Sooty shearwater ( Puffinus griseus ) breeding colonies on mainland South Island, New Zealand: Evidence of decline and predictors of persistence

A survey of 170 km of the mainland Otago coastline was carried out in the 1997/98 breeding season in order to determine the current status of breeding colonies of sooty shearwater ( Puffinus griseus ). The locations of breeding colonies, as defined by the presence of burrows, are described and compared with historical records. Numbers of colonies were found to have declined by at least 54% in the past 50 years. Site characteristics which may predict colony survival were: (1) control of introduced predators and (2) the presence of softer soils. Persistence of burrows was independent of dominant vegetation type. Sooty shearwaters seem to be able to withstand habitat modification, but most of the small colonies recorded in this survey are unlikely to survive without predator control.