African penguins are subject to heat stress. In hot, humid, cloudless and windless conditions; parents abandon clutches and broods for the sea to cool and prevent further dehydration. Losses to Kelp Gulls (Larus dominicanus) and other predators of eggs and chicks then frequently occur. African penguins reduce heat stress by breeding in shade (e.g. under bushes and in burrows). However, as a result of the removal of accumulated layers of guano, in which burrows can be dug, penguins have been forced to nest on the surface at many localities, increasing their susceptibility to heat stress.
Heavy rain may result in flooding of nests, drowning of small chicks and the loss of older chicks due to hypothermia.
A limited number of penguins die from entanglement in fishing nets. There is potential for this to increase if gill nets are set in proximity to breeding colonies (in South Africa, gill nets are only used in small fisheries for mullets and sharks)