Ring-billed Gulls

Today we're taking a closer look at one of the most common, most easily observed North American birds, the Ring-billed Gull. Somebody was feeding these birds yesterday on the Inwood Hill Park Bay, providing me with close range photo opportunities. Practically anyone in North America can easily observe these birds most of the year, and if you've done so extensively, this post is probably not going to show you anything you didn't already know.

It's a three-year gull, meaning the bird goes through three plumage cycles to reach the adult basic (non-breeding) or alternate (breeding) plumages.

This is a first cycle bird. The eyes are dark; the bill and legs are pinkish; the black on the bill hasn't become a ring yet; the majority of the mantle feathers are brown; the tail is white with a broad black band. Some brown juvenal feathers are being replaced by grey second cycle feathers, such as the mantle feathers and tertials.

Same individual. Note the brown smudges all over the head and neck. In winter, first and second cycle birds show such extensive mottling, while adults in basic (winter) plumage show limited mottling on the head. See for example the middle bird in the top picture.

Still the same individual, photographed merely seconds after the previous photo was taken. Plumage-wise we're not seeing anything different, but note how the head shape is subtly different now that the bird is more alert. In larophology, larophiles often stress the shape and structure of the bird, because plumage is so tremendously variable in this family. This may be true, but so is shape!

Here's a head detail of a second cycle bird. The bill now has a ring, and the tip of the bill is already yellow. The proximal part of the bill is now greenish gray. Note that there is considerable variation in coloration of bare parts also, so not every second cycle ringbill is going to show a gray bill in winter.

Same bird. Not only the bill is gray - so is the eye. The spotting on the head and neck seems less than on the first cycle bird, but more than on the basic plumage bird. Although this bird is intermediate in age class, I don't think the intermediate spotting is age-related; I believe it to be rather a function of individual variation. Anyone wishing to correct me on this, please do!

Again the same bird. Note how this second cycle plumage resembles the basic plumage. Two major differences are obvious in this photo: color of bare parts, and absence of white spots in the wings. The birds standing behind the second cycle bird are both in basic plumage, with yellow, not gray legs, and with white spots in the wingtips.

All these birds were photographed 14 February 2010 in Inwood Hill Park, Manhattan. The previously reported ringbill with an auxiliary marker (APP) was still present. I haven't heard back yet where this bird was banded.