NOTES ON BIOLOGY AND ETHOLOGY OF NATAL ROBIN COSSYPHA NATALENSIS

A preference for bushy evergreen undergrowth determines both the local and the general distribution of Cossypha natalensis. The lack of such undergrowth makes equatorial rain‐forests unsuitable. Tropical and subtropical evergreen forests provide excellent conditions from this point of view, and they are thus the main habitat type from which C. natalensis has secondarily extended into tropical and subtropical deciduous forests with evergreen undergrowth. Adult birds remain in or close to their territories throughout the year. First‐year birds undertake longer movements during the winter. Breeding territories are relatively small, from 2,500 up to (exceptionally) 10,000 square yards (2,100‐8,400 sq. m). Breeding begins in October. Both sexes build the nest, but only the female incubates. In southern Africa there is one brood a year, and the care of the offspring is protracted. The juvenile moult begins in the third and ends in the sixth month; adults have only one (post‐breeding) moult a year. The begging behaviour of the young is somewhat different from that of most other turdine birds, and is considered to be more primitive. The ontogeny of the adult displays is described as observed in young birds kept in captivity. The development of vocal behaviour is described. Special attention is given to the different functional forms of the song, and to two of its special features, imitation and a tonal quality termed vox humana. Copyright © 1969, Wiley Blackwell. All rights reserved