Aspects of reproduction in the African elephant in the Luangwa Valley in Zambia were studied in relation to the population dynamics of the species. The fetal and the secondary sex ratio up to 16 years of age did not depart significantly from equality. Males left family units soon after 16 years of age and joined bachelor herds. From 1964 to 1968, 88% of conceptions were in the rains, but in 1969 there was a shift in the breeding season peak to the dry months of the year. There was no evidence of seasonal breeding in the male elephant. Females reached maturity at 14 years, and males at 15 years, when the combined weights of the testes reached 650 to 700 g, and the mean seminiferous tubule diameter reached 90 to 120 μm. The mean calving interval was 3·5 to 4·0 years. In the population, 6% of the elephant were less than 1 year old. Apparent cycles of recruitment were considered to be artefacts caused by slight inaccuracies of the ageing technique used. Corpora albicantia accumulated at the approximate mean rate of 0·6/year, and the significance of this was examined in relation to comparative studies of population fertility. Reproductive senescence was a consequence of a combination of uterine defects and a reduction of oocyte number.
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