Unusual among gulls, it breeds inland in the extremely dry Atacama Desert in northern Chile, although it is present as a non-breeding bird along much of the Pacific coast of South America.

It is a vagrant to Mexico, the Galapagos, Guatemala, Brazil, Argentina, Panama[1] and Florida;[4] an earlier report of it in Louisiana, from 1987, has not been accepted by a birdwatching authority.

Its chief predator is the turkey vulture (Cathartes aura) and when threatened, the incubating parent sometimes leaves the nest temporarily, and when this happens the eggs need to have impervious shells in order to avoid losing too much water through evaporation.

The typical habitat of the grey gull is sandy beaches and mudflats along the western coasts of South America where it probes with its beak in the sediment for invertebrate prey,[3] particularly mole crabs.

However, the total number of birds is sufficiently large to justify listing the grey gull as being of "least concern" rather than including it in a more threatened category.