Robben Island, South Africa’s largest coastal island (5 × 2 km), lies 11 km from Table Bay harbour in Cape Town and 7 km from Bloubergstrand (its closest point to the mainland). The island was one of the first areas in South Africa to be colonized by European settlers, and has been extensively altered through a long history of human inhabitation, exploitation and use. The terrestrial vegetation is dominated by non-native Acacia and Myoporum and plantations of Pinus and Eucalyptus, dense stands of which cover large tracts inland.
See Box for key species. Spheniscus demersus recolonized Robben Island in 1983 after an absence of about 180 years. Numbers of penguins have increased from nine pairs in 1983 to 2,000 pairs in 1992 and to over 4,000 pairs in 1996. It is thought that birds may be relocating here from Dyer Island (IBA ZA099), where the population has decreased markedly since the mid-1980s. The breeding area was only a few square metres in 1983, but had extended to over 55 ha by 1996. The main nesting areas are under the shade of trees or bushes along the north-east sector of the island. Recently, one pair of penguins was found breeding in the south. The island also holds the largest numbers of breeding Phalacrocorax neglectus in the Western Cape and significant populations of P. coronatus, Haematopus moquini, Larus hartlaubii and Sterna bergii.
Non-bird biodiversity: Among reptiles, Bradypodion pumilum (CR) and the west-coast endemic Scelotes gronovii (LR/nt) occur on the island.
Pressure/threats to key biodiversity
The island is protected as a National Historical Monument and has been declared a World Heritage Site. This level of protection, however, is primarily for the historical and cultural value of the site. The island is famous as the location where Nelson Mandela and other political freedom-fighters were imprisoned during the years of apartheid. As a result, the island has a complex infrastructure, including many buildings. Wildlife management is yet to become a priority on the island.Competition with commercial fisheries, especially purse-seining for surface-shoaling fish such as pilchard Sardinops sagax, has been implicated as one of the most significant factors causing the global population decline of Spheniscus demersus. It is thought that penguins may be relocating to Robben Island and Boulders Bay (IBA ZA096) because of the restrictions on purse-seine fishing in Table Bay and False Bay respectively. It has been speculated that the localized protection of their food resources may allow for improved breeding success and survival. Vehicular traffic on Robben Island has been known to disturb and kill penguins.Many introduced species occur on Robben Island, including 38 exotic plants that have considerably modified the island and occupied a large proportion of it. Many introduced mammals also occur here, including Rattus rattus and Felis catus, which prey on bird eggs and young fledglings.Owing to its status as a monument, the island is open to tourism, and it is expected that visitor numbers will increase substantially in the next few years. Management options need to be carefully considered in order to direct tourism activities away from sensitive seabird areas. It is expected that with the establishment of the monument, uncontrolled and unmitigated disturbance in the most sensitive areas will be reduced, and many breeding seabirds will return.An unpredictable threat, which is difficult to control, is chronic pollution by crude oil or other pollutants, which spill into the ocean when tankers break open, wash their tanks, dump cargo or pump bilge. Spheniscus demersus is particularly susceptible to these events and a single oil disaster can severely affect populations. The South African National Foundation for the Conservation of Coastal Birds (ZANCCOB) cleaned, rehabilitated and returned some 3,000 penguins to the wild between 1981 and 1991. Most penguins rehabilitated at the South African National Foundation for the Conservation of Coastal Birds (ZANCCOB) are released on Robben Island, from where they return to their breeding colonies.