Bird of the Month: Mew Gull, Ring-billed Gull, California Gull
By Andy McCormick
PC: Mick Thompson (Mew Gull)
Larus canus/ Larus delawarensis/ Larus californicus
Length 16 in 17.5 in 21 in
Wingspan 43 in 48 in 54 in
Weight 15 oz 1.1 lb 1.3 lb
AOU Band code MEGU RBGU CAGU
In the northwest we have three species of gulls with white heads and yellow legs: Mew Gull, Ring-billed Gull, and California Gull. They differ in size, bill markings, mantel color, and wing tip appearance. In this article we will compare and contrast only the adult plumage birds. All three species are in the very large (23 species) genus Larus, from the Greek, laros, a ravenous seabird. The Mew Gull has the species name canus, from the Latin for white haired in reference to its plumage. Mew is old English for gull. The Ring-billed is delawarensis referring to the Delaware River where it was found. The California is californicus referring to the state where it was collected (Holloway).
It may be most helpful for identification to learn the Ring-billed Gull very well. This bird is ubiquitous in North America and has a population of 3-4 million individuals making it our most populous gull. Its medium size makes it a good reference bird for comparison with many other gulls. It has a medium-size bill with a clean-cut, black subterminal ring (Alderfer). Its eyes are pale with a dark orbital ring. In winter the head becomes finely streaked. The black wing tips are set off by white mirrors toward the end of the outer two primary feathers (numbered P9 and P10).
The Mew Gull is smaller than the Ring-billed and it has a much smaller, unmarked bill. The Mew also has black wing tips but the mirrors are much larger and reach to the tips of P9 and P10, and look large when the bird is in flight. This gull has a floating flight pattern and compared to the Ring-billed is more delicate with a gentle expression (Sibley). It is seen along coastal waters in winter. It breeds in boreal lakes in Alaska and northern Canada, but is seldom seen inland outside of breeding season. In first and second winter birds the legs can be fleshy or greenish colored.
The California Gull is larger than the Ring-billed with a stouter, but straighter bill. There is a narrow black ring on the bill, and next to it is a red spot at the gonys, the area on the lower mandible between the tip and angle of the bill. The eye is dark with a red orbital ring. The legs are yellow and sometimes have a greenish tinge. The wing pattern is distinctive. The tips are black with large mirrors on P9 and P10, and there is more black on P7 and P8 giving the wing a squared-off appearance (Alderfer).
All three species are opportunistic omnivores. The Ring-billed especially can be found in parks, land fills, and feeding at garbage cans around fast-food restaurants. Some Mew Gulls are also learning these behaviors, but generally eat fish, crustaceans, urchins, and inland will eat insects and earthworms. California Gulls will eat fish and other marine life, and in summer will eat large numbers of insects. So much so, that they are attributed with having saved the crops of Mormon settlers attacked by locusts in 1848, inspiring the gull monument in Salt Lake City (Kaufman).