Herring gulls are large gulls with stout bills. Adults have light-gray backs, black wingtips, and white heads and underparts. Juveniles are mottled brown. The legs are dull pink at all ages. Herring gulls breed on islands in the Great Lakes and can be found following fishing boats and feeding in habitats as diverse as open water, mudflats, plowed fields, and garbage dumps. They are loud and competitive scavengers, happy to snatch another bird's meal and are often found in large congregations.
These colonial nesting birds make nests of soft soil, sand, or short vegetation. To protect the nest from prevailing winds and hide it from predators, it is usually placed next to a rock or vegetation. This also hides it from the nearest neighbors. Crevices may be used as nest sites in rocky areas. After chicks hatch, both parents feed them day and night for up to 12 weeks, splitting foraging shifts to offer each chick up to half a pound of food per day as it nears fledging.
Young herring gulls are more migratory than adults. In the Great Lakes, most adults remain near their breeding grounds, but the nonbreeders move farther south in the fall.