Courtsey Kenn Kaufman
The Ring-billed Gull's range has expanded exponentially since the 1960s, and at various times it may be found anywhere in North America south of the boreal forests. These gulls breed across the middle section of North America, from coast to coast, with concentrations in northern California, the Great Plains, the Great Lakes, and the St. Lawrence Seaway. The Ring-billed Gull's wintering range covers most of the United States, with the exception of the upper Great Plains, parts of the Rocky Mountains, and the desert southwest. In winter, they concentrate around human habitations, landfills, and coasts.
A legend for the range map to the right can be found here
The Ring-billed Gull lives on land near water and has adapted well to human alteration of its historic habitat. It breeds on sparsely vegetated islands and small peninsulas. Fresh water lakes, bays, large rivers, and reservoirs are preferred, but the coasts may be used as well. Western populations usually nest within 20 miles of a town with at least 1,000 people. At all times of the year, farmland is important for Ring-billed Gulls, but they also forage in parks, golf courses, malls, fast food restaurant lots, landfills, and waste treatment facilities.
The Ring-billed Gull is omnivorous and eats whatever is available. With long strides, it searches for prey over beaches, lawns, fields, and garbage heaps. Stirring mud in the shallows, chasing insects on the wing, and diving or dipping into the water, this gull often forages in flocks. Its diet includes many fish (alewife, stickleback, and perch), insects (true bugs, beetles, cicadas, flies) grain, rodents, and earthworms.
In colonies numbering as many as 80,000 pairs, Ring-billed Gulls nest on the ground, usually near logs, low plants, or human refuse. Males establish small territories and attract mates with long calls and ritualized postures. The pair bonds are cemented when the female begs for food, which the male regurgitates and she eats. Nest may vary from barely a scrape to an arrangement of sticks, grasses, leaves, and mosses. For the duration of the season, the pair cooperates in all phases of breeding.
Some Ring-billed Gulls have an unusual breeding pattern. Up to 8% of breeding pairs, usually in large and expanding colonies, are comprised of two fertilized females that cooperate in rearing a combined brood. The two to three olive to gray eggs are incubated for 23 to 28 days. The gray, downy chicks are initially helpless, but can walk within two days and swim within three. The hatchlings' defenses include running away, crouching to hide, and attacking. They eat most adult foods, which are regurgitated onto the ground. Ring-billed Gulls fledge in 40 to 45 days, and the familial bonds dissolve.
Comprised of individuals or loose flocks, migration is disorganized and follows a wide dispersal of Ring-billed Gulls after breeding in the fall. Migration is most noticeable in October and complete by December. Ice cover and food shortages regulate winter migration. Some Ring-billed Gulls use traditional staging areas like the eastern Great Lakes and routes like the passage from the Great Lakes to the east coast, then southward into Florida. Spring migration peaks in March and April, and is relatively brief.