The Westland petrel (Procellaria westlandica) is endemic to New Zealand, and nests within a restricted area of the West Coast of the South Is. Surveys of burrow occupancy rate in 2 colonies in 2001 using burrow-scopes showed an average of 21% of burrows contained a chick or egg. The rate was c. 50% of that recorded for other burrowing seabirds and surveyed using burrow-scopes. These findings may suggest that the breeding population may have declined in recent years, or that a large group of non-breeding birds maintain territories on the colonies. Further work is planned to test the 2 opposing hypotheses.