Although gulls are never numerous in the Rockies, the Ring-billed Gull is the odds-on favorite to be seen. This gull's largest mountain nesting colonies are in the Yellowstone area, but they are occasionally seen throughout the mountains, taking advantage of free meals around landfills and day-use areas. The Ring-bill's population is steadily increasing, along with the northern and western expansion of its range. When Ring-billed Gulls arrive in the Rockies in early spring, their heads are snowy white, but before their fall departure, molting stains their purity with browns. 'Gull' appears to be derived from a Celtic word describing the wailing cry of these birds. The scientific name delawarensis indicates the origin of the first scientifically described specimen-the Delaware River.
I.D.: Sexes similar. Adult: medium-sized; white head; yellow bill and legs; black ring around the bill tip; pale gray back; yellow eyes; black wing tips; black primaries with small white spots; white underparts. Immature: gray back; brown wings and breast.
Size: L 18-20 in. (46-51 cm);
W 48 in. (122 cm); male is slightly larger.
Range: common migrant and local breeder from Rocky Mountain NP north to Montana; uncommon migrant and summer visitor in the Canadian Rockies.
Habitat: large lakes, reservoirs, wetlands, rivers, landfills, golf courses, agricultural fields and public areas, mostly through the montane.
Nesting: in the northern prairies and around the Great Lakes; colonial; often on open beaches, islands or shorelines; on the ground in a shallow scrape lined with plants, nearby debris, grass and sticks; pair incubates 3-6 eggs for 23-28 days.
Feeding: gleans the ground for garbage, arthropods, rodents and earthworms; scavenges; surface tips for aquatic invertebrates and fish.
Voice: high-pitched kakakaka-akakaka; also a low, laughing yook-yook-yook.
Similar Species: California Gull: much larger; no bill ring; dark eyes. Herring Gull: larger; pink legs; no bill ring.