Ex situ gibbon conservation: Status, management and birth sex ratios

Many zoos take part in captive-management programmes for gibbon species, which contribute to the conservation of this highly threatened taxon. Eight gibbon species are represented in captive-management programmes glob- ally, although the numbers held are highly biased towards only two species, which fill most ofthe space available in zoos. The other gibbon species are held in small popula- tions that are difficult to manage and, thus, are unlikely in their current form to be self-sustaining. Effort and, more importantly, space are required to grow these small gibbon populations. In addition, the space that is avail- able needs to be used wisely. This may require that only animals that can actively contribute, whether genetically or socially, to the goal of achieving a self-sustaining captive population are maintained. There is also a need to investigate the impact ofenvironmental factors in captiv- ity as they relate to birth and death rates, which would enable evidence-based captive management of gibbons with the aim of stimulating breeding and mitigating the potential deleterious impacts associated with managing small populations.