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Herring Gull Class: Aves

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Herring Gull Class: Aves Larus argentatus Herring Gull Class: Aves. Order: Chardiiformes . Family: Laridae. Other names: Seagull Physical Description: The herring gull is a large common gull with widespread distribution throughout the Northern hemisphere. As a result it can have many variations on its size, shape and plumage. There is more about the bird’s plumage under “Additional information” section. This species, like other large gulls, takes four years to obtain adult plumage, so young birds look quite different from adults. Juveniles are brown while adults are white with light gray backs and wings. Adults have black wing tips. The bill is yellow with a red spot on the lower mandible. They are large gulls with an overall length of 25”, a wing spread of 4 ½ feet and weigh 2.5 pounds. Diet in the Wild: Herring gulls are omnivores, feeding on both plants and small animals such as fish, crustaceans and other animals. They are highly adaptable and will adjust their diet to the type of habitat they live in. Birds that live on rocky coasts prey on sea urchins, crabs, mussels and crayfish, on mudflats they hunt worms, clams and mussels while at sea the gulls follow fishing boats and catch small fish and other animals disturb by the boats wake. Newly plowed fields expose worms and other small invertebrates that gulls may flock to. Herring gulls are also opportunistic scavengers and frequent dumps and recreational areas to seek out scraps left behind. The opportunism of gulls extends to raiding nests of other seabirds, and one or two males per large breeding colony may even specialize in cannibalizing chicks of others in the colony. Diet at the Zoo: Fish, bird of prey diet, insects. Range and Habitat: x Herring gulls are found around the world with several subspecies whose ranges include most of North America, Siberia and Europe. x Herring Gulls' scavenging habits take them to open water, intertidal pools and shallows, mud flats, landfills, newly plowed fields, picnic grounds, and fish-processing plants. They roost and loaf, often in large mixed species groups, in open areas with good visibility for spotting predators, including agricultural and athletic fields, beaches, parking lots, airport runways, and garbage dumps. They breed near lakes in northern forests across Canada to Alaska and in some coastal areas. Life Span: Up to 15 years in captivity Perils in the wild: Birds of prey such as peregrine falcons are regular predators of many species of water birds including sandpipers, shorebirds, terns and gulls. Young chicks may be eaten by scavenging gulls in the colony. 07/2013 Physical Adaptations: x The wings of herring gulls are and amazing compromise of soaring, speed and agility, specializing in no one area but having the potential to be good at all. Their fight style works well for the coastal habitats it inhabits. Often circling over head and then diving quickly when food is spotted. x Herring gulls feet are webbed so they can swim while floating on the water surface, but not as agile as a diving duck or penguin. x Their elongated beak is well adapted for x Herring Gulls prefer drinking freshwater, but they'll drink seawater when they must. Special glands located over the eyes allow them to excrete the salt that would otherwise dehydrate most animals, including us. The salty excretion can be seen dripping out of their nostrils and off the ends of their bills. Behavioral Adaptations: x Herring Gulls patrol shorelines and open ocean in widely scattered groups, soaring raptor-like and spiraling down to pick scraps off the surface. Individuals plunge-dive from near the surface and dip while paddling to take shallow prey. Rallying around fishing boats or refuse dumps, they are raucous and competitive, threatening and stealing from other birds. They'll prowl tide flats seeking out invertebrates, gobbling small items whole, picking apart larger prey, and dropping shellfish onto rocks to break them open. Tighter groups follow foraging whales, groups of dolphins, or schools of large fish in open water, hovering to nab small prey driven to the surface. x Herring gulls live in colonies and can be seen flying in groups looking for food, “loafing” while waiting for feeding opportunities. Loafing is a term used to describe the leisure period of napping and not doing much of anything! Opportunistic feeders such as gulls and birds of prey may spend a considerable amount of time loafing. x Young Herring Gulls appear to be more migratory than adults. In some areas, such as the Great Lakes, most adults remain near their breeding grounds, but the non-breeders move father south in the fall. x Even though they live in flocks or colonies, herring gulls mate for life and will return to the same nest sites or area each year. Reproduction and Development: x Herring Gull pairs pick nesting sites together in the soft soil, sand, or short vegetation of their territory. To protect the nest from prevailing winds and hide it from predators, it is usually placed next to a rock, log, or bush. This also hides it from the nearest neighbors. Crevices may be used as nest sites in rocky areas. x Several days before egg-laying, pairs hollow out up to four depressions 10–15 inches across with central depressions 4–8 inches wide and about the depth of an egg. They line the scrapes with vegetation, feathers, plastic, rope, or other materials. The pair chooses the final nest from these alternates. After the female lays her eggs, the pair continues to add vegetation to this nest throughout the month long incubation. Sand nests are sometimes left unlined or only sparsely lined. x They lay 1-3 eggs that are about 3” long and 2” wide. Incubation is 31 days until hatching. x The young are cared for in the nest for about 45-50 days. They are demanding feeders and can consume as much as a half a pound of food daily when they are large. This requires both parents to forage for food 24 hours a day to provide enough food for the young and themselves. 07/2013 x Sibling rivalry is a problem in the bird world, too. The third chick in a herring gull clutch can have it especially tough. While the first two chicks hatch the same day, the third is born a day or two later, weighs less, gets less food, and grows more slowly. Additional Information: x Variety of plumages: Herring gulls display many variations in plumage over a life time. The birds have a long period of immaturity where they go through successive molts until they reach maturity at about four years old. As adults the birds display a breeding and non-breeding plumage as shown below. Immature herring gull Adult herring gull in spring plumage The herring gull’s plumage changes over several years from a brown marked immature to a white and grey adult. Adult herring gull in winter plumage Conservation Status: (IUCN Status) L/C Least Concern, population increasing; IUCN 2013 Conservation Efforts: x Herring gulls benefit from protection of wetland habitat that is home to a tremendous diversity of wildlife. 07/2013 Glossary: List of definitions of the most important recurrent technical terms used in the text. Aves- The class of vertebrates that is represented by the birds. Approximately 9000-10,000 species identified. Chardiiformes- The order of birds that includes shorebirds, gulls, terns, skuas and auks. Laridae- The family of gulls and terns. Plumage- The feathers that cover a birds body parts. Feather types include contour, down, flight, sensory and display feathers. In many species the external characteristics of feathers such as color or external displays, may help to identify the species, sex or age of the individual bird. Omnivore- And organism that feeds on both plants and animals, Sources: x Cincinnati Zoo & Botanical Gardens x Sibley, D.A. 2000. The Sibley Guide to Birds x http://www.allaboutbirds.org/guide/herring_gull/lifehistory x Hickman, C.P. Roberts, L.S. 1994. Biology of Animals 07/2013 .
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