Adult common gulls are long, noticeably smaller than the herring gull and slightly smaller than the ring-billed gull. It is further distinguished from the ring-billed gull by its shorter, more tapered bill, which is a more greenish shade of yellow and is unmarked during the breeding season. The body is grey above and white below. The legs are greenish-yellow. In winter, the head is streaked grey and the bill often has a poorly defined blackish band near the tip, which is sometimes sufficiently obvious to cause confusion with ring-billed gull. They have black wingtips with large white "mirrors". Young birds have scaly black-brown upperparts and a neat wing pattern, and grey legs. They take two to three years to reach maturity. The call is a high-pitched "laughing" cry.
Taxonomy
There are four subspecies, two of which are considered distinct species by some authorities:
L. c. canus – Linnaeus, 1758 – common gull. nominate, found in Europe and western Asia. Small; mantle medium grey ; wingtips with extensive black; iris dark. Wingspan ; mass.
L. c. heinei – Homeyer, 1853 – Russian common gull. Found in central northern Asia. Medium size; mantle dark grey ; wingtips with extensive black; iris dark. Mass.
L. c. kamtschatschensis – Bonaparte, 1857; syn. L. kamtschatschensis – Kamchatka gull. Found in northeastern Asia. Large; mantle medium-dark grey; wingtips with extensive black; iris pale. Mass.
L. c. brachyrhynchus – Richardson, 1831; syn. L. brachyrhynchus – mew gull or short-billed gull. Found in Alaska and western Canada. Small; mantle medium-dark grey; wingtips with little black and much white; iris pale. Wingspan ; mass.
Ecology
Both common and mew gulls breed colonially near water or in marshes, making a lined nest on the ground or in a small tree; colony size varies from 2 to 320 or even more pairs. Usually three eggs are laid ; they hatch after 24–26 days, with the chicks fledging after a further 30–35 days. Like most gulls, they are omnivores and will scavenge as well as hunt small prey. The global population is estimated to be about one million pairs; they are most numerous in Europe, with over half of the world population. By contrast, the Alaskan population is only about 10,000 pairs.
Vagrancy
The common gull occurs as a scarce winter visitor to coastal eastern Canada and as a vagrant to the northeastern USA. There is one recent record of a mew gull in Europe, on the Azores in 2003.
Etymology
The scientific name is from Latin. Larus appears to have referred to a gull or other large seabird, and canus is "grey". The name "common gull" was coined by Thomas Pennant in 1768 because he considered it the most numerous of its genus. Others assert that the name does not indicate its abundance, but that during the winter it feeds on common land, short pasture used for grazing. John Ray earlier used the name common sea-mall. It is said that uncommon gull is a more accurate description. There are many old British regional names for this species, typically variations on maa, mar and mew.
