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Photo by Jim Parrish
Photo Copyright Jim Parrish
Ring-billed Gull
Larus delawarensis
NatureServe conservation status
Global (G-rank): G5
State (S-rank): S4N
External links
General information
The ring-billed gull, Larus delawarensis, is a common seabird that is frequently seen in areas such as beaches, estuaries, water bodies, fields, parking lots, and garbage dumps. It breeds from inland areas of the northern United States northward into central Canada. Ring-billed gulls spend the winter along coastal regions of North America, in the Gulf States, and in the southern portions of the American Midwest, as well as along the shores of the Great Salt Lake in Utah. The ring-billed gull is a common winter resident in northern Utah, and an occasional transient in other parts of the state. Although nesting colonies have been observed in northern Utah, there is insufficient evidence to believe that breeding occurs there.
Ring-billed gulls typically nest in colonies on rocky, sparsely vegetated islands in large lakes, on lake peninsulas, or on near-shore oceanic islands. In the west, colonies tend to be in close proximity to towns with croplands, which are popular foraging locations. In the east, there does not appear to be a relationship between human populations and the location of breeding colonies, presumably because the food source for the eastern populations is not directly related to human activities. Ring-billed gulls are omnivores; they eat a large variety of items that includes fishes, insects, worms, rodents, and grains. As opportunists, individuals will steal food from other birds, including members of their own species.
A pair bond is formed just before birds arrive at the nesting site; not only do the birds typically return to the same colony site each year, but they also usually select a nesting location in the same specific area of the colony each year. Typically a pair is monogamous for a breeding season, often selecting a mate from a neighboring breeding pair from the previous breeding season. The pair builds a nest of grasses and feathers on matted vegetation, either in the open, or in an area concealed by rocks. Two to four eggs are incubated for about three weeks; both parents share nest roosting duties, but the female spends more time on the nest than does the male. The young remain in the nest for a couple days after hatching, until they are able to walk. Both parents care for the young until they fledge at about five weeks at age, at which time the family group breaks up. The young will attain their adult plumage after three years.
Species range
BREEDING: Washington to Manitoba, south to northeastern California, Colorado, South Dakota; north-central Ontario to Newfoundland, south to eastern Wisconsin, northern Illinois, northern New England and New Brunswick. Nonbreeders occur in summer north to central Alaska, southern Yukon, southern Mackenzie, and southeastern Keewatin, and south through wintering range. NON-BREEDING: coast from southern British Columbia to southern Mexico, rarely south to Costa Rica and Panama; southeastern Canada to Gulf coast, Bahamas, and Greater Antilles; interior from Great Lakes to central Mexico; frequently in low numbers in Hawaii. See Spendelow and Patton (1988) for information on distribution and abundance in coastal U.S., including the Great Lakes region.
Migration
Arrives in northern breeding areas April-May (Bent 1921). Nonbreeders widespread in summer, from Alaska and northern Canada south through wintering range (AOU 1983). Some, mostly first- or second-year birds, reach Central America, mainly early November-late May (Stiles and Skutch 1989).
Habitat
Seacoasts, bays, estuaries, rivers, lakes, ponds, irrigated fields and plowed lands, cities, dumps. Nests rocky, sandy, and grassy islets or isolated shores, occasionally on marshy lands, often with other water birds; mainly at inland lakes. Nests usually placed in low vegetation. See Spendelow and Patton (1988) for additional information.
Food habits
Feeds opportunistically on various animals and plant material (and garbage), usually obtained from land or water surface; sometimes catches flying insects and pulls fruits from shrubs and trees.
Ecology
Fox predation may result in reproductive failure of local breeding colonies (Southern et al. 1985). May prevent terns from nesting by usurping habitat. Breeding individuals foraged an average of 11 km from colony (Baird 1977).
Reproductive characteristics
Eggs are laid in May-June. Clutch size usually is 3. Incubation, by both sexes, lasts about 21 days. Young are tended by both parents, fed until able to fly. Usually attains adult plumage in 3 years. May form female-female pairs or polygynous trios.
References
- Ehrlich, P. R., D. S. Dobkin, and D. Wheye. 1988. The birder’s handbook[:] a field guide to the natural history of North American birds. Simon & Schuster, New York. xxx + 785 pp.
- Behle, W. H., Sorensen, E. D. and C. M. White. 1985. Utah birds: a revised checklist. Utah Museum of Natural History, Occasional Publication No. 4. Salt Lake City, UT.
