| Sooty Gull | |
|---|---|
 | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Charadriiformes |
| Family: | Laridae |
| Genus: | Ichthyaetus |
| Species: | Ichthyaetus hemprichii |
The Sooty Gull (Ichthyaetus hemprichii), also known as the Aden Gull or Hemprich's Gull, is a mostly coastal species of gull native to the Middle East and East Africa.
Description[]
Possibly 1st summer or 2nd winter Sooty Gull in flight.
Immature bird with a developing red bill tip.
Sizes of this medium-sized, elongated gull range from 43-48 cm in length and 400-510 g in mass along with a 105-118 cm wingspan. Adult Sooty Gulls are white on most of the tail, rump, underparts, sides of the neck, thin crescent above and tiny stripe below the eye, and dark brown on the bib, neck, head and most of the upperparts. They have a distinctive, bicolored long bill with a black ring that separates the mostly orange-red tip from most of the yellowish-green bill, though those of juvenile birds, which lack the white on the neck sides, are paler and variegated on the upperparts, and have way darker flight feathers, (almost) lack the orange-red bill tip and are more silvery. The primary flight feathers are darker than most of the upperparts. There is a white trailing edge on the flight feathers. Most of the underwings, while dark, are slightly paler than the upperwings. The legs are greyish or yellowish-olive. 1st year birds resemble juveniles but with uniformly brown mantle and scapulars, creating a dark “saddle”. Hood and bib become darker in 1st summer. 2nd winter birds, whose legs start to become greener and red bill tips develop at 2nd summer and 3rd winter, are like adult birds but with a paler hood and bib, absent white neck sides, blacker flight feathers and variable dark band on the tail feathers. The species is similar to the related, sympatric White-eyed Gull, both of which develop full adult plumage in 3 years and coexist in the Red Sea, but has a browner adult plumage, thicker bill, and is slightly larger and heavier.
Voice[]
Birds are most noisy in flocks, but rather quiet when alone. Members of the flocks give nasal, down slurred “weeooo… weeooo…” calling in loud chorus. Their alarm calls are a Herring Gull-like “ke-ke-ke-ke”. On the breeding grounds, the long call is a series of loud, screaming notes going lower in pitch. It is described as a loud “kioow” repeated 12-16 times.
Behavior[]
Similar to that of larger gulls, the Sooty Gull has a slow, steady flight.
Feeding[]
With the roles of a predator and scavenger, the Sooty Gull primarily eats discarded or dead fish and fish offal, but also eats other small fish caught by itself, molluscs, prawns, turtle hatchlings and the eggs and chicks of other seabirds. It feeds mainly inshore and in the intertidal zone, occasionally up to 140 km offshore. It also follows ships for offal and is rarely seen plunge-diving for fish. While it usually forages alone, it may be highly gregarious at times. As it is a serious local predator of eggs and chicks in colonies of other seabirds, this seabird is a cause of threat to other species that exist nearby. As a very opportunistic species, it also performs kleptoparasitic mechanisms to steal food from other seabirds. From an observation in Egypt, two adults have performed “prey-dropping” behaviour before to eat the food. This behaviour is well known but not in this species. One gull was carrying a large bivalve of family Verenidae in the bill while rising in flight up to six metres above the ground. Then, it dropped the shell on the rock below. The shell broke immediately and the gull dived head first to eat the mollusc. This behaviour was repeated by the first gull and another one, both with success.
Breeding and Nesting[]
Breeding mostly in Summer, usually between April and October, the Sooty Gull usually nests colonially, e.g. in small loose colonies on the larger islands in the Gulf of Aden and Red Sea, protected by live reefs with rock, sand and sparse vegetation, or sporadically solitarily, e.g. in Africa, with 1-3 pairs per island often among colonies of other seabird species. Its nest may be a bare scrape or depression in the coral in an exposed, unprotected area or may be kept safe by a coral overhang or sheltered beneath a low-growing mangrove or a seepweed bush. A chick or chicks hatch out from 1 to 3 eggs after 25 days of incubation probably performed and shared by both parents. Some young birds fledge in November, but more information is needed on this.
Distribution and Habitat[]
The Sooty Gull can be found in the Red Sea and Gulf of Aden, in the Persian Gulf and Gulf of Oman, east to south Pakistan and south to northern Kenya (Kiunga Islands). It is a maritime species, mainly occurring and breeding along coasts and on islands, also found near harbours and ports, and almost never ever reaching inland. This species may frequent several habitat types including dense vegetated areas, gravel habitat, rocky habitat and sandy areas, though a study confirms that it prefers rocky substrates. It is partly migratory or nomadic, with most populations carrying out southern post-breeding dispersal movements in September-November. Vagrant populations of this seabird have been noted in India, Sri Lanka, the Maldives, Jordan, Lebanon, Israel and Bahrain.
Status[]
This widely distributed species is unsafe from oil spills and degradation of habitat caused by oil prospection in the Gulf region. Eggs are frequently stolen by humans in Pakistan and are taken for human consumption in the Seychelles. The population ranges from 150,000 to 500,000 individuals. Despite the supposedly declining population, it has been examined that this species is not globally threatened and is currently evaluated as Least Concern by the IUCN.