Birds of Ocracoke: The Northern Gannet

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Morus bassanus

By  Peter Vankevich

If one were to choose a bird that represents the character of Ocracoke–tough, resilient, thrives in windy conditions and loves fish–it could very well be the Northern Gannet.  Seen in the waters around Ocracoke, these large seabirds can appear just off the beach, sometimes in large numbers, plunge-diving for shoaling fish in a spectacular fashion. Fish they like to feed on include herring, mackerel, capelin and sandlance and also squid.

Adults are easily identified by their long sleek shape, including a long bill and tale, white plumage with black wing tips. Their heads are yellow tinged.

Seabirds take several years to come into adult plumage. Sub adults, depending on age, vary from brown the first year to varying degrees of white, especially in the under-wing.

These are fast flyers and can attain speeds of up to 40 mph. The long narrow wings of the northern gannet are positioned towards the front of the body, allowing efficient use of air currents when flying.

Gannets nest in dense colonies called gannetries.  Monogamous for life, they return to the same nest site year after year.  Gannetries are located on steep cliffs and small offshore islands. These sites, for most part, keep land predators from reaching the nesting birds.

In North America there are only six major gannetries–in the Gulf of St. Lawrence, Quebec, and off the coast of Newfoundland. The largest colony, with 32,000 nests, is on Bonaventure Island in the Gulf of St. Lawrence  off the southern coast of Quebec’s Gaspé Peninsula.

In the eastern North Atlantic, there are 32 colonies from the coast of Brittany in France northward to Norway.

When fish are near Ocracoke, gannets can be seen in the hundreds.  They will often follow fishing boats in search of fish in nets and discarded bycatch.

Though gannets can locate fish from as high as 150 feet above the water, they generally search from 30 to 60 feet. When they see a fish, they will dive with their bodies straight and rigid, wings tucked close to the body but extending beyond the tail, before piercing the water like an arrow and hitting the water at speeds of up to 60 mph.

This allows them to penetrate up to 16 ft. below the surface, but they have been known to pursue their prey swimming down to 50 ft.

Since gannets spend so much time in the air and on the water, adults have few predators, though Bald Eagles may occasionally attack them. Eggs and nestlings are vulnerable to being eaten by Great Black-backed and Herring gulls, and in certain land colonies by red fox and short-tailed weasels.   If they can survive the first year, for which has their mortality rate is about 65 per cent, their average life expectancy is about 16 years. Damaged or broken wings are a frequent cause of death in adults. 

Gannets breed when they are full adults at age five and both mates participate in all aspects of parental care. The female lays a single bluish-white egg in nests made of sticks and mud. If the egg is lost, she will lay another — up to three– before they abandon nesting for the season.

Both sexes help with incubation. Since they do not have a brood patch, i.e. a patch of featherless skin on the underside of birds during the nesting season, they incubate the eggs with their vascularized webbed feet, similar to penguins. The average incubation period is 43 days. 

Gannets rest on the water and rarely spend time on land. If one is seen on the beach, it very well may be injured or sick.

The highest number of this bird species recorded in the Ocracoke Christmas Bird Count was 5,306 in 1991.

Listen: 

(audio provided courtesy of OhioLINK Digital Resource Commons)

Best time to see:  mid to late fall, winter to early spring. Migrations north in March off Ocracoke can be spectacular.

Where:  Ocean, ferry routes, Pamlico Sound

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