Population management as a tool in the recovery of the critically endangered Western Derby eland Taurotragus derbianus in Senegal, Africa.
Wildlife Biology, 17(3) : 299-310. DOI: 10.2981/10-019.
Abstract:
The critically endangered Western Derby elandTaurotragus derbianus derbianus, representing,200 wild individuals,undoubtedly needs a coordinated conservation programme. To promote the survival of this subspecies, a singleworldwide semi-captive population was established in Senegal in 2000, with one male and five female founderstransferred from the Niokolo Koba National Park. To determine a long-term conservation strategy, we useddemographic and pedigree data based on continuous monitoring of reproduction during 2000 - 2009 in breedingenclosures in the Bandia and Fathala Reserves, in conjunction with modelling software. In 2009, the semi-captivepopulation consisted of 54 living individuals (26 males and 28 females), managed using the minimal kinship strategy.The female breeding probability was 84%, annual calf and adult mortality rates were 5.09% and 3.27%, respectively,and the annual population growth rate was 1.36. As the population grew, the animals were progressively separated intofive herds within tworeserves. A pedigree analysis revealedan effective population size of 6.72 andan Ne/N ratio of 0.13.The population retained 77% of the gene diversity (GD). The founder genome equivalent (FGE¼2.21) was relativelylow due to the overrepresentation of one founder male. Although the mean level of inbreeding (F) reached 0.119, asignificant potential GD (92%) was still retained. In this article, we predict GD development in this population in thenext 100 years with the inclusion of new founders. If the whole wild population were included, we could maintain 90%of GD. As this option is not practically feasible, we present three options with the goal of maintaining 75% GD. Wehighly recommend capturing new founders from the remaining wild population to ensure the survival of the subspeciesat least in semi-captivity, which could allow possible reinforcement of the wild population or reintroduction in thefuture. The semi-captive population, if appropriately constituted and genetically managed, could play a considerablerole in Western Derby eland conservation.
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