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Fast Facts: Great blue heron

Scientific name: Ardea herodias
Average weight: Just over 2 kg
Average height: 1 m
Average lifespan:

Did you know?

More than 1,000 great blue herons nest each year on La Grande Île in Lac Saint-Pierre near Montréal.

Physiology

The largest heron in North America, the great blue is mostly grayish blue. Some of its body parts are more colourful: its eyes are yellow, its legs are green and its head is white. A black stripe marks each side of its head. A few shaggy black plumes stick out from its back.

The birds’ feathers turn brighter during mating season and dingier in winter. Females look like males but are smaller.

These herons usually hold their neck in an “S” curve when flying.

Habitats/Behaviours

Water and land are both necessary for this bird. Either salt or fresh water can serve as its fishing grounds, but the birds need islands or woody swamps nearby so they have a place to build their nests.

The birds build one-metre-wide nests out of dry sticks, sometimes lining the bottom with pine needles or moss.

Herons choose a new mate each year. The female lays about three to five eggs, which she sits on at night. The male sits on them during the day. Once the chicks hatch, the parents continue to share duties: mom watches the nest at night and dad takes the day shift.

By about eight weeks old, the young birds start to fly. At 10 weeks, they leave the nest – and their parents – for good.

Then they’re ready to start acting like adult herons. They stand perfectly still in the water until a tasty morsel passes by. Usually it’s a fish, but sometimes a heron will eat other water life, or even another bird.

When they see something — wham! The heron lunges with its body and neck. If it nabs the prey, the bird usually tries to swallow it in one gulp, sometimes choking in the process.

Range

Great blues are Canada’s most widespread heron, from the Maritimes to British Columbia. There are probably tens of thousands in the country, although west coast populations may be at risk due to the area’s growing human population.

Most head south once water begins to freeze. Some fly as far south as Mexico or Cuba. In parts of B.C. and the Maritimes, some remain all winter.

These birds are also common through most of the United States and Mexico.

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