Nesting adult Seychelles Sooty Terns (Sterna fuscata) were banded in five colonies. Searches for banded birds were made annually during the incubation phase of the breeding cycle. Within the colonies on Bird Island (largely protected from human intrusion) and Desnoeufs Island (from half of which eggs are harvested annually), differences in the tendency to return to nest sites used in earlier years were attributed to the effects of human disturbance, especially egg collecting. On Bird Island, the only colony that was searched intensively for banded birds each year between 1994 and 2001, eighteen birds were found that had formerly nested in other colonies. These inter-colony movements of breeding adults were also attributed to human disturbance in source colonies, but changes in food distribution may have stimulated birds to move from a colony that was protected from human interference. The finding that breeding adult Sooty Terns sometimes switch colonies suggests that these Seychelles colonies should be regarded as units within a metapopulation, with genetic exchange between units. This must be taken into account when estimating the allowable harvest of eggs, for human consumption, undertaken in the Seychelles.