Previous exploration and ornithology in the Rauer Group are reviewed. Estimates of the nesting populations of southern fulmars and Antarctic petrels are compared with censuses conducted in 1983/84 and 1984/85. Population estimates varied considerably between years, and within the same year between different observers. To remedy this situation the three islands with sympatric breeding populations of the two species were divided into counting units, which are detailed with photographs. The total populations of surface-nesting petrels are in the order of 14000 pairs of fulmars, 2500 pairs of Antarctic petrel and 400 pairs of cape petrels. Chick survival was estimated at the time of banding and varied considerable between species, islands and years.
The fields in this dataset are:
Location: Filla Island, Buchan Island and Hop Island Southern Fulmar Antarctic Petrel Cape Petrel Birds Counted Estimated Pairs Population Estimates Chick survival Occupied Nests Number of Birds Conversion factor
Dataset is as complete as practicable for the 1983/84 and 1984/85 seasons. During the main period of the study (December 1983-February 1985), Antarctic petrels and southern fulmars were censused on Filla, Hop and Buchan Islands, and the southern face of McNab Island. Reference Breeding Groups (RGB's) were established by marking out roughly rectangular areas using natural feathers as boundaries where possible. One area for fulmars and Antarctic petrels was marked out on each island. The birds and occupied nests within these RGB's were accurately counted. The RGB's were counted before and after each count in the other colonies. Calculations of nesting pairs were made on the basis of the ratios within the RGB's between numbers of birds and numbers of nests. Colonies were divided into discrete units for counting, and each unit was assigned a code number. The Hop Island censuses were conducted on 13 January 1984, 10 December 1984, 2 January 1985 and 3 January 1985. The Filla Island censuses were conducted on 28 December 1983, 29 January 1984, 5 January 1985 and 6 January 1985. The Buchan Island census was conducted on 10 February 1984. The number of chicks banded in the RGB's were used as a measure of breeding success, by expressing survival as a percentage of the number of pairs known to have attempted nesting. In 1983/84 chicks of both species were banded on 15 February (Filla Island) and 23 February (Hop Island). In 1984/85 Antarctic petrel chicks were banded on 2 February (Filla and Hop Islands) and fulmar chicks on 18 February (Filla Island) and 19 February (Hop Island). Plates of the areas counted are given in the documentation. Fulmars, Antarctic petrels and cape petrels were all counted simultaneously using the same census method. Results are logically consistent. Reference Breeding Group (RGB) areas were accurately measured, and are given to the nearest 0.1m.