| Caspian gull | |
|---|---|
_summer_Danube_delta.jpg) | |
| Adult in summer plumage, Romania | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Charadriiformes |
| Family: | Laridae |
| Genus: | Larus |
| Species: | L. cachinnans |
| Binomial name | |
| Larus cachinnans Pallas, 1811 | |
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| Range ofL. cachinnans Breeding Resident Non-breeding | |
TheCaspian gull (Larus cachinnans) is a largegull and a member of theherring and lesser black-backed gull complex. The scientific name is fromLatin.Larus appears to have referred to a gull or other large seabird, andcachinnans means 'laughing', fromcachinnare 'to laugh'.[2]
It is a large gull at 56–68 cm (22–27 in) long, with a 137 to 155 cm (54 to 61 in) wingspan and a body mass of 680–1,590 g (1.50–3.51 lb).[3][4] Among standard measurements, thewing chord is 38.5 to 48 cm (15.2 to 18.9 in), thebill is 4.6 to 6.4 cm (1.8 to 2.5 in) and thetarsus is 5.8 to 7.7 cm (2.3 to 3.0 in).[4] The Caspian gull has a long, slender bill, accentuated by the sloping forehead. The legs, wings, and neck are longer than those of the herring gull andyellow-legged gull. The eye is small and often dark, and the legs vary from pale pink to a pale yellowish colour. The back and wings are a slightly darker shade of grey than the herring gull, but slightly paler than the yellow-legged gull. The outermostprimary feather has a large white tip and a white tongue running up the inner web.
First-winter birds have a pale head with dark streaking on the back of the neck. The underparts are pale and the back is greyish. The greater and medianwing coverts have whitish tips forming two pale lines across the wing.
The Caspian gull breeds around theBlack andCaspian Seas, extending eastwards acrossCentral Asia to north-westChina. In Europe, it has been spreading north and west and now breeds inPoland, easternGermany, southernRussia and all year round inUkraine. Some birds migrate south as far as theRed Sea andPersian Gulf, while others disperse intoWestern Europe, in countries such asSweden, Norway and Denmark or the Benelux and even North of France. Small numbers are now seen regularly inBritain, especially inSouth-east England,East Anglia, and theMidlands.
It typically nests on flat, low-lying ground by water, unlike the yellow-legged gull, which mainly nests on cliffs in areas where the two overlap. The breeding season starts from early April. Two or three eggs are laid and incubated for 27 to 31 days.
They arescavengers andpredators with a very varied diet. During the breeding season, they often eatrodents such asground squirrels, flying some distance into the steppes to find them.
This form has a troubled taxonomic history, summarised in theherring gull article. The Caspian gull used to be treated as a subspecies of the herring gull, but it is now treated as a full species by many authorities (e.g. theBritish Ornithologists' Union records committee). Some authorities include the yellow-legged gull (L. michahellis) withinL. cachinnans, but it is also now commonly considered to be a separate species.
The steppe gull or Baraba gull (L. (cachinnans) barabensis) may be regarded as a subspecies of the Caspian gull or as a separate species. It is also very similar genetically to its northern neighbour, thetaimyrensis race ofHeuglin's gull. The steppe gull breeds in Central Asia, particularly northernKazakhstan. Its nonbreeding range is still little-known, but most are thought to winter in southwestern Asia from the Persian Gulf to northwesternIndia. There are possible records of this form fromHong Kong andSouth Korea.
TheMongolian gull (L. (vegae/cachinnans) mongolicus) may be classed as a subspecies of the Caspian gull, a subspecies of theVega gull, or as a species in its own right. It breeds inMongolia and the surrounding areas and migrates southeast in winter.
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