 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.In fact, the evaporative loss from the eggs is found to be about one third of that which occurs in Heermann's gull ("Larus heermanni"), another desert nesting species.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, particularly mole crabs.