Contemporary and historical patterns of African penguin Spheniscus demersus: Distribution at sea

Line transects from boats were conducted during 1984 and 1985 to determine African Penguin (Speniscus demersus) distribution in the South African Cape waters. Range limits for breeding birds were derived from information on penguin travelling speeds and durations of foraging trips. Over 50% of all penguins considered to be non-breeding occurred within 20 km of the coast whilst over 50% of all breeding birds occurred within 3 km of the coast. Penguin density decreased with increasing distance offshore. The most frequently encountered penguin group size was one with larger groups decreasing in incidence according to a power curve decay. There was no difference in the frequency of occurrence of different group sizes between breeding and non-breeding penguins, nor did group size distribution change with distance offshore. Data on African Penguin distribution at sea collected in 1984 and 1985 was not discernably different to equivalent data collected between 1954 and 1974. The composition of penguin group size was also the same during both periods. © 1988.