Ross Sea Emperor Penguin Breeding Populations Estimated by Aerial Photography

Summary

In December 1983 aerial photographs of all emperor penguin breeding colonies along the Ross Sea coast from Cape Roget south to Beaufort Island were taken for the purpose of censusing this species. Cape Crozier, the most southerly colony, was counted from the ground. Chicks and adults could not be distinguished from the photographs. They were differentiated by using chick: adult ratios of 7 chicks to 1 adult (± 2.14 standard deviation, n = 11) obtained from ground counts on 12 to 14 December 1986 at Cape Washington. Of the six colonies, the smallest was Cape Crozier (78 chicks) and the largest was Coulman Island (estimated 22 137 chicks). Except for Cape Crozier and Beaufort Island, for which the most recent published censuses were in 1977, the other colonies had not been counted since their first and last census in 1968 or earlier. There are differences between some of the earlier and the 1983 censuses. The estimated total of breeding birds in 1983 was about 120 000. A common characteristic of all colonies within the Ross Sea is their proximity to open water.