Western Gull

The Western Gull, Larus occidentalis, is a robust, white-headed gull that graces the western coastline of North America. This bird is notable for its substantial size, with a length ranging from 55 to 68 cm, a wingspan of 130 to 144 cm, and a weight between 800 to 1,400 grams. Its plumage is a study in contrast, with a pristine white head and body set against a dark grey mantle. The Western Gull's bill is a striking yellow, tipped with a red spot, and its legs are pink. Eye color varies from pale yellow in the south to darker hues in the north.

Identification Tips

To identify the Western Gull, look for its large, bulbous-tipped yellow bill marked with a red spot near the end. The bird's dark grey mantle and white head, which remains largely unmarked throughout the year, are also distinctive. Juveniles take about four years to acquire the full adult plumage, transitioning through various stages marked by mottled brown and grey feathers.

Habitat

The Western Gull is a bird of the marine environment, favoring offshore islands and rocks for nesting. It is also found on islands within estuaries and occasionally on mainland coastal areas.

Distribution

This gull is predominantly found along the Pacific coast, with a range extending from British Columbia, Canada, to Baja California, Mexico. It is a year-round resident in much of its range but migrates to spend the nonbreeding season in areas such as northern Washington and Baja California Sur.

Behaviour

The Western Gull is a coastal species, rarely straying more than 100 miles inland and preferring the immediate vicinity of the ocean. It exhibits strong territorial behavior, with long-term pairs defending their nesting areas with vigor. These territories may shift slightly but are generally maintained for the life of the male.

Song & Calls

The call of the Western Gull is a bright, piercing sound that is often repeated. It serves as a means of communication between individuals, particularly in the dense colonies where these birds nest.

Breeding

Nesting within their territories, Western Gulls construct nests of vegetation and lay a clutch of three eggs. These eggs are incubated for about a month. Chick mortality is high, and typically only one chick survives to fledge. In some cases, abandoned chicks may be adopted by other gulls.

Similar Species

The Western Gull can be confused with the closely related Glaucous-winged Gull, especially in the northern parts of its range where the two species hybridize. The hybrids, known as "Olympic Gulls," may exhibit features of both parent species.

Diet and Feeding

Western Gulls are opportunistic feeders, taking a variety of prey from both marine and terrestrial environments. At sea, they feed on fish, krill, squid, and jellyfish, while on land they consume carrion, intertidal invertebrates, and human refuse. They are also known to be predatory, occasionally preying on the young of other birds and even adult birds of smaller species.

Conservation status

The IUCN lists the Western Gull as Least Concern. However, the species has faced challenges in the past, including egg harvesting and habitat disturbance. Today, they are vulnerable to climatic events like El Niño and oil spills, but conservation efforts have allowed them to reclaim parts of their range.