A modified photogrammetric technique for assessing age-structures of elephant populations and its use in Kidepo National Park

(1) A modification of an aerial photographic technique for assessing the age-structure of African elephant populations is introduced. (2) The method is quick, inexpensive, and provides important population dynamics information relevant to one of the most serious wildlife management problems in Africa–namely, the interaction of elephants and their habitats. (3) The method consists of photographing elephant breeding herd groups vertically, measuring their relative lengths, and then relating the lengths to a mean breeding herd growth-curve. (4) An example of the application of the technique is given in an assessment of the age-structure of two elephant populations in the Kidepo Valley National Park, Uganda. (5) The Kidepo populations are similar in age-structure and are in general healthy. The similarities probably represent allopatric responses to the same climatic regime. (6) Peaks and troughs in the age-structures are related to local rainfall, which indirectly aifects conception and mortality of young animals. (7) There are some obvious differences between the two populations, the home-ranges of which exhibit differences in rainfall and habitat characteristics. The differences between the populations reaffirm the sensitivity of elephant population regulating mechanisms to local variations in climate and rainfall. (8) The relative roles of post-mortem and observational techniques in elephant studies and the need for long-term research are discussed.