The underside of their wing is pale gray with a blackish outer half but for large white "mirrors" on the three outermost primaries.

[8][9] The Andean gull is found year-round in the Andes from far southwestern Colombia south through central Ecuador and Peru, western Bolivia, and eastern Chile and western Argentina to about the latitude of the north of Chile's Aysén Region.

Many individuals winter on the coast from central Peru south into northern Chile, but it is not known if these are from the highlands to the east of there or from the southern part of its range.

[8][9] In its breeding season the Andean gull is found at lakes, bogs, marshes, and fields of the puna and páramo zones of the Altiplano.

[8][9] In the mountains the Andean gull feeds on earthworms, insects, amphibians, small fish, and occasionally eggs and chicks of waterbirds.

The Andean gull's vocalizations include "agitated, sometimes tremulous “yeeer” calls" and "a hoarse “raggh-aggh-keeaagh” and other low raspy notes.

[1] "The species is probably vulnerable, with no large populations...breeding areas are in remote high-altitude lakes but many are increasingly subject to agricultural pressure and human disturbance.