One of the largest of antelopes, Derby eland (Taurotragus derbianus), is an important ecosystem component of African savannah. While the western subspecies is Critically Endangered, the eastern subspecies is classified as least concern. Our study presents the first investigation of population dynamics of the Derby eland in the Chinko/Mbari Drainage Basin, Central African Republic, and assesses the conservation role of this population. We analysed data from 63 camera traps installed in 2012. The number of individuals captured within a single camera event ranged from one to 41. Herds were mostly mixed by age and sex, mean group size was 5.61, larger during the dry season. Adult (AD) males constituted only 20% of solitary individuals. The overall sex ratio (M:F) was 1:1.33, while the AD sex ratio shifted to 1:1.52, reflecting selective hunting pressure. Mean density ranged from 0.04 to 0.16 individuals/km 2 , giving an estimated population size of 445-1,760 individuals. Chinko harbours one of the largest documented populations of Derby eland in Central Africa, making Chinko one of its potential conservation hotspots. R esum eUne des plus grandes antilopes, l' eland de Derby (Taurotragus derbianus) est une composante importante de l' ecosyst eme de savane africaine. Alors que la sous-esp ece de l'Ouest est "En danger critique d'extinction", la sous-esp ece de l'Est est class ee comme "Pr eoccupation mineure". Notre etude pr esente la premi ere enquête sur la dynamique de la population de l' eland de Derby dans le bassin de drainage de Chinko/Mbari, en R epublique Centrafricaine, et elle evalue le rôle de cette population pour la conservation. Nous avons analys e les donn ees provenant de 63 pi eges photographiques install es en 2012. Le nombre d'individus captur es par une seule cam era allait de 1 a 41. Les troupeaux etaient en g en eral m elang es quel que soit l'âge et le sexe, et la taille moyenne d'un groupe etait de 5.61 individus, plus grand en saison s eche. Les mâles adultes ne repr esentaient que 20% des animaux solitaires. Le sexratio global (M/F) etait de 1/1.33, alors que le sex-ratio des adultes passait a 1/1.52, refl etant l'impact de la pression s elective de la chasse. La densit e moyenne allait de 0.04 a 0.16 individu/km², ce qui donne une population estim ee entre 445 et 1,760 individus. Chinko accueille une des plus grandes populations d' elands de Derby connues en Afrique centrale, ce qui en fait un des hauts lieux potentiels de leur conservation.

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Wild giraffes live in extensive groups in the fission fusion system, maintaining long social distances and loose social bonds. Within these groups, resources are widely distributed, agonistic encounters are scarce and the dominance hierarchy was reported in males only, while never deeply analysed. In captivity, the possibility to maintain inter-individual distances is limited and part of the resources is not evenly distributed. Consequently, we suggest that agonistic encounters should be more frequent, leading to the establishment of the dominance hierarchy. Based on the differences in resource-holding potential, we suggested that the rank of an individual would be affected by age and sex. Based on hypotheses of prior ownership, we tested whether rank was positively affected by the time spent in a herd and whether it was stable in adult females, which were present long-term in the same herd. We originally monitored four herds of Rothschild giraffes (Giraffa camelopardalis rothschildii) in Dvůr Králové zoo (n = 8), Liberec zoo (n = 6), and two herds in Prague zoo: Prague 1 (n = 8) and Prague 2 (n = 9). The Prague 1 and Prague 2 herds were then combined and the resulting fifth herd was observed over three consecutive years (2009, 2010, and 2011) (n = 14, 13, and 14, respectively). We revealed a significantly linear hierarchy in Dvůr Králové, Prague 2 and in the combined herd in Prague. Rank was significantly affected by age in all herds; older individuals dominated the younger ones. In females, rank was positively affected by the time spent in the herd and adult females in Prague maintained their rank during three consecutive years. This study represents the first analysis of the dominance hierarchy in the captive giraffe, and discusses the behavioural flexibility of the social structure in response to monopolisable resources in a captive environment.

No abstract

Nursing behaviour is one component of mammalian life history strategy that demonstrates context-dependent flexibility within species. Wild giraffes live in groups and feed themselves over large area. In the zoo, giraffes are kept in enclosures with abundant food resources. We aimed to analyse whether the nursing behaviour of giraffes differs between the zoo and nature reserve and discuss which factor (food intake, presence of predators, population density) can explain the difference. We observed seven and four female–calf pairs in the Bandia reserve, Senegal, and in Prague Zoo, Czech Republic, respectively. Nursing bouts were less frequent and longer and calves were less successful in nursing solicitations in the reserve, as females there seemed to be more selective for nursing times and locations, likely due to presence of predators and differences in food intake. Allonursing occurred more frequently in the zoo which can be attributed to higher population density in captive conditions.