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Elizabeth Walsh - Nature Notes

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One of my favourite birds of prey is the northern harrier. In flight the Harrier is easily identifiable by its white rump, and it is the only medium-sized hawk to routinely fly with its wings angled upward.

The Northern Harrier is best spotted over open agricultural lands such as hayfields, meadows and marshes. The bird flies low over the vegetation, trying to spot possible prey and make a surprise attack on it. Because of its preference to marshlands, the Northern Harrier was once called the "marsh hawk" and still is by some here in North America.

The male is bluish-grey on top and white underneath, while the female is dark brown above and light brown below streaked with darker brown. Both sexes have long wings with black tips, a long tail, and a white rump visible in flight.

In courtship, the aerial display of the male harrier is an impressive sight to see. When the male spots a female that he would like to impress, he flies vertically into the sky, where he will then pause, fold his wings back, and plummet recklessly toward the ground. The downward dive may be filled with somersaults and rollovers and just at what seems to be the last second, he saves himself from crashing into the ground and will then fly straight again to repeat his performance. Once he catches the attention of the female, she will fly up to join him and together they will fly, dive, and somersault away.

Northern Harriers return to their breeding grounds in late March to early April. Unlike many other birds who return to the same breeding territory as the previous year, the Harrier does not necessarily do this. They will readily change their breeding territory to an area with more abundant food, particularly where there are a large number of voles.

Harriers also change their mate each year. Typically a male will only have one mate per breeding season but some males will have two or more mates. When this occurs each of his female partners will establish a nest site within a portion of the male's territory.

When forming their pair bond, the sky dance (as described earlier) is only a portion of what the male attempts to do to impress his mate. An extremely important part of the courtship behaviour is for the male to provide food to his female partner. The female chooses her mate based on the abundance of food the male can provide for her.

The nest is built on the ground in old fields, marshes or meadows sometime between late April and early June. Typically the harrier, preferring wet areas, will build her nest on elevated platforms of grass and cattail. Harriers will also make a depression on the ground which they will line with trampled vegetation. Once constructed, the nest my measure up to one metre in diameter.

The female lays four to six nearly-white eggs. She begins incubation immediately after the first one is laid and the first will hatch about 30 days later. During incubation she remains on the nest for the majority of the time while the male brings her food. Since incubation starts as soon as the first egg is laid, the chicks will be of different size when they hatch. Often the smallest chicks will not survive, as the larger ones will take the majority of the food.

The chicks will be brooded by the female for two weeks after they hatch. At this time she will stand over them with her wings spread to shelter them from the sun and rain. The male will bring food to his family during the first two weeks. When he is above the nest, he will drop the food and the female flies up to catch it. The female will then tear the food into smaller pieces to feed to her young.

After two weeks, the chicks will start to wander about the nest and both parents will actively hunt for their chicks. At four weeks, they will begin to fly short distances and will shortly begin to fly out to meet their parents returning to the nest with food.

The young will stay with their parents until the fall when they will learn to hunt for themselves.

Elizabeth Walsh is a Miramichier and expert on all things natural. She shares her love of Canada's plants, animals and birds in this column.