Demographic changes in the Luangwa Valley elephants

A ground level survey of elephants in the Luangwa Valley, Zambia, revealed an altered population for characteristics measured approximately 10 years earlier by other investigators. Frequencies of new-borns, yearlings, and two-year-olds relative to adult females were nearly half the values reported a decade earlier. This apparent drop in calving rate could not be attributed to rainfall. Other factors, including stress from poaching, are discussed. Adult sex ratio favoured females by 2·5 to 1, which departs strikingly from the near-even sex ratio reported earlier. The possible relationship between a skewed sex ratio and reproductive success for this population is discussed.