The northern harrier is scientifically known as circus cyaneus but is also known colloquially as the Marsh hawk. It is a medium-sized hawk, native to North and South America, which receives its common name from its habit of being found in marsh land areas. It is a common species within its range and is seen as more of a help to farmers than a pest because it helps keep rodent numbers down.
The marsh hawk grows to between 18 and 20 inches in height with a wingspan of 40 to 46 1/2 inches and weighs up to 26 1/2 ounces. It is a slender-bodied bird; males have a light gray plumage and whitish chest and belly. Females are darker brown in color and have white lines around the face. The hawk's wings are long, thin and rounded and held in a slight V-shape when gliding. Eyes are yellow as are the legs and the beak is a light to dark brown color.
Habitat and Range:
The hawk is migratory, spending the summer breeding season far north into Canada. Year-round, the hawks live further south in the upper U.S. from the east to west coast. In the winter months some populations migrate down into Central America and into northern parts of South America. The birds are most commonly seen in open areas such as fields, prairies, meadows, marshes and desert scrub land. The birds do return to the outskirts of wooded areas at night to roost and nest.
Diet and Predators:
The marsh hawk is adaptable in what it eats, making use of any small mammalian prey it can find in its home range. Mice, voles and other small mammals make up around 95 percent of the bird's diet, while the rest consists of small snakes, amphibians and birds. The birds sometimes hop around on the ground leaving them open to attack from predators such as foxes, coyotes and feral dogs. On the wing they are at risk from larger birds of prey such as horned owls, while skunks and crows may raid nests for eggs.
Marsh hawks form permanent pair bonds although males will sometimes stray and breed with other females. Because there are generally more females than males a male might breed with up to five females in a season. The female does the majority of the nest building which consists of a platform of vegetation built at ground level. She lays between 2 to 10 eggs in the nest and incubates them on her own. The male feeds the female while she incubates the eggs by dropping dead prey down to her as he flies by. Once the chicks hatch, the male disappears and the female has to feed the offspring alone. After 30 to 35 days the chicks are fully fledged and ready to breed themselves after 2 years. The marsh hawk can live for up to 16 years in the wild.