Introduction

Adult Glaucous-winged Gull landing at its nest site.

Figure 1. Breeding and nonbreeding (generally winter) range of the Glaucous-winged Gull.

Adult Glaucous-winged Gull, British Columbia. Non-breeding plumage (Definitive Basic).

The Glaucous-winged Gull is an abundant resident along the northwestern coast of North America, where its bold nature and omnivorous food habits make it a familiar sight in coastal cities and towns. Although generally an inshore species, it does venture away from the coast where it is often seen around fishing vessels at sea. This species has steadily increased in numbers in the last few decades, particularly around urban centers, owing mainly to environmental changes and to the availability of garbage and fish offal.

This gull generally nests at high densities in large or small colonies on offshore islands, although it has recently begun nesting on roofs of waterfront buildings. Individuals form apparently monogamous pairs, which usually stay together for several years; small nesting territories within the colony are defended vigorously and noisily against neighboring pairs. Each pair can produce up to three young in a season. This species hybridizes with Western Gulls (L. occidentalis) in the southern part of its breeding range, in northern Oregon and Washington, and with Herring Gulls (L. argentatus) and Glaucous Gulls (L. hyperboreus) in Alaska. The resulting hybrids are often difficult to identify.

The first significant study of this species was by Zella M. Schultz who examined the growth and plumage of these birds (Schultz 1951, 1952). A semi-fictional account of her work with Glaucous-winged Gulls on Protection Island, WA, was published posthumously (Schultz 1986). Elden James-Veitch and Ernest S. Booth (1954) examined behavior and life history factors and provided measurement data for eggs, chick growth, and adult males and females (James-Veitch and Booth 1954). Kees Vermeer characterized the breeding ecology and provided extensive tabulated life history data for this species (Vermeer 1963); he and his colleagues later expanded on this work (Vermeer 1982, Vermeer and Devito 1987, 1989, Vermeer and Irons 1991, Vermeer et al. 1988, 1989a, 1989b, 1989c, 1991, 1992a, 1992b, 1994). Agonistic behavior during the breeding season was detailed in a series of observational and experimental studies by John F. Stout and his students (Stout et al. 1969, Stout and Brass 1969, Stout 1975, Galusha and Stout 1977, Hayward et al. 1977, Amlaner 1977a, 1977b, Amlaner and Stout 1978, Schwab and Stout 1991). Nicholas A. M. Verbeek examined a variety of factors related to reproductive behavior and ecology (Verbeek 1979, 1982, 1984, 1986, 1988, 1996, Verbeek and Morgan 1978, 1980, Verbeek and Richardson 1982). Charles J. Amlaner, Nigel J. Ball and their students examined sleep behavior, including unihemispheric sleep (Ball et al. 1985, 1986, 1988). Walter V. Reid evaluated reproductive and population biology (Reid 1987a, 1987b, 1988a, 1988b, 1988c). Joseph G. Galusha and his students examined aspects of behavior on nesting territories (Van Scheik 1980, Opp 1983, Nestler 1985, Schmidt 1986, Galusha and Carter 1987, Kennett 1987, McKee 1987, Pearson 1992, Durr 1993, Murdoch 1993, Forsyth 1994, Olango 1998, Edwards 2001, Colburn 2004). Samuel M. Patten examined interbreeding between this species and Herring Gulls (Patten 1974, 1980, Patten and Weisbrod 1974), and Douglas A. Bell provided genetic, behavioral, and population analyses related to the hybridization of this species with Western Gulls (Bell 1992, 1996, 1997). Shandelle M. Henson, James L. Hayward, and their students developed mathematical models that describe and predict the dynamics of habitat occupancy and behavior (Henson et al. 2004, 2006, Damania et al. 2005, Phillips et al. 2005).