Birds
Northern Harrier
Circus hudsonius · also called northern harriers, marsh hawk
Gliding low and slow over an open marsh, a northern harrier tilts its owl-like facial disc toward a rustle in the grass below, relying on hearing nearly as much as sight to pinpoint prey hidden from view.
Overview
The northern harrier, Circus hudsonius, is a distinctive hawk native to open grassland, marsh, and other treeless habitat across a broad range of North America. Its owl-like facial disc used for hunting by sound, low and slow quartering flight pattern, and unusual ground-nesting habit make it one of the more behaviourally and anatomically distinctive birds of prey found across the continent.
A hawk that hunts with its ears as much as its eyes
Where most hawks rely almost entirely on sharp eyesight, the northern harrier’s owl-like facial disc gives it a second way to find prey, funnelling the faintest rustle in the grass straight toward its ears.
Status
Least Concern, though showing a decreasing trend in parts of its range linked to the loss and degradation of open grassland and wetland habitat.
Northern Harrier: common questions
Why does the northern harrier have a face like an owl?
This species has a distinct facial disc similar to that found in owls, a feature that helps funnel sound toward the ears, allowing the bird to locate hidden prey by hearing rustling movement in dense grass or marsh vegetation almost as effectively as by spotting it visually, a hunting adaptation unusual among most other hawks.
How does the northern harrier hunt?
This species hunts by flying low and slowly back and forth over open grassland and marsh in a searching pattern called quartering, using both keen eyesight and its owl-like hearing to detect small mammals and birds hidden in vegetation before dropping down to catch them by surprise.
Why do male and female northern harriers look so different?
A male of this species is pale grey overall, while a female is brown, a pronounced difference in colouration between the sexes that is more extreme than in many other hawk species, though the exact reasons behind this particular pattern of difference are not entirely settled.
Where does the northern harrier build its nest?
This species builds its nest directly on the ground within dense grass or marsh vegetation, an unusual habit among hawks, most of which nest in trees, reflecting the species' close overall association with open, largely treeless grassland and wetland habitat.