Bird Fact Friday — Western Gulls

Adapted from pages 143-146 of Gulls Simplified:

A large gull with an overall stocky, robust profile, Western Gull is about the same size as Herring and Glaucouswinged Gulls, but adults show a darker, charcoal-gray back. The large head supports a stout, bulbous-tipped bill (smaller and straighter on some birds) and a curious bump or peak on the head (just above the eye, or sometimes above the nape)  that makes the head of Western Gull more convex (rounded) than the overall thinner head and drawn-out face of Herring Gull. The bill of Western typically appears thicker, shorter, and more bulbous tipped compared to Glaucous-winged’s longer, straighter bill, with the exception of some smaller Westerns that have slender bills. Standing birds with neck retracted often appear to slouch. When birds are standing, wing tips extend well beyond the tail and are often elevated, leaving a slight gap between wings and tail.

Western mixes freely with other gulls, especially Glaucous winged, and is often found where humans concentrate. It feeds primarily by scavenging over ocean waters for marine invertebrates. Its large size and bulky profile result in dominance over most gulls in its range. A Western Gull standing atop some elevated point on an ocean pier is a typical and iconic image. In the wave zone, it typically forages alone. 

Western and Ring-billed Gulls, adult. Photo credit: Kevin Karlson.

Two subspecies exist in Western Gull, with subspecies occidentalis occurring in northern California and farther north, and subspecies wymani occurring in southern California and farther south. Southern-breeding birds have a slightly darker back than northern ones, but recognition of this shading difference requires a good amount of study and exposure to both, and birds in the broad overlap zone show intermediate gray shading.

A common and highly coastal West Coast gull, the default dark-backed gull of the West Coast. Breeding range is from the central Washington State coastal zone south to the coastal zone of the central Baja California Peninsula, Mexico. Winter range includes the breeding range and smaller areas north to the Canadian border and south to the southern tip of Baja, as well as the northern Gulf of California.

In winter on California beaches, Western is typically the most numerous gull species. If you are standing on a California beach and you are looking at a large, dark-backed gull, STOP; you are most likely looking at an adult or 3rd winter Western Gull. Western Gull also frequents landfills, harbors, lakes, and rivers. No other large, charcoal gray–backed gull typically occurs within its range along the Pacific coast.

Gulls Simplified
A Comparative Approach to Identification
By Pete Dunne and Kevin Karlson

This unique photographic field guide to North America’s gulls provides a comparative approach to identification that concentrates on the size, structure, and basic plumage features of gulls—gone are the often-confusing array of plumage details found in traditional guides.

Featuring hundreds of color photos throughout, Gulls Simplified illustrates the variations of gull plumages for a variety of ages, giving readers strong visual reference points for each species. Extensive captions accompany the photos, which include comparative photo arrays, digitized photo arrays for each age group, and numerous images of each species—a wealth of visual information at your fingertips. This one-of-a-kind guide includes detailed species accounts and a distribution map for each gull.

An essential field companion for North American birders, Gulls Simplified reduces the confusion commonly associated with gull identification, offering a more user-friendly way of observing these marvelous birds.

  • Provides a simpler approach to gull identification
  • Features a wealth of color photos for easy comparison among species
  • Includes detailed captions that explain identification criteria and aging, with direct visual reinforcement above the captions
  • Combines plumage details with a focus on size, body shape, and structural features for easy identification in the field
  • Highlights important field marks and physical features for each gull


This post is part of a series, explore additional posts here<< Bird Fact Friday — the Great Black-Backed GullBird Fact Friday — Mew Gull >>