In a protected area on the southern coast of South Africa, holts (dens) of the Cape clawless otter were spaced at intervals of 470 m and spraints (faeces) were concentrated in the vicinity of the holts. Population density estimates for separate sections of coast were in close agreement, and the mean estimate for the study area was one otter per 1.9 km of coast. The minimum home range size of an adult female was 14.3 km of coast, a 7.5 km central section constituting her core area. A radio-tracked adult male had a minimum home range size of 19.5 km of coast and a centrally located 12.0 km core area. The known home ranges of four adult males overlapped completely and males were observed foraging together, indicating a clan-type of social organization.