Title: Trends of African penguin<i>Spheniscus demersus</i>populations in the 20th century
Abstract: The entire nesting population of African penguins Spheniscus demersus was about 575 000 adults at the start of the 20th century. Numbers halved by the 1950s and continued to fall to about 220 000 by the late 1970s and about 180 000 by the early 1990s. In Namibia, there has been a 30% reduction since the late 1970s, the most severe declines being in the south, where colonies continue to decrease. Populations at Mercury, lchaboe and Halifax islands now appear to be stable. In South Africa, numbers fell by 17% between the late 1970s and early 1990s, with especially severe decreases near Saldanha Bay and at Dassen and Dyer islands. These decreases have been arrested, except at Dyer Island. Three new colonies were established in the Western Cape in the early 1980s and supported about 10 000 adult birds in 1994. At islands in Algoa Bay, numbers of adults increased by nearly 30 000 between the late 1970s and the early 1990s, with large increases at St Croix and Bird islands. Ongoing deterioration in the status of the species is being driven by the trends at Dyer Island and off southern Namibia, the causes of which must be investigated.