The slender-billed gull (Chroicocephalus genei) is a mid-sized gull which breeds very locally around the Mediterranean and the north of the western Indian Ocean (e.g. Pakistan) on islands and coastal lagoons. Most of the population is somewhat migratory, wintering further south to north Africa and India, and a few birds have wandered to western Europe. A stray individual was reportedly seen on Antigua, April 24, 1976 (AOU, 2000).
The genus name Chroicocephalus is from Ancient Greek khroizo, "to colour", and kephale, "head". The specific genei commemorates Italian naturalist Giuseppe Genégs
This species is 37 to 40 cm (14.6 to 15.7 in) long with a 90 to 102 cm (35.4 to 40.2 in) wingspan. It is therefore slightly larger than the black-headed gull, which it resembles, although it does not have a black hood in summer. It has a pale grey body, white head and breast and black tips to the primary wing feathers. The head and dark red bill have an elongated tapering appearance, and this bird also appears long-necked. The legs are dark red, and the iris is yellow. In summer, the breast has a faint pink coloration. This bird takes two years to reach maturity, as is usual in gulls. First year immature birds have a black terminal tail band, and dark areas on the wings
The slender-billed gull breeds in lagoons and lakes around the Mediterranean Sea and in similar locations in countries bordering the northwestern part of the Indian Ocean. In 2010 a successful colony was found breeding on an island in a mountain lake in Algeria. The lack of predators and disturbance allowed over 98% of the eggs to hatch. It overwinters on the coast in estuaries and bays. It feeds in deltas, marshes and grassland. It is one of a number of species of gull to feed on landfill sites