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).

This species is 37-40 cm long with a 90-102 cm wingspan. It is therefore slightly larger than the Black-headed Gull, which it resembles, although it does not have a black hood in summer. 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 pink colouration. This bird takes two years to reach maturity, as usual in gulls. First year birds have a black terminal tail band, and dark areas in the wings. The scientific name of this bird commemorates the Italian naturalist Giuseppe Gené.

This rather uncommon gull breeds in colonies, nesting on the ground and laying up to three eggs. Like most gulls, it is gregarious in winter, both when feeding or in evening roosts. It is not a pelagic species, and is rarely seen at sea far from coasts. It is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.