FACTORS GOVERNING AVIAN BREEDING IN <i>ACACIA</i> SAVANNA, PIETERMARITZBURG, PART 2: INTRINSIC FACTORS

Abstract

Summary Earlé, R. A. 1981. Factors governing avian breeding in Acacia savanna, Pietermaritzburg, Part 2: Intrinsic factors. Ostrich 52:74-83. The most important factor governing avian breeding in Acacia savanna is the body condition (protein reserve) of the bird. Breeding can take place only if the female has a large enough protein reserve to form eggs. The protein reserve is dependent on an adequate food supply which is once again dependent on climatic factors. Both the protein reserve and body weight of several species were found to be at their lowest towards the end of the breeding season. Moult and breeding were found to be largely separated in time. In most species examined testis activity was at its lowest between April and June and highest from September to January. Colius striatus showed a less seasonal pattern of testis activity while Nectarinia talatala showed very early testis activity and had fully active testes in May.