Named for its gray wings (the greek word "glaukos" means blue-gray), this species is the most common large (average body length of 26 inches) gull around Puget Sound.
Identifying gulls is not an easy task. This species can be confused with a similar-sized gull with a darker back called a western gull. In addition, these two species interbreed, resulting in a hybrid that is not easily distinguished form the lighter glaucous-winged gull. They also take four years to mature, and each year, they show a different range of feather colors. Even the bill color varies with age.
The glaucous-winged gull is found from Baja California to Alaska. While they are mainly a coastal species, they have expanded their range to inland areas of the Pacific Northwest in the past 50 years.
Members of this species, like other gulls, nest in colonial groups. Nesting locations include isolated cliffs, small islands and the tops of large warehouses or apartment buildings near water. Adults usually return to the same nesting location and partner each year.
The nests are made of seaweed and grass. The eggs are laid in spring and take about 29 days to hatch. The young stock close to the nest while being fed by the parent for 35 to 50 days. The young trigger the regurgitation of food by pecking at the red spot on the parent's bill.
They feed on a variety of food, including sea starts, moon snails, crabs, clams, mussels, small fish and human garbage. They also spend lots of time stealing food from diving ducks and other gulls. They breach the shelled defense of clams and snails by dropping them from a height of 15 to 30 feet into rocks or gravel. They swallow small sea stars whole.
Source: David W. Jamison is a Boston Harbor resident and marine biologist