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The Ivory Bill·Birds·Seabirds

Glaucous-winged Gull, Larus glaucescens

Solitary glaucous-winged gull near the water.

Glaucous-winged Gulls are large seabirds that breed in coastal habitats and offshore islands in the northern Pacific, including regions of Alaska, British Columbia, and northern Washington, from May to July.

Glaucous-winged Gulls are commonly found in rocky cliffs, coastal islands, and estuarine areas, where fish, marine invertebrates, and other prey are abundant during the breeding season. These habitats often have rich intertidal zones and access to both marine and freshwater resources.

They forage in coastal waters, rocky shores, and mudflats for fish, crabs, sea urchins, and mollusks. They may also feed on carrion, small mammals, birds, and eggs. Urban environments provide additional food sources, such as refuse and scraps.

Glaucous-winged Gulls have robust foraging strategies, including diving, surface dipping, and scavenging. Their powerful beaks enable them to open hard-shelled prey like mollusks and crabs. They are also known to follow fishing boats and feed on discarded bycatch.

Courtship involves elaborate displays where males offer food to females and engage in synchronized flights and vocalizations. Ground displays include head-tossing, mutual preening, and the “long call” display, where they stretch their necks upward and call loudly.

Nest building is carried out by both parents, who construct a large, bulky nest from grass, seaweed, feathers, and other available materials. Nests are typically situated on cliffs, rocky outcrops, or man-made structures, often in colonies with other seabirds.

Egg laying occurs from late May to early June, with the female usually laying two to three eggs. Both parents share incubation duties, which last about 27 to 30 days. Upon hatching, the chicks are semi-precocial and require significant parental care. Initial diets for chicks consist of regurgitated fish and marine invertebrates provided by the parents.

Chicks learn to forage by observing and following their parents. They face vulnerabilities such as predation by larger birds, mammals, and exposure to harsh weather conditions. Parental care includes leading chicks to food sources, protecting them from predators, and teaching them to handle different prey.

Chick fledging occurs about 40 to 50 days after hatching, with continued guidance from adults as the chicks develop their foraging skills. Their diet broadens to include a wider range of fish, invertebrates, and other available food sources as they grow.

Glaucous-winged Gulls are partial migrants, with northern populations moving southward to winter along the coasts of the Pacific Northwest, California, and Baja California. Migration occurs from late August to October, following coastal routes.

Wintering habitats include coastal bays, estuaries, and offshore waters, where they forage for fish, crustaceans, and marine invertebrates. Their diet during winter is diverse, adapting to the availability of food in these coastal and marine environments.

Glaucous-winged Gulls typically leave their wintering grounds in late February to early March, returning north to their breeding areas as temperatures rise and food becomes more abundant, ensuring a rich supply of prey for the breeding season.