Study at Jutten Island, Saldanha. Current name: African Penguin. The effects of human passage through low-density colonies of breeding jackass peguins Spheniscus demersus, and of human approach to high-density colonies were assessed. Passage disturbance led to egg loss through predation by kelp gulls Larus dominicanus and invariably frightened nest prospecting penguins away from the colony after the third or fourth intrusion, regardless of the interval between intrusions. Birds were disturbed and occasionally left the colony when an observer was less than 30 m from the edge of a high-density colony. Adult birds reacted most to a slow, direct approach and chicks to a staggered approach. The exodus rate of birds was higher at coastal than inland colonies, where no exodus was recorded. Results are discussed in relation to the conservation of the jackass penguin. This paper constitutes part of the commemoration of the 21st anniversary of the establishment of the Percy Fitzpatrick Institute of African Ornithology.