Northern Gannet

The Northern Gannet is the largest seabird breeding in the North Atlantic, a striking white bird with black wingtips and a buff-tinged head. It is best known for its dramatic feeding technique: spotting fish from high above, it folds its wings and plunges into the sea like an arrow, hitting the water at high speed and using the momentum to reach prey well below the surface. Air sacs beneath the skin cushion the tremendous impact.

Gannets are colonial breeders that gather in enormous, densely packed and noisy colonies, or gannetries, on cliffs and offshore stacks. The species has recovered strongly over the past century after historical persecution, and colonies such as those in Scotland now hold tens of thousands of pairs. Outside the breeding season the birds disperse widely across the Atlantic, with younger birds ranging as far south as West Africa.

An adult Northern Gannet is unmistakable: a large, cigar-shaped white seabird with long narrow wings tipped in black and a golden-buff wash over the head and nape. The bill is long, pale and dagger-like, and the eye is pale with a dark surround. Young birds are dark brown speckled with white and take several years to acquire full adult plumage.

At sea gannets are mostly silent, but colonies are deafening. Birds give harsh, rhythmic grating and cackling calls, often rendered as a repeated urrah or rah-rah-rah, as they defend nest sites and greet returning mates. The constant chorus of thousands of calling birds, mixed with wind and surf, is a defining feature of a gannetry.

The Northern Gannet breeds on both sides of the North Atlantic, with the great majority of colonies in the eastern Atlantic around Britain, Ireland, Iceland, Norway and France, and smaller numbers on islands off eastern Canada. It nests on steep sea cliffs and rocky stacks, and outside the breeding season ranges across the open Atlantic, moving south to waters off Iberia and West Africa.

Gannets are specialist fish-eaters, taking shoaling species such as herring, sand eels, mackerel, capelin and pollack. They hunt by plunge-diving from heights of up to about 40 metres, hitting the water at speed and often continuing to swim downward to seize prey. They forage both alone and in large flocks over fish shoals, and readily follow fishing boats for discards.

Pairs nest in tightly packed colonies on cliff ledges and flat stack tops, building a mound of seaweed, grass and debris cemented with droppings. The female lays a single pale egg, which both parents incubate by wrapping their webbed feet around it. Both adults feed the chick, which grows fat before fledging and leaving the colony to make its own way out to sea. Gannets are long-lived and typically return to the same colony each year.

• Cape Gannet: Southern African relative, very similar but with a longer black throat stripe
• Masked Booby: Tropical seabird with a similar white-and-black pattern but a dark face mask and different range
• Great Black-backed Gull: Large pale seabird often seen in the same waters but broader-winged and gull-shaped, not a diver