Between 1988 and 1992, we conducted the first comprehensive survey of the number and breeding distribution of the New Zealand Dotterel (Charadrius obscurus) on Stewart Island. The population forms three post- breeding flocks, two of them on Stewart Island; band sightings have confirmed an earlier suggestion that the flock at Awarua Bay, Southland, is also composed of birds from the island. The population is widely spread over difficult terrain during the breeding season; autumn counts of the flocks provide the only practical means of assessing population size. Comparisons with earlier counts show that the population has declined to about one-fifth of its former size in the past 37 years The population is critically endangered because the decline continues and only 60-65 dotterels remain. Average annual mortality of banded adults between 1990 and 1992 was 23%. The major reason for the decline is believed to be predation by feral cats. Band sightings suggest that, apart from Southland, most or all of the recent NZ Dotterel records from the South Island coast (including Farewell Spit) are of juveniles wandering from Stewart Island.