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.

Camera trapping with capture-recapture analyses has provided estimates of the abundances of elusive species over the last two decades. Closed capture-recapture models (CR) based on the recognition of individuals and incorporating natural heterogeneity in capture probabilities are considered robust tools; however, closure assumption is often questionable and the use of an Mh jackknife estimator may fail in estimations of real abundance when the heterogeneity is high and data is sparse. A novel, spatially explicit capture-recapture (SECR) approach based on the location-specific capture histories of individuals overcomes the limitations of closed models. We applied both methods on a closed population of 16 critically endangered Western Derby elands in the fenced 1,060-ha Fathala reserve, Senegal. We analyzed the data from 30 cameras operating during a 66-day sampling period deployed in two densities in grid and line arrays. We captured and identified all 16 individuals in 962 trap-days. Abundances were estimated in the programs CAPTURE (models M0, Mh and Mh Chao) and R, package secr (basic Null and Finite mixture models), and compared with the true population size. We specified 66 days as a threshold in which SECR provides an accurate estimate in all trapping designs within the 7-times divergent density from 0.004 to 0.028 camera trap/ha. Both SECR models showed uniform tendency to overestimate abundance when sampling lasted shorter with no major differences between their outputs. Unlike the closed models, SECR performed well in the line patterns, which indicates promising potential for linear sampling of properly defined habitats of non-territorial and identifiable herbivores in dense wooded savanna conditions. The CR models provided reliable estimates in the grid and we confirmed the advantage of Mh Chao estimator over Mh jackknife when data appeared sparse. We also demonstrated the pooling of trapping occasions with an increase in the capture probabilities, avoiding violation of results.

Giraffe social behaviour and relationships are currently in the period of scientific renaissance, changing the former ideas of nonexisting social bonds into understanding of complex social structures of giraffe herds. Different giraffe subspecies have been studied in the wild and only one was subject of detailed study in captivity. Our study focused on the neglected Cape giraffe (Giraffa camelopardalis giraffa). We investigated the social preferences of 28 introduced giraffes in semi-captivity in Bandia reserve, Senegal. Our aim was to assess the group size of Cape giraffes outside their native range and describe their social relationships. Mean group size in Bandia was 7.22 ± 4.06 (range 2-17). The dyads were classified according to strength of relationship (weak, medium, strong) using the association index. We reported weak and medium relationships in all types of dyads except female-juvenile. The strongest bond was found in mother-calf dyads. Three of 21 possible female dyads also demonstrated strong relationships. Those three dyads included six of seven adult females, which we labelled as friends. Females associated more frequently with calves of their friends then with calves of non-friend females. The strength of the relationship between calves depended on the strength of relationship between their mothers. We concluded that Cape giraffes in new environment have shown similar group size and nonrandom preference for conspecifics as shown in wild and captive studies. The research was supported by CIGA 20135010, CIGA 2134217, IGA FTZ 20135123, ESF/MŠMT CZ.1.07/2.3.00/30.0040.

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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.