Distinctive and often noisy and conspicuous. The only dark gull in its range in the Humboldt Current. Common over inshore waters and along the coast on sandy beaches, at river mouths, and on adjacent rocky coasts, but breeds inland in remote areas of the Atacama Desert. Breeding adult has a white head while immatures are brown overall; all ages have slender black bill and dark legs. Immatures look like adults in 3 years.