California Gull

The California gull (Larus californicus) is a medium-sized gull, presenting a smaller stature than the herring gull but larger than the ring-billed gull. It boasts a predominantly white body with a grey back and upper wings, complemented by black primaries edged with white tips. Adults can be distinguished by their yellow legs, brown eyes, and a more rounded head, along with a smaller yellow bill adorned with a distinctive black ring. Immature birds bear a resemblance to their herring gull counterparts but are browner than the immature ring-billed gulls. The species' size ranges from 46 to 55 cm in length, with a wingspan of 122–137 cm, and a body mass between 430 to 1,045 grams.

Identification Tips

When identifying the California gull, look for the combination of a yellow bill with a black ring, yellow legs, and brown eyes. The rounded head shape and the pattern of black and white on the wingtips are also key characteristics to note. In flight, the grey back contrasts with the white body, making it easier to distinguish from similar species.

Habitat

The California gull favors lakes and marshes within the interior western North America as its breeding habitat. These environments range from the Northwest Territories in Canada down to eastern California and Colorado.

Distribution

This gull is not confined to California despite its name; it inhabits the entire Western coast of North America. It is migratory, with many individuals relocating to the Pacific coast during winter months.

Behaviour

California gulls are versatile foragers, feeding in flight or while swimming, walking, or wading. They consume a diet primarily consisting of insects, fish, and the eggs and young of other birds, including ducklings. They are opportunistic and adapt to human presence, scavenging at garbage dumps and begging for food in public spaces. They have also been observed following fishing boats and plows to capitalize on disturbed insects.

Breeding

These gulls nest in colonies, often alongside other bird species. Their nests are shallow depressions on the ground, lined with vegetation and feathers. Typically, the female lays 2 or 3 eggs, with both parents sharing the responsibility of feeding their chicks.

Similar Species

The California gull is similar in appearance to the herring gull but can be differentiated by its smaller size, bill characteristics, and leg color. Immature birds may be confused with immature herring gulls but are distinguishable by their browner plumage.

Diet and Feeding

Apart from their primary diet of insects, fish, and bird eggs, California gulls have been known to consume various vegetables and fruits, with a particular fondness for cherries. This sometimes leads to them being considered crop pests.

Conservation status

The California gull is currently listed as Least Concern by the IUCN. However, in California, its status has fluctuated due to changes in population numbers at breeding colonies, such as the historic colony at Mono Lake. Recent population growth in the southern portion of San Francisco Bay has led to concerns about the impact on other bird species due to predation by large flocks of California gulls. Conservation efforts are in place to manage and reduce the impact of these growing gull populations.