The western gull (Larus occidentalis ) is a large white-headed gull that lives on the west coast of North America. It was previously considered conspecific with the yellow-footed gull (Larus livens ) of the Gulf of California. The western gull ranges from British Columbia, Canada to Baja California, Mexico.
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DiurnalDiurnal animals are active during the daytime, with a period of sleeping or other inactivity at night. The timing of activity by an animal depends ...
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CarnivoreA carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of a...
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ScavengerScavengers are animals that consume dead organisms that have died from causes other than predation or have been killed by other predators. While sc...
A piscivore is a carnivorous animal that eats primarily fish. Piscivorous is equivalent to the Greek-derived word ichthyophagous. Fish were the die...
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SemiaquaticSemiaquatic animals are those that are primarily or partly terrestrial but that spend a large amount of time swimming or otherwise occupied in wate...
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SeabirdSeabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, b...
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PrecocialPrecocial species are those in which the young are relatively mature and mobile from the moment of birth or hatching. Precocial species are normall...
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TerrestrialTerrestrial animals are animals that live predominantly or entirely on land (e.g., cats, ants, snails), as compared with aquatic animals, which liv...
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CongregatoryCongregatory animals tend to gather in large numbers in specific areas as breeding colonies, for feeding, or for resting.
Oviparous animals are female animals that lay their eggs, with little or no other embryonic development within the mother. This is the reproductive...
Soaring birds can maintain flight without wing flapping, using rising air currents. Many gliding birds are able to "lock" their extended wings by m...
Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, b...
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MonogamyMonogamy is a form of relationship in which both the male and the female has only one partner. This pair may cohabitate in an area or territory for...
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Partial MigrantPartial migration is when within a migratory species or even within a single population, some individuals migrate while others do not.
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MigratingAnimal migration is the relatively long-distance movement of individual animals, usually on a seasonal basis. It is the most common form of migrati...
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starts withThe Western gull is a large seabird that lives on the west coast of North America. It has a white head and body, gray wings and yellow bill. In Washington state, the Western gull hybridizes frequently with the Glaucous-winged gull, and may closely resemble a Thayer's gull. The hybrids have a flatter and larger head and a thicker bill with a pronounced angle on the lower part of the bill, which distinguishes it from the smaller Thayer's gull.
The range of Western gulls extends from British Columbia, Canada to Baja California, Mexico. These birds are found at sea, on offshore islands and rocks along the coast, on islands inside estuaries, and on beaches.
Western gulls are almost exclusively marine birds and rarely venture far from the ocean. They are social but territorial; in the colonies pairs aggressively defend territories whose borders may shift slightly from year to year, but are maintained for the life of the male. Western gulls are active during the day. They are unable to dive and feed exclusively on the surface of the water. Western gulls are noisy birds and have a loud “keow” call or a rapid “quock-kuk-kuk-kuk”.
Western gulls are carnivores and scavengers. At sea, they eat fish and invertebrates like krill, squid, and jellyfish. On land, they feed on the seal and sea lion carcasses and roadkill, as well as cockles, starfish, limpets, and snails in the intertidal zone. They also feed on human food refuse, and take food given to them, or stolen from people at marinas, beaches, and parks. Western gulls may also eat the young of other birds, especially ducklings, and even the adults of some smaller bird species.
Western gulls are monogamous and mate for life. They nest in colonies on offshore islands or rocks along the coast. A nest of vegetation is constructed on the ground inside the parent's territory. The female lays 3 eggs and both parents incubate them for a month. The chicks, once hatched, are able to leave the nest a few days after hatching but remain inside the territory until they have fledged. They begin to fly at 6-7 weeks of age and become independent when they are 10 weeks old. Young Western gulls reach reproductive maturity and are ready to breed for the first time at 4 years of age.
Western gulls are currently not considered threatened. However, they have a restricted range. Their numbers were greatly reduced in the 19th century by the egg collection for the growing city of San Francisco. Western gull colonies also suffered from disturbance where they were turned into lighthouse stations, or, in the case of Alcatraz, a prison. These birds are very aggressive when defending their territories and consequently were persecuted by some as a menace. They are currently vulnerable to climatic events like oil spills and El Niño (temperature fluctuation of the surface water layer in the equatorial part of the Pacific Ocean, which has a noticeable effect on the climate).
According to the IUCN Red List, the total population size of Western gulls is 115,500-118,500 individuals. Currently, this species is classified as Least Concern (LC) on the IUCN Red List and its numbers today are increasing.
Social animals are those animals that interact highly with other animals, usually of their own species (conspecifics), to the point of having a rec...