N. cinerea was studied at the South Neptune Is. and Kangaroo I., S.A., in 1969 and 1970. This paper outlines the annual cycle and general behaviour. Sound spectrographs of several vocalizations are given. The vocalizations given by females and pups when relocating each other were very similar to those given by Arctocephalus pusillus doriferus. Pups may suckle for 2 yr prior to weaning and females were recorded suckling both a yearling and a 2-yr-old pup. N, cinerea is positively thigmotropic. Ambient temperature affects daily distribution and movements on land. They normally fear humans but local populations can develop a surprising degree of tameness. Adults commonly reach 8 or 9 yr of age.