Friday, 20 January 2017

Common gull (Larus canus) - Θυελλόγλαρος - Cyprus

The common gull (Larus canus) is a medium-sized gull which breeds in northern Asia, northern Europe and northwestern North America. The North American subspecies is commonly referred to as the mew gull, although that name is also used by some authorities for the whole species. It migrates further south in winter. There are differing accounts as to how the species acquired its vernacular name

Adult common gulls are 40–46 cm (16–18 in) 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.

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 (sometimes just one or two); 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 (possibly as much as 80-90%) of the world population. By contrast, the Alaskan population is only about 10,000 pairs.

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

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 (palest subspecies); wingtips with extensive black; iris dark. Wingspan 110–125 cm (43–49 in); mass 290–480 g (10–17 oz).
L. c. heinei – Homeyer, 1853 – Russian common gull. Found in central northern Asia. Medium size; mantle dark grey (darkest subspecies); wingtips with extensive black; iris dark. Mass 315–550 g (11.1–19.4 oz).
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 394–586 g (13.9–20.7 oz).
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 96–102 cm (38–40 in); mass 320–550 g (11–19 oz).

Photos and video Akrotiri  11/1/2017 by George Konstantinou

No comments:

Post a Comment