Northern Gannet | Oceana Canada

Canadian Marine Life Encyclopedia

Northern Gannet

Morus bassanus

Also known as

Gannet

Distribution

Both sides of the Atlantic; from Labrador and Norway south to the equator

Écosystèmes/habitats

Nest on rocky shores & cliffs; feed in the ocean

Feeding Habits

Active (diving) predator

Conservation Status

Not listed

Taxonomie

Order Siliformes (cormorants, gannets & relatives); Family Sulidae (gannets and boobies)

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Northern gannets live the vast majority of their lives at sea, only coming ashore to breed and raise their chicks. They are fast and powerful flyers, but can also glide for hours just above the waves, barely flapping their wings. They are plunge-divers, able to enter the water from heights of more than 30 meters in search of fish. Although most of their dives are relatively shallow, Northern gannets can go as deep as 22 meters, using their large webbed feet and wings to swim down in pursuit of fish. After spotting a fish, gannets will wheel around in the air and dive nearly straight down. Just before entering the water they thrust their wings out straight behind their back in a torpedo-like fashion, allowing them to pierce through the water at incredible speeds. 

Northern gannets are one of the largest seabirds in North America. They are almost completely white, except for their black wing tips. During the breeding season, the whitish plumage on their head turns a saffron-yellow colour. Northern gannets have a strongly pointed beak that is blue-gray in colour and they have striking icy blue eyes. Their black, webbed feet have distinct pale green stripes that run along their foot bone. Young gannets are brown with white flecks, becoming whiter with each passing season until they reach their complete adult plumage at around four or five years old.

In North America, gannets are grouped into six different breeding colonies. These colonies are found along the east coast of Newfoundland and in the Gulf of St. Lawrence, typically on steep sea cliffs, rock stacks and island cliff tops. The largest breeding colony in the world is found just off the coast of Gaspé, Quebec. Gannets come up to these breeding colonies in the early spring and remain there until their young have fledged and can make the journey southward again toward the Gulf of Mexico. Male gannets chose a nesting site at around four years of age, beginning their courtship soon after. Courtship involves potential mates displaying formal dips, bows and spreading of the wings. Once a pair has been established, they will often stay together for many years, returning to the same nesting site year after year. They make their nests out of seaweed, feathers, sticks, moss and debris (such as wasted fishing nets), with droppings and fish skeletons added to the nest pile each year. Between late spring and early summer, females lay one pale blue egg. Both parents take turns incubating the egg with their webbed feet. Chicks hatch after about a month but will remain in the nest to be fed regurgitated fish by their parents. By around September the chick’s flight feathers will come in and the new fledgling will make its way clumsily, half-flying and half-tumbling, to the sea where they must quickly learn from their parents and master the art of plunge-diving for prey. The main prey source of northern gannets are small fish, such as mackerel, capelin and sandlance. They also frequently feed on small squid.

In the 19th century, Northern gannets were harvested off of Newfoundland and Labrador and in the Gulf of St. Lawrence as bait for cod fisheries. This greatly reduced the number of breeding pairs until bird protection laws were put in place at the turn of the century. Although they are not directly targeted by fishers today, they are still affected by fishing activities. As a diving predator, Northern gannets can get tangled and drown in gillnets when they dive down for fish. This has been recorded in gillnet fisheries for Atlantic cod and capelin. Northern gannets also pick up floating debris to build their nests, which can result in entanglements. Once entangled, chicks and adults can die from starvation, however mortality caused by this type of pollution seems to be very low. Interactions between gannets and fishing gear also occurs because, like many seabirds, they are known to follow fishing vessels. Northern gannets pick off fish that are thrown overboard, even taking the fish right out of nets as they are pulled aboard.

Northern gannets have neither been assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) nor listed under the Species at Risk Act (SARA). Their population is considered to be stable in the northwest Atlantic. All breeding colonies in Canada are also protected as provincial reserves or as federal migratory bird sanctuaries.