Ring-billed Gull

Larus delawarensis (Ord, 1815)

2022-03-31 Gomel	© Andrey Borodin

Description

Similar to Common Gull, but slightly larger, heavier-bodied, with thicker bill. Adult has pale grey upperwing with diffuse white tertial and rear scapular crescents and trailing edge to the inner wing (in Common Gull, white are contrasting and clean-cut against darker grey upperparts). Wing-tip black with smaller white mirrors on P9-10 than in Common. Bill with solid black bar. Eyes pale yellow (dark on Common Gull). Orbital ring red to orange-red. In winter, head dark-spotted, typically darker and more densely spotted than Common, strongest on hindneck and around eyes. Orbital ring blackish. Bare parts yellow, generally brighter yellow than in Common (especially in summer). Length 41-49 cm, wingspan 115-135 cm.

Distribution

This species has an extremely large range. The Ring-billed Gull breeds in the USA and Canada from north California, east Washington and interior British Columbia, across the prairie provinces, north mountains and plain states. Also from the Great Lakes east to the coast. It winters in the southern portion of its breeding range south to the Gulf Coast, Mexico, Central America, Greater and Lesser Antilles.
In 2022, a vagrant individual was found on the territory of Belarus (Tarsiger.com).

Biology

This species has an extremely large range. The Ring-billed Gull breeds in the USA and Canada from north California, east Washington and interior British Columbia, across the prairie provinces, north mountains and plain states. Also from the Great Lakes east to the coast. It winters in the southern portion of its breeding range south to the Gulf Coast, Mexico, Central America, Greater and Lesser Antilles.
This species inhabites coasts, rivers, estuaries, reservoirs and rubbish dumps. It is a highly opportunistic feeder, owing to its varied diet including fish, insects, earthworms, refuse, offal, fiddler crabs, dates, fish eggs, grain, rodents and birds.<br>At present there are no factors thought to pose a genuine threat to this species

References

BirdLife International (2022) Species factsheet: Larus delawarensis. Downloaded from http://www.birdlife.org on 01/04/2022.

Tarsiger.com (2022). Downloaded from http://tarsiger.com/news/index.php?sp=find&lang=eng&species=16010&sel=1&place=&country=&day=0&month=0&year=0&find_button=Search on 01/04/2022.