Between 1900 and 1930, millions of eggs were collected for human food. Collectors would enter the nesting areas and remove all the eggs, wait for fresh eggs to be laid, and remove those too. This practice has been banned.
Over centuries the guano (penguin poop) on the islands formed thick layers, sometime metres thick. The penguins would burrow into the guano and use the burrows as safe, well insulated nest sites. People collected tonnes of the guano off the islands to use as fertilizer. The result is that the penguin nests were left vulnerable to the elements and predators.
Threats include competition with commercial fisheries for pelagic fish prey.
Large spills are catastrophic for the penguins. Not only are the individuals affected, there is also the disturbance to their breeding cycles. Small spills from boat bilge cleaning can also cause problems.
There is a lack of suitable nesting sites for penguins, close to their foraging sites. Primarily sub-adult male Cape Fur Seals kill and eat penguins. Feral cats on islands and the mainland can pose a problem. African Penguins also face predation of eggs and chicks by avian predators such as Kelp Gulls, while natural terrestrial predators, such as mongooses, caracal, snakes and jackals occur near the mainland colonies.