss resulting from conversion of wetlands and grasslands to agricultural fields is thought to be the main cause of their decline.
Pesticides are another factor, which kill small mammals and reduce food availability. And when a harrier eats small mammals that carry toxins from pesticides, the toxins build up in the harrier’s body, which can eventually kill it or hinder reproduction. Harriers declined dramatically in the mid 20th century due to DDT poisoning, but rebounded when DDT was banned in the 1970s.
Harrier numbers in Alaska are not tracked. The issues responsible for declines in the southern part of the harrier’s range are not factors in Alaska. But climate change is already altering tundra and wetland habitats, which could change or eliminate large areas of harrier habitat.
Harriers seem to be here in good numbers this spring. Keep an eye out for these low-flying, white-rumped raptors that are courting, nest building and hunting now.