Cape gannet  (Morus capensis)

With breeding restricted to just six small islands, the Cape gannet is considered vulnerable due to over-exploitation of its prey by human fisheries, pollution, and human disturbance (2). Food shortages, following the collapse of the Namibian sardine fishery, have been the main cause of the 85 to 98% decline in numbers seen at the three Namibian colonies over the past 50 years (1956 - 2006) (2) (9). By contrast, increases were seen at all three South African colonies during this time, until December 2005, when attacks by Cape fur seals (Arctocephalus pusillus) on birds at nests at Lambert's Bay caused abandonment of the entire 20,000-strong colony (9) (10). Oil spills are also a significant threat, with around 5,000 Cape gannets found oiled during an incident in 1993 (2). Additionally, although information of other pollutants affecting Cape gannets has been scarce, traces of DDE, DDT, Dieldrin and PBC's have been found on eggs (4). Guano was collected at all Cape gannet colonies to be utilised for fertiliser, and may have decreased breeding success through inhibiting some birds from laying and reducing the effective breeding season (2) (4) (8). Mortality of Cape gannets occurs from drowning in long-line fisheries (7).

All breeding colonies of the Cape gannet are under some form of protection (4). In South Africa, all colonies are under the administration of CapeNature Conservation (Bird Island, Lambert's Bay) or South African National Parks (Malgas Island; Bird Island, Port Elizabeth) (2) (4) (8). In Namibia, the three breeding islands are administered by the Ministry of Fisheries and Marine Resources. All six islands have been identified as Important Bird Areas (IBAs) (2) and public access is restricted, with the exceptions of Bird Island (Lambert's Bay), where visitors are able to view the colony from state-of-the-art observation facilities, and Malgas Island, to which guided tours organised by the West Coast National Park are available (4). Oiled birds are rehabilitated at the South African National Foundation for the Conservation of Coastal Birds (SANCCOB) (4), and the species is protected by law (2).

Following the colony's abandonment of Bird Island, Lambert's Bay, in December 2005, and the consequent collapse of a profitable bird-watching industry there, an ingenious plan to entice the birds back was quickly formed. Duck hunters have long known that carved wooden ducks floating on the water will attract the real thing, so a similar tactic was employed using life-sized gannet ‘decoys' to tempt the real birds back. These fake birds were deployed on the deserted nests early in July 2006 after the provincial nature conservation authority, CapeNature, had appointed an island manager, Yves Chesselet, who is working on plans to protect the gannets from the seals. The initiative has been a fantastic conservation success story, with gannets starting to land within an hour of putting out the decoys, and nearly 10,000 having returned by mid-August (10). A largely successful programme to discourage seals on Mercury Island could perhaps now be employed to similar effect on Bird Island (2).