Age-sex structure of drought-driven African elephant (Loxodonta africana) mortality in Hwange National Park, Zimbabwe

Abstract

Age and sex determination of 101 lower jaws from drought-driven savanna elephant mortalities was done in Hwange National Park (HNP) using the Age Reference Line (ARL) method. We recorded an overall higher number of female elephant death compared to males. The age at death was skewed towards the young and very old individuals, with an overall gradual decrease in frequency into prime cohorts. Female elephant mortalities were more prevalent in young animals, nursing, and very old individuals. A similar mortality trend was observed for male elephants below the age of 22 years. We did not record any elephant between the age of 45–52.5 years for both sexes. We support the notion that the overall distribution of the female's mortality prevalence compared to males is aligned to and influenced by the social and developmental behaviour of savanna elephants. Our findings suggest a natural selection process at play, facilitated by resource limitation during the period of drought. This study provides evidence for the need to get back to the basic ecological principles and understanding of natural ecological processes in the conservation of key species. Although elephant mortalities due to drought represent a small proportion of the entire population in the study area, more work needs to be done to investigate the influence of drought, novel infections and anthropogenic drivers as they have potential to affect savanna elephant populations in the long term.