The Northern Gannet (Morus bassanus) is the largest seabird in the northern Atlantic, a powerful white diver with black-tipped wings and a yellowish crown. It is a specialist of the North Atlantic, breeding on remote sea stacks and cliffs before ranging across the ocean to forage on schooling fish. Its most dramatic behavior is the plunge-dive, where it folds its wings and strikes the water at over 100 km/h to catch prey like mackerel and herring.
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Adult Northern Gannets at a breeding colony (Bass Rock, Scotland).
Learning lesson · openly licensed photographs, labelled by BirdBot; labels checked against the cited sources and approved by AI
Buff-yellow head: brighter in the breeding season. Blue eye-ring: set in black bare skin. Spear-like bill: blue-gray, with a black line to the face. Black wingtips: dark primaries on otherwise white plumage. White body, black tips, buff head: an adult gannet.
Young birds are gray-brown and take years to turn white.
Sources: Audubon Guide to North American Birds: Northern Gannet · Wikipedia: Northern gannet (revision 1383090268)
Photo: Odd Wellies, CC BY 2.0, via Wikimedia Commons; labels added by BirdBot.
Adult Northern Gannets are unmistakable in the northern part of their range, characterized by their large size and striking coloration. They are predominantly white with black tips on their wings and a yellowish crown and nape. The bill is stout, straight, and pale blue with black nasal grooves and a serrated mandible. The face has blue-gray skin, and the eye is surrounded by a bright blue orbital ring with a pale blue-gray iris.
Sexes are similar in plumage, but males are slightly larger. A subtle field mark is the line running down the front of the leg and onto the toes: it is yellow-green in males and bluish-green in females. Males measure 93 to 110 cm in length, while females are 92.5 to 104 cm. Females also tend to be heavier on average (3067 g) than males (2932 g).
Juveniles look quite different from adults. They are gray mixed with white feathers, with a V-shaped white patch on the rump. Their bill, legs, and feet are black, and they have bluish-gray eyes. As they molt, more white plumage develops, starting from the lower body and moving upward. Full adult plumage takes 3 to 4 years to develop. In the southern part of their range, they may be confused with Masked Boobies (Sula dactylatra) or Cape Gannets (Morus capensis), but in the north, they are unlikely to be confused with other seabirds, though they might be mistaken for shearwaters at a distance.
Northern Gannets inhabit coastal marine waters on the west and eastern coasts of the North Atlantic. According to AviList v2026, they breed on North Atlantic coasts from Iceland through Norway and France, and Newfoundland (southeastern Canada). They range southward along coasts to the western Mediterranean and northwestern Africa, and to Florida and the northern Gulf of Mexico.
They are found on the ocean at all times of the year, except when they come to land to breed in the summer. Breeding colonies are densely populated and located on sea stacks, steep cliffs, or uninhabited islands. The suitability of these breeding areas is determined by proximity to good foraging grounds, the absence of terrestrial mammalian predators, and the presence of good updrafts for taking off and landing. Nests are placed on cliffs and ledges from just above the high water splash zone to over 200 meters up.
Northern Gannets are gregarious and diurnal, active during the day and foraging mainly in the morning and late afternoon. They nest in dense colonies, often with several nests occupying just 2 to 3 square meters. At sea, they may forage singly, in small groups, or in flocks of over 1,000 birds.
These birds form lifelong monogamous pairs. Males initially compete for breeding spots, but after mating, both sexes aggressively defend their territories. Fights can be fierce, involving locking bills and pushing, and can even result in birds pushing themselves off cliffs to continue fighting in the air. Once a pair bond is established, it is reinforced through displays like "mutual fencing," where they stand facing each other and knock their bills together by shaking their heads side to side. In one study, 94% of males and 88% of females returned to the same nest site the following year.
On land, gannets walk in an ungainly, waddling manner due to their short legs. They must run and hop to gain enough speed for flight. In the air, their flight is strong and direct, with speeds over 60 km/h. They typically fly 10 to 40 meters above the water but can soar higher during migration. They also swim underwater well, using both wings and feet for propulsion.
Northern Gannets are opportunistic generalists that primarily eat schooling fish found at the surface or up to 15 meters deep. Their dominant prey species throughout most of their range are mackerel and herring (Clupea harengus). Other recorded prey include capelin, coalfish, cod, whiting, haddock, sprat, pilchard, garfish, sandlance, smelt, menhaden, flounder, squid, and shrimp. In some colonies, marine-phase salmon (Salmo salar) can make up a significant portion of the diet.
Their primary foraging technique is plunge-diving. They dive from heights of 10 to 40 meters, entering the water at over 100 km/h to depths of 3 to 5 meters. After the initial impact, they can swim to depths of up to 15 meters, using their wings and feet to propel themselves. Most dives are less than 10 meters deep, and they are typically submerged for 5 to 7 seconds, though they can stay underwater for up to 30 seconds. They often feed in association with predatory fish and cetaceans, such as bluefish and dolphins, which drive prey to the surface.
Foraging trips typically range from 60 to 232 km from the colony, though they can travel up to 540 km. These expeditions last 7 to 14 hours, with about half the time spent in flight to the foraging area. When resources are predictable, gannets learn and remember feeding locations, revisiting them over time.
Northern Gannets breed in 32 colonies in the eastern Atlantic and 6 colonies in North America. Females lay a single egg from the end of April through mid-June. The egg is about 105 grams and pale blue-green, becoming thick with a chalky outer layer as incubation progresses. Hatching occurs from early June to early July, with a peak in mid-June.
Young are altricial, meaning they are naked and helpless at hatching, covered only in a thin layer of creamy down. Both parents incubate the egg and brood the chick on the vascularized webbing of their feet, as adults do not develop a brood patch. Females spend more time incubating (74%) than males. The chick grows rapidly, reaching over 4 kg by 10 weeks of age, which is heavier than an adult. Fledging occurs in September, after about 13 weeks of brooding. Fledglings glide off cliff ledges into the sea and swim south towards their wintering range, unable to fly for their first week after leaving the nest.
Northern Gannets are noisy, especially in large groups. Adult vocalizations include loud, metallic, repeated "urrah" calls used during landing, bowing, and threat displays. Alarm calls are staccato "rah rah" versions of the "urrah." They also make hollow groans when taking off or after short hops, and soft "krok krok" sounds while swimming at sea or in low flight over the water. Young birds give cheeping calls when hatching and beg for food from their parents.
The Northern Gannet is listed as Least Concern (LC) in the IUCN Red List, as recorded in AviList v2026. This current assessment reflects a stable global population status. It is important to distinguish this present-day classification from historical population data: the Animal Diversity Web account notes that populations in some portions of the range grew substantially between 1977 and 1999, with an overall yearly increase of 3 to 3.5% during that specific period. These historical growth rates are not a current IUCN trend assessment but rather a record of past recovery, potentially aided by the ban on DDT in North America. Despite the stable global status, gannets continue to face local threats, including entanglement in fishing gear and the accumulation of toxic chemicals like PCBs, mercury, and cadmium in their tissues due to their high trophic level.
Observing Northern Gannets requires patience and distance, as they are sensitive to disturbance, particularly during the breeding season (April to September). On land, look for dense colonies on sea stacks or cliffs. Watch for the "wingflap rotary headshake," a vigorous display where gannets flap their wings, head, and tail to ruffle feathers and shake off debris. During nest exchanges, observe the "skypointing" display, where a relieved parent stands with the bill held vertically, spreads wings upward, and alternates lifting feet while vocalizing an "ooh-ah."
At sea, time your observation for the morning or late afternoon, when foraging activity peaks. Look for flocks of up to 1,000 birds diving in unison or following predatory fish and dolphins. You may also spot them near commercial fishing ships, where they feed on discarded catch. Always maintain a safe distance to avoid stressing the birds or disrupting their breeding and foraging behaviors.
