| Audouin's Gull | |
|---|---|
 | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Charadriiformes |
| Family: | Laridae |
| Genus: | Ichthyaetus |
| Species: | Ichthyaetus audouinii |
Audouin's Gull (Ichthyaetus audouinii) is a threatened gull found in the Mediterranean. It was first described in 1826.
Taxonomy[]
Previously included in the genus Larus, this species has now been separated into a new genus, Ichthyaetus, along with the Mediterranean Gull.
Description[]
This bird is 44-52 cm long with a 117-128 cm wingspan. It resembles a Larus gull because of its mostly white plumage, grey wings and back, and black wingtips with small, hardly visible white spots; however, it is slightly smaller and more delicate, with a rather slender body, long, narrow wings, and a proportionately smaller, thinner bill. It has greenish-grey legs and a red bill with a black-and-yellow tip. The juvenile is rather uniformly grey-brown, with relatively little streaking and mottling; it has a dark tail, a white U-shaped rump-patch, and dark underwings with conspicuous pale patches.
Voice[]
Its call is a raucous "keeek keeek keeek".
Behaviour[]
In flight.
Audouin's Gull has a light, tern-like flight. Unlike most other gulls, which are versatile and adaptable, this species is strictly coastal or pelagic, never venturing inland. Usually, but not necessarily, gregarious during the breeding season, the gull becomes more solitary in winter, when it straggles along coastal lagoons and sandy shores.
Feeding[]
This gull occupies a restricted ecological niche. It hunts on the high seas like Shearwaters do, feeding mostly on small fish and cephalopods, snatched in flight from the surface or in deeper plunge-dives. It rarely scavenges. The distribution of Audouin's Gull's prey is variable and depends on sea currents and weather conditions, therefore, this gull moves around a lot.
Breeding[]
Audouin's Gull nests in colonies or singly on rocks and small islands. Year after year, old colonies may be abandoned and new ones may be founded in previously unoccupied territories. Nesting occurs from March to August. The courtship display begins in mid-air, with the two partners flying together over the colony as the male makes its territorial call. The two then glide down to the place they have chosen as their nesting site, with the male continuing to call, jerking its head backwards. They then start walking in circles, side by side, with their bills pointed downwards. Eventually, the male feeds the female, and mating occurs. The nest is located in a shallow depression on the ground, lined with stems, twigs and aquatic plants. The best locations, usually at the centre of the colony, are reserved for the oldest, most dominant couples. The clutch is 2-3 cream-coloured eggs with dark spots. Incubation lasts for about 4 weeks. The chicks peck the spot on tip of their parents' bills, which stimulates the adults to regurgitate their food. Fledging occurs about 8 weeks after hatching. This gull breeds once a year.
Distribution and habitat[]
This species breeds exclusively in the Mediterranean basin, with the vast majority of couples nesting in the western Mediterranean. The largest colony resides in the Ebro delta, Spain. Other colonies are found in the Chafarinas Islands and in the Balearic Islands. The eastern population mostly inhabits the islands of the Aegean Sea, Cyprus, and the southern coast of Turkey. The population of the central Mediterranean, mostly concentrated in Corsica, Sardinia and northern Tunisia, appears to be the smallest and most erratic, frequently changing their nesting sites. Some individuals cross the Strait of Gibraltar in winter and may end up reaching the Atlantic coast of tropical Africa.
Conservation[]
Audouin's Gull is one of the rarest European birds. The main threat to this gull is water pollution. Since, unlike Yellow-legged Gulls or Black-headed Gulls, it cannot rely on other food sources, it is particularly vulnerable to mercury poisoning from eating tainted fish. Other threats include the destruction of inhabitable coastlines and nest predation by other birds. Prior to 2010, populations had been increasing significantly in the western Mediterranean, however, in recent years, they have suffered a decline after the collapse of the largest breeding colony.