The Hartlaub's gull (Chroicocephalus hartlaubii), also colloquially known as the king gull, is a small, nimble seabird with a length of 36–38 cm. Its plumage is predominantly white, complemented by a grey back and upperwings. The wingtips are black, adorned with striking white "mirrors." A notable feature is its dark red bill and legs. During the breeding season, it sports a very faint lavender grey hood, while outside of this period, its head remains plain white. Both sexes exhibit similar markings. The Hartlaub's gull is distinguishable from the slightly larger grey-headed gull by its thinner, darker bill, deeper red legs, paler head, and dark eyes. It reaches full maturity in two years, and juveniles can be identified by a brown band across the wings, lacking a black terminal tail band and presenting less dark areas in the wings compared to their grey-headed counterparts.
When observing Hartlaub's gulls, look for the combination of their dark red bill and legs, the white "mirrors" on the black wingtips, and the faint grey hood during breeding season. Juveniles will have a brown band on the wings and darker legs, with a white head that distinguishes them from similar-aged grey-headed gulls.
