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Great Black-backed Gull

Larus marinus ORDER: CHARADRIIFORMES FAMILY: LARIDAE

IUCN Conservation Status: Least Concern

The king of the Atlantic waterfront, the Great Black-backed Gull is the largest gull in the world, with a powerful build and a domineering attitude. They harry other birds to steal their food and even hunt adult birds such as grebes and puffins. Adults are handsome with broad black wings, gleaming white head, and big yellow bill. North American populations were once severely threatened by the feather trade, but numbers rebounded in the twentieth century and they are now a common East Coast sight.

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At a GlanceHelp

Measurements
Both Sexes
Length
28–31.1 in
71–79 cm
Wingspan
57.5–63 in
146–160 cm
Weight
45.9–70.5 oz
1300–2000 g
Other Names
  • Goéland marin (French)
  • Gavion (Spanish)

Cool Facts

  • This is the largest gull in the world. Its broad wings and powerful appearance give it a regal look that have impressed naturalists for years. In the words of one early observer: “It surely seemed to be a king among the gulls, a merciless tyrant over its fellows, the largest and strongest of its tribe. No weaker gull dared to intrude upon its feudal domain.”
  • The Great Black-backed Gull is one of many bird species whose feathers were used for fashionable clothing in the 1800s. After the demise of the feather trade in the early 1900s, Great Black-backed Gull populations increased and spread farther south. Garbage dumps and other sources of human refuse have contributed to their range expansion.
  • Young Great Black-backed Gulls stay in the nesting territory until they learn to fly at about 7 weeks old. They return to the nesting area to rest and get fed for another few weeks. Some young may remain with their parents for months after leaving the breeding colony, but most join up with other immature gulls in places where food is easy to find.
  • During winter, large numbers of young Great Black-backed Gulls eat fish driven to the surface by humpback whales.
  • The oldest Great Black-backed Gull on record was at least 25 years, 5 months old.

Habitat


Shore-line

Great Black-backed Gulls forage widely over the ocean, along shorelines, and at landfills and fishing docks. They rest or “loaf” in open areas such as parking lots, fields, runways, and piers. They breed in isolated places safe from terrestrial predators, such as small islands, rocky islets, saltmarshes, and barrier beaches. They nest in relatively high, open habitat close to the water, with some vegetation for cover. During the winter Great Black-backed Gulls move more widely along the Atlantic coast and may travel inland along major rivers.

Food


Omnivore

Great Black-backed Gulls hunt mussels, crabs, sea urchins, other marine invertebrates, fish and birds. They also scavenge dead fish, carrion, and trash, and steal food from other animals (including diving ducks, terns, puffins, murres, shorebirds, eagles, and sharks). Along rocky shores, Great Black-backed Gulls forage for invertebrates in shallow water. On mudflats they follow the retreating tide to capture worms and small bivalves. At sea they congregate around upwellings with concentrated prey or follow fishing boats. They also forage at garbage dumps, more so during the winter than during the breeding season. Great Black-backed Gulls eat eggs, chicks, and adults of other birds, including Atlantic Puffins, Common Murres, Herring Gulls, Common Terns, Roseate Terns, Manx Shearwaters, Horned Grebes, and migrant songbirds.

Nesting

Nesting Facts
Clutch Size
2–3 eggs
Number of Broods
1 broods
Egg Length
2.8–3.3 in
7.1–8.5 cm
Egg Width
2–2.3 in
5.1–5.8 cm
Incubation Period
30–32 days
Nestling Period
1 days
Egg Description
Pale yellowish, greenish, or brownish, with speckles of dark brown or olive.
Condition at Hatching
Fairly active, with open eyes, and covered in thick gray down with black spots; ready to leave nest within 24 hours.
Nest Description

The male and the female both dig several scrapes, filling them with vegetation, feathers, rope, plastic, and other materials. The female chooses one of these sites for laying her eggs. The nest is 8–20 inches wide, while the inner cup is 5–13 inches across and 2-4 inches deep.

Nest Placement

Ground

Great Black-backed Gulls nest on rocky outcrops, grassy knolls, barrier island dunes, and other sites above the reach of the tide. Nests are usually next to large objects such as logs, bushes, or rocks, which provide a windbreak and a visual screen from the neighbors. Each pair starts several nests, and the final site is determined by where the female lays her eggs. The pair reuses the same site, but not the nest itself, in subsequent years.

Behavior


Ground Forager

Great Black-backed Gulls nest on their own or in loose colonies, sometimes with other gulls, terns, skimmers, auks, and eiders, and rarely with cormorants and gannets. The male establishes a small breeding territory, 10 to 20 feet in diameter, and the pair defends it against other gulls. Great Black-backed Gulls are monogamous and return to the same territory year after year. When pairing, a male displays and calls to attract a female, leaning forward with his head bent toward the ground and mewing; or flying slowly with exaggerated wingbeats. The female may join him. Courting males sometimes regurgitate food for females. Aggressive individuals crouch low and jab their bill at an opponent, or pull at vegetation. They also stand, lean far forward, then throw back their head and give a long series of cries. After chicks hatch the parents become especially aggressive. When terrestrial predators approach, the gulls dive and strike with their feet or wings, or rarely with their bills. Lost chicks that stray onto an unfamiliar territory may find themselves seized by the head and shaken, or even eaten. Chicks leave the nest within 24 hours but stay in the nesting territory for 40 days. They begin to fly at 45 days but return to the territory for feedings from their parents for another 3-4 weeks. Egg predators include various gull species, ravens, crows, raccoons, and rats. Bald Eagles, Common Ravens, dogs, cats, and other gulls sometimes prey on the chicks.

Conservation

status via IUCN

Least Concern

Great Black-backed Gulls are numerous on the East Coast and are found in the U.S. and Canada. The North American Breeding Bird Survey found that between 1966 and 2010 there was an increase in populations in some of the mid-Atlantic states, but overall populations appear to have declined with significant losses in Maine and Nova Scotia. Nineteenth-century feather hunters and egg collectors nearly drove the North American population of Great Black-backed Gulls to extinction. Thanks to legal protection, the population recovered during the twentieth century and perhaps exceeded its historical size by the 1960s. Taking advantage of landfills, fishing discards, and other human-made food sources, the gulls continued to increase in numbers as they expanded south into Maryland, Virginia, and North Carolina. They have displaced Herring Gulls from some breeding habitats in New England. Management officials control the breeding Great Black-backed Gull populations on some islands to give terns, puffins, and other gull species a chance to nest.

Credits

Range Map Help

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Migration

Resident to medium-distance migrant. Populations from Nova Scotia and Massachusetts remain around breeding colonies throughout the year, while birds from Maine, the Gulf of St. Lawrence, Newfoundland, and the mid-Atlantic migrate south along the coast or to the Great Lakes region.

Find This Bird

Along much of the East Coast of North America, you should be able to find Great Black-backed Gulls at beaches or fishing piers. They’ll be the largest gulls around—look for the huge size, big head and bill, and very broad wings. Adults have a very dark back and wings—very nearly black—making the identification fairly easy. Immatures are less obviously marked, but their large, bulky size and shape is the same as adults.

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