Conservation programme of Western Derby eland: Is there any hierarchy in mixed herds of this critically endangered antelope?
Pavla Jůnková Vymyslická
Czech University Of Life Sciences Prague
Pavla Jůnková Vymyslická, Karolína Brandlová, Pavla Hejcmanová, Magdalena Žáčková, Kateřina Hozdecká
Introduction: What conservation problem or question does your study address?
Western Derby eland (Taurotragus derbianus derbianus) is a critically endangered antelope species surviving in very low numbers (170 individuals in the wild) only in Senegal. Because of low numbers of this species their survival depends on management decisions, but very little is known about their behaviour. We analysed the social dominance of mixed herds of this species in semi-captive conditions, in Bandia reserve, Senegal.
Methods: What were the main research methods you used?
The study was conducted in Bandia reserve, Senegal, where two breeding mixed herds (H1, H2, n=13, 22, 22, 24) were observed during 2006, 2010, and 2011. Ad libitum sampling method of dyadic interactions was based on dominance/submissive displays between two animals. The matrix tabulation was used to record the outcomes of agonistic interactions between pairs. The most suitable index for hierarchy measuring was selected the Frequency-based dominance index (FDI), where the number of inconsistencies was the lowest. Landau’s index of linearity (h) was used to determine the linearity in the herd. Because the data did not have the normal distribution we used the nonparametric tests and analysed them in STATISTICA package to find out whether the social rank is affected by age, sex, or age-sex category and whether there is a relationship between the rank of offspring and the rank of its mother.
Results: What are your most important results?
The study revealed linear hierarchy in all herds. Hierarchical rank was significantly related to age in both herds in all observed years but no effect of sex was revealed except of H1 in 2006 where some tendency of effect of sex on the rank was visible (P = 0.053). Influence of age-sex categories was significant, but no difference was revealed between males and females in respective age category. Correlation between rank of offspring and rank of its mother was not proven.
Discussion: What are your important discussion points and what is the relevance of your results to conservation (if any)?
According to results gained on similar species we expected complex hierarchy with effect of age and sex on the rank. Detection of linear hierarchies in mixed herds of Western Derby eland in semi-captive condition can be used as a management tool for manipulation of animals or to facilitate the treatment of diseases through oral served medicaments without the need of financially and logistically demanding immobilization.