The Glaucous-winged Gull (Larus glaucescens) is a seabird living along the coast of the northeast Pacific Ocean. It breeds in colonies and occasionally as individual pairs, mainly on offshore islands from northwest Washington to the Bering Sea.
Winter finds the Glaucous-winged Gull occupying its breeding range and straggling as far as south Baja California and to Japan. In spring, tens of thousands of Glaucous-winged Gulls gather to feast on adult herring and their eggs, and during summer, they prey on juvenile herring, among other things.
The gull’s name comes from glaucescens, New Latin for “glaucous” from the Ancient Greek word glaukos, denoting the grey colour of its wings. The gull is rarely found far from the ocean.
It feeds by scavenging for dead or weak animals, fish, mussels and scraps. In urban areas, it is known for its tendency to accept food from people and peck open unprotected garbage bags in search of edibles.
Breeding
Life in a gull colony is loud and raucous. Each gull returns to the same nesting territory they occupied the previous year to build a nest and raise their young. Territories provide only a few square meters of elbowroom and the hubbub involved in securing it shows the seriousness of its defence. Volleys of shrieking calls, bluff charges and the occasional scuffle break out as mates vie for their turf.
An invisible territory line is vigorously defended against neighbouring trespassers for much of the summer. Nests are built in the territory from grasses and mosses, occasional flotsam, feathers, and other items that can be shaped into the nest.
The typical clutch of three eggs is laid in June and incubated for 27 days. Most eggs hatch in July, and the young gulls depend entirely on their parents to bring food to the territory. At this time of year, the colony is alive with the begging calls of the young chicks and territorial calls of the adults.
Adult gulls roam far in search of food that includes mostly refuse, fish, and marine invertebrates. The chicks are fed chiefly a diet of juvenile herring and blennies, salmon, and sculpins.
The winds that sweep over the gull colonies provide a lift to adults who call to their chicks below, trying to get airborne. Young gulls eventually are capable of flight by mid-July and soon drift away from their natal colonies. They return as breeding age adults when they are between 3 and 5 years of age.
References:
Butler, R. W., N. A. M. Verbeek and R. G. Foottit. 1980. Mortality and dispersal of the Glaucous-winged Gulls of southern British Columbia. Canadian Field-Naturalist 94:315-320.
Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 174, 219. ISBN 978-1-4081-2501-4.
Sullivan, T. M., S. L. Hazlitt and M. J. F. Lemon. 2002. Population trends in nesting Glaucous-winged Gulls, Larus glaucescens, in the southern Strait of Georgia, British Columbia. Canadian Field-Naturalist 116: 603-606.
Verbeek, N. A. M. 1986. Aspects of the breeding biology of an expanded population of Glaucous-winged Gulls in British Columbia. Journal of Field Ornithology 57:22-33.
Vermeer, K. 1963. The breeding ecology of the Glaucous-winged Gull (Larus glaucescens) on Mandarte island, British Columbia. British Columbia Provincial Museum Occasional Paper Number 13, 104 pp.