The Crab Plover (Dromas ardeola) is a little-known shorebird that breeds colonially in self-dug burrows on islands in the north-western Indian Ocean. To test whether the “nest site limitation” hypothesis could satisfactorily explain the high nest density in this species, 21 colonies were studied in Eritrea from 2002 to 2009. The hypothesis was falsified by the following observations: across the study period, nesting colonies were relocated on the same sandbanks every year and most occupied no more than 4% of the area suitable for excavating burrows; colony size and area suitable for burrowing were not correlated; nest density and colony size were not significantly correlated; the area occupied by nests increased steadily throughout the nest-building period; nests were closely-spaced throughout the building phase rather than being scattered throughout the area eventually used for digging. These results indicate that the Crab Plover is not site-limited but a truly colonial species.