Competition with Cape Fur Seals (Arctocephalus pusillus) for breeding space may be the reason for the cessation of breeding at 5 African Penguin colonies. Expanding seal herds have displaced large numbers of penguins at a number of breeding sites (e.g. Hollams Bird, Mercury, and Sinclair Islands). In addition to taking their breeding space and decreasing the availability of their food, increasing numbers of Cape Fur Seals also prey on penguins.
African Penguins also compete with other seabirds, such as gannets and cormorants for breeding space.
Predation threats to penguins are seals, gulls, cats, rats, sharks, indigenous terrestial mammalian predators, snakes and dogs.
Humans in nesting areas can disturb the penguins causing panic and desertions, thereby exposing eggs and chicks to predation by gulls. Kelp gulls and Sacred ibises prey on their eggs and chicks. Young birds may also be deterred from breeding
Collection of penguin eggs was primarily responsible for the very large decrease in numbers of African Penguins at Dassen Island between 1910 and 1956. The last sanctioned egg collections were in 1967.