Casual observers often lump all gulls together as “sea gulls,” which infuriates birders, who view gulls as one of the most interesting groups of birds. But while a few gull species are distinctive, it’s sadly true that “sea gulls” are a closely related, generally similar group of species: large birds with heavy, yellow beaks, gray wings and backs, and white heads and underparts.
Gull identification is complicated by this overall generic look. It’s complicated even more by the fact that the larger gull species pass through a succession of different plumages during the first three or four years of their lives, generally trending from mottled and brownish in their first year to the familiar gray and white of adult “sea gulls.”
But despite these challenges and the untidy tendency of some gull species to hybridize, differences really do exist — in size, coloration, distribution, and behavior. Winter, being peak gull-watching season in our region, is the best time to spend time observing gulls. With a little close attention, you’ll realize that the imprecise term “sea gull” lumps together a bunch of very different birds.
A good species to focus on as a beginning gull-watcher is the ring-billed gull, Larus delawarensis. This bird, rather delicate by the standards of the larger gull species, is one of our most common gulls in winter (though it does not breed here, and disappears quite abruptly every spring). In keeping with the gregarious habits of gulls in general, ring-bills generally turn up in groups, often part of larger, mixed-species flocks. Vineyard Haven’s inner harbor and boat launch, the Oak Bluffs waterfront including Ocean Park, and the shoreline around downtown Edgartown are reliable places to find this species.
On the Vineyard, ring-billed gulls typically mix with their larger, more numerous relative, the herring gull. Such a mixed flock is a great learning opportunity, making it possible to compare characteristics of multiple species.
As the name suggests, a neat black ring completely encircling the bill is a classic field mark of the ring-billed gull (at least of adult individuals). Some immature herring gulls show dark marking on the bill, but never a complete ring. So this field mark is a great place to start; once you’ve located a ring-billed gull on the basis of that mark, you can look for all the other ways this species differs from its abundant relative.
About two-thirds the size of a herring gull, a ring-billed gull will stand out in a mixed flock as a clearly smaller, more delicate bird. The gray of the back and wings is usually subtly darker than the corresponding parts on a herring gull (though gull coloration is notoriously dependent on the light). The legs on a ring-billed gull are yellowish, sometimes bright, sometimes tinged with green; in any case, nothing like the pink legs of an adult herring gull. Even the structure of the head — with a smallish bill and a rounded crown — differs obviously from the more menacing scowl of a herring gull.
Ring-billed gulls have had a difficult history with humans. Many of their nesting sites have succumbed to development, and the birds themselves were persecuted for many years, depleted by egg harvest and by shooting (like most gulls, ring-bills have been regarded as competitors with human fisheries). Numbers hit a nadir in the early 20th century, but began rebounding as destructive practices faded from vogue. At present, very roughly, some 10 million ring-billed gulls inhabit the continent.
While one thinks of “sea gulls” as mainly coastal, the ring-billed gull is primarily a bird of inland waters. The aboriginal center of its range was the St. Lawrence River system and the Great Lakes, though they breed in a wide variety of wet settings across most of southern Canada and the northernmost U.S. There are a few historical breeding records for Massachusetts, but at present, the species does not nest here, and is usually absent in the summer. In winter, ringers move south, using both coastal and inland sites from southern New England down to the Gulf Coast.
Many nesting colonies are sited in remote areas, perhaps a response by the ring-billed gull to past persecution. But away from the breeding grounds, this gull enthusiastically takes advantage of human activity. Their fondness for parking lots (often a source of food spilled or dropped by humans) is legendary among birders; in particular, ring-bills seem to like nothing better than a handful of french fries. But deprived of human assistance, ring-billed gulls do just fine catching and eating small fish and mollusks.
Superficially, ring-billed gulls may resemble their relatives. But get to know these elegant birds, and you’ll never call them “sea gulls” again.