A while ago I wrote about orangutans in Sabah (Borneo) as part of a university assignment regarding the necessity of conservation to retain any chance of the species’ (there are at least 2 of them) long-term survival.
There has been a growing awareness of the species plight, with worldwide charities such as WWF considering it special enough to be a flagship species. The species’ statuses have no doubt encouraged their conservation in recent years –a process that has knock on benefits to the entire rainforest ecosystem due to the animals being an umbrella species; however, much more work is needed.Currently, the future of these animals is highly uncertain. Predictions state that orang-utan populations have suffered a 95% reduction in recent decades, and furthermore that the resultant effects of simultaneous genetic bottlenecking are yet to be felt.
Synergic effects of hunting, habitat loss and forest fragmentation continue to threaten orang populations in both the short and long term, reducing population directly, destroying their natural habitat and inhibiting migration.
The threat of hunting is obvious; however, the threat of reduced migration may be less clear to some people. Reduced migration has resulted in pocketed populations of orangs. These smaller populations are increasingly threatened by inbreeding depression, a phenomenon in which genetic diversity is lost in populations as a result of inbreeding and stochastic effects. As has been documented in other species, animal populations can only withstand so much inbreeding before they become unviable, collapsing into extinction.
Genetic studies based on microsatellite markers have provided evidence that rivers act as natural barriers to orang-utan migration, historically leading to sub-speciation; however, human-induced deforestation has further restricted orangutan movement across rivers by destroying canopy that previously bridged riverbanks, as well as introducing additional barriers such as crop plantations, villages and roads.
In recent years however, a team of scientists has begun constructing bridges to link intact forest areas for the purpose of enhancing orang migration; refreshingly, this project has received a recent boost from Chester Zoo (1), whose staff seem to have identified the perfect material for the job. A team is now set to travel out to Borneo in October to support the current conservation scheme and, hopefully, improve the somewhat stagnant migration of Asia’s only great apes.