Dysporus capensis, Lichtenstein, 1823, Cape of Good Hope. Monotypic.
OTHER COMMON NAMES
English: African gannet; French: Fou du Cap; German: Kaptцlpel; Spanish: Alcatraz del Cabo.
33.5–35.4 in (85–90 cm); 5.7 lb (2.6 kg). Slightly smaller than northern gannet, wings show black wingtips and secondary feathers; tail feathers also black. Black gular stripe much longer than in the other gannets; head darker cream than in northern gannet. Juveniles dark, gradually acquiring adult plumage.
Breeds coasts of South Africa and Namibia. Disperses north along African coasts, to the Gulf of Guinea in the Atlantic and to Mozambique, exceptionally to Kenya, in the Indian Ocean.
Strictly marine, mainly in waters of the continental shelf. Nests on flat offshore islands.
Much as in northern gannet although much less aggressive and site competition less intense, despite nesting in very dense colonies on flat ground. Similarly, sexual
and pairbonding displays are more moderate.
FEEDING ECOLOGY AND DIET
Feeds mostly on shoaling pelagic fish, particularly pilchard (Sardinops), anchovy (Engraulis), saury (Scomberesox) and mackerel (Scomber). Feeds by plunge-diving from 66 ft (20 m) above water. Also forms large concentrations attending trawlers.
Highly seasonal, September through April. Nests in very dense colonies on flat ground, where nests consist of accumulation of debris with central depression. Lays one egg, exceptionally two. Incubation lasts 44 days. Young fledges at 97 days. Does not start breeding until three to four years old.
Vulnerable. Only six breeding colonies known. Population has undergone important reductions in the past and, in latter part of twentieth century, has been further reduced through overexploitation of fish stocks, particularly in Namibia. Oil pollution and mortality caused by fishing gear are also known to take a heavy toll.
SIGNIFICANCE TO HUMANS
In the past, heavily exploited for food and for fish-bait. The cape gannet is one of the guano birds, its colonies being used to extract the fertilizer until well into the twentieth century.
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