Bird Fact Friday: A Basic Approach to Gull ID

Adapted from page 23-24 of Gulls Simplified:

For all their inherent challenges, gulls do present students of birds with ID advantages.

Most gulls are readily distinguishable as gulls, members of the family Laridae, simplifying the identification process by eliminating the need to initially assign an unidentified bird to a broader grouping or family.

Gulls are mostly large enough to note key differentiating traits relating to bill and head shape, eye color, leg color, and overall plumage characteristics, such as the color of the bird’s upper back (silver gray vs. charcoal gray). In addition, gulls typically stay in the open, where they are easily viewed. Insofar as they are often found in places people frequent, gulls are mostly habituated to us and allow prolonged scrutiny and close approach.

Gulls are typically found in open spaces, such as this beachfront in Daytona Beach, Florida (January), and often in areas people frequent on a regular basis. Photo credit: Kevin Karlson.

Gulls are gregarious, often gathering in mixed-species flocks that facilitate direct comparison between known species and less familiar ones—a boon to identification and one that supports a dynamic comparative ID approach. Knowing the identity of a gull standing next to a mystery gull presents observers with a point of reference for size, shape (slender vs. bulky), bill shape, back color (silver gray vs. charcoal gray vs. black), and body shape (plump breasted vs. slender bodied).

While gulls do present an array of plumages typically arranged by successive molts (replacement of feathers), we find that these plumages—especially among the larger, white-headed gulls—may be combined into three broad, manageable age classes. These age classes correspond to the terms that birders commonly use to organize other bird groups, most notably raptors, according to plumage. These age designations are immature, subadult, and adult (breeding and nonbreeding).

Further clarification can then be added to these basic age groups, such as immature/juvenile, immature/1st or 2nd winter, or advanced or retarded immature or subadult. The term “advanced” refers to a plumage state at a particular age that is more complete than usual for a species, and the term “retarded” means that the plumage is less complete than usual at a particular age.

Most smaller to medium-sized gulls take only two years to reach full or mostly adult plumage, and these species typically replace their juvenile upper back feathers in early fall with adultlike grayish feathers. Larger gulls typically take three to four years to achieve full adult plumage, and most typically
acquire various amounts of adultlike upperpart feathers in their second or third year. 

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: What is intelligence?Bird Fact Friday – Traditional Gull ID Problems >>