American Herring Gull

Appearance

It is a heavily-built large gull with a long powerful bill, full chest and sloping forehead. Males are 60–66 cm long and weigh 1,050–1,650 g. Females are 53–62 cm long and weigh 600–900 g. The wingspan is 120 to 155 cm. Among standard measurements, the wing chord is 41.2 to 46.8 cm, the bill is 4.4 to 6.2 cm and the tarsus is 5.5 to 7.6 cm.

Breeding adults have a white head, rump, tail, and underparts and a pale gray back and upperwings. The wingtips are black with white spots known as "mirrors" and the rear edge of the wing is white. The underwing is grayish with dark tips to the outer primary feathers. The legs and feet are normally pink but can have a bluish tinge, or occasionally be yellow. The bill is yellow with a red spot on the lower mandible. The eye is bright, pale to medium yellow, with a bare yellow or orange ring around it. In winter, the head and neck are streaked with brown.

Young birds take four years to reach fully adult plumage. During this time they go through several plumage stages and can be very variable in appearance. First-winter birds are gray-brown with a dark tail, a brown rump with dark bars, dark outer primaries and pale inner primaries, dark eyes, and a dark bill, which usually develops a paler base through the winter. The head is often paler than the body. Second-winter birds typically have a pale eye, pale bill with black tip, pale head and begin to show gray feathers on the back. Third-winter birds are closer to adults but still have some black on the bill and brown on the body and wings and have a black band on the tail.* Lonergan, Pat and Killian Mullarney Identification of American Herring Gull in a western European context "Dutch Birding" 26: 1-35

Naming

Adult European Herring Gulls are very similar to American Herring Gulls but those of the subspecies "L. a. argenteus" are smaller than many American birds while those of the northern subspecies "L. a. argentatus" are typically darker gray above. European birds lack the long gray tongues on the 6th, 7th, and 8th primaries and solid black markings on the 5th and 6th primaries that are shown by American Herring Gulls. First-winter European birds have more checkered upperparts, more streaked underparts, and a paler rump and base to the tail.

Distribution

The breeding range extends across the northern part of North America from central and southern Alaska to the Great Lakes and north-east coast of the USA south to North Carolina. It breeds over most of Canada apart from the southwest and Arctic regions.

Birds are present all year in southern Alaska, the Great Lakes and north-east USA but most birds winter to the south of the breeding range as far as Mexico with small numbers reaching Hawaii, Central America and the West Indies. Vagrants have reached Colombia and Venezuela and there is a report from Ecuador and another from Peru. The first European record was of a bird ringed in New Brunswick which was caught on a boat in Spanish waters in 1937 and there are have a number of additional records from Western Europe since 1990. The first British record was in 1994 in Cheshire.

It usually nests in colonies near water on coasts, islands, and cliffs. It also nests on rooftops in some cities. It feeds at sea and on beaches, mudflats, lakes, rivers, fields, and refuse dumps. It roosts in open areas close to feeding sites.

Status

The species became quite rare during the 19th century when it was hunted for its eggs and feathers. From the 1930s to 1960s, it increased rapidly due to protection from hunting, increased waste from fisheries to feed on and less competition for small fish and invertebrates as humans reduced the populations of large fish, whales, and pinnipeds. Numbers leveled off during the 1970s and 80s and may now be declining in some areas.

Habitat

The breeding range extends across the northern part of North America from central and southern Alaska to the Great Lakes and north-east coast of the USA south to North Carolina. It breeds over most of Canada apart from the southwest and Arctic regions.

Birds are present all year in southern Alaska, the Great Lakes and north-east USA but most birds winter to the south of the breeding range as far as Mexico with small numbers reaching Hawaii, Central America and the West Indies. Vagrants have reached Colombia and Venezuela and there is a report from Ecuador and another from Peru. The first European record was of a bird ringed in New Brunswick which was caught on a boat in Spanish waters in 1937 and there are have a number of additional records from Western Europe since 1990. The first British record was in 1994 in Cheshire.

It usually nests in colonies near water on coasts, islands, and cliffs. It also nests on rooftops in some cities. It feeds at sea and on beaches, mudflats, lakes, rivers, fields, and refuse dumps. It roosts in open areas close to feeding sites.

Reproduction

Pairs form in March or April. The nest is a scrape on the ground lined with vegetation such as grass, seaweed, and feathers. Usually three eggs are laid over a four to six day period. They are 72 mm long and are variable in color with brown markings on a pale blue, olive or cinnamon background. The eggs are incubated for 30–32 days beginning when the second egg is laid. The young birds fledge after 6–7 weeks and are fed in the nest area for several more weeks. They continue to be cared for by the parents until they are about 6 months old. Both parents are involved in building the nest, incubating the eggs and feeding the young.
It has been observed that some pairs cement a close bond, staying in watchful proximity of each other year round; Other gulls display more independence, but may take the same mate each spring.

Food

It has a varied diet including marine invertebrates such as mussels, crabs, sea urchins, and squid, fish such as capelin, alewife, smelt, insects, and other birds including their chicks and eggs. It often feeds on carrion and human refuse. Food is plucked from the surface of the shore or sea or is caught by dipping underwater or by shallow plunge-diving.