Common Eland (Tragelaphus oryx) Population Trends in the Ukhahlamba-Drakensberg Park and Surrounds, South Africa, between 1942 and 2018

Abstract

Management of protected areas requires an understanding of the long-term population trends of large mammal species that may influence ecosystem functioning. Common eland (Tragelaphus oryx) are the most abundant large mammal species in the uKhahlamba-Drakensberg Park. Aerial and ground surveys have been conducted over the years to monitor the common eland population. This study addressed long-term trends in population size, structure, distribution and mortality of the common eland between 1942 and 2018, examining changes in relation to climate, natural impacts, management, and efficacy of surveys. The common eland population in the Drakensberg remained relatively stable from 1942 to 1982, then increased between 1983 and 1990. However, a continuous decline was observed between 2003 and 2018 concomitant with a 37% reduction in distribution range within the Park. Adults constituted 59.4% of the population over the entire period, while subadults and calves accounted for 19.1% and 18.8%, respectively, with the remaining 2.7% of unknown ages. The ratio of adults: subadults: calves was 1: 0.32: 0.32 and males: females was 1: 3.63, indicating a skewed sex ratio and a low number of juveniles in the population. Human activities had a substantial impact on the population, with 30.3% of mortalities attributed to poaching. However, permitted offtakes of an unknown number may be the most important cause of mortality. Increased movement of eland onto farmlands outside of the protected area appears to have contributed to a decline in their distribution within the Park in recent years; however, this does not affect population trend since those on farmland are still included in counts. There is no cause for concern regarding the population trend at present; however, if the observed population decline continues well beyond the population numbers recorded in 1942, then there is cause for a management response by Ezemvelo KwaZulu-Natal Wildlife for the common eland population in the Drakensberg.