Gibbons are somewhat overlooked or at least undervalued. When referenced, people consider a generic gibbon, which usually includes recognition of their unique anatomy and use of brachiation, sophisticated communication and singing bouts, but does not do justice to the most species-rich group of apes (see Thomas Geissmann's Gibbon Research Lab. at http://www.gibbons.de). There are 16 gibbon species in four genera (Hylobates, Hoolock, Nomascus and Symphalangus) occupying several countries in South East Asia; more recently data have been published proposing recognition of a further gibbon species, the Northern buffed-cheeked gibbon Nomascus annamensis (Thinh et al., 2010). Maybe it is because the gibbons’ closest relatives are our closest relatives – the great apes – or that taxonomic and individual identification can be challenging, or maybe it is because they were originally labelled ‘lesser’ rather than ‘great’ apes? It is true gibbons are little but they are not lesser. Many of these small apes have a key role in the ecology of their habitats, the conservation of which is desperately overdue.
It is likely that the first gibbon extinction has already occurred. Surveys in China continue but fail to find Hylobates lar yunnanensis, which is now thought extinct (Geissmann, 2008). Four Nomascus species are Critically Endangered, the other two Endangered (IUCN, 2011). The most infamous being the Hainan gibbon Nomascus hainanus numbering about 20 individuals in one location (Mootnick et al., 2012) they have the unenvied title of being the world's rarest primate. As the most endangered Nomascus species are not held or managed in global captive management programmes (Melfi, 2012) their future survival rests on in situ conservation efforts. These efforts include the activities undertaken by sanctuaries throughout South East Asia, which house many gibbons. Cheyne et al. (2012) summarize a variety of the issues encountered by sanctuaries when housing and rehabilitating gibbons. They provide a working framework and call for more scientific rigour to enable sanctuaries and their activities to become more evidence based and open to objective scrutiny. An example of how good science can be used to underpin integrated conservation work in a sanctuary is provided by Kenyon et al. (2012).
Using vocalization survey data techniques a population of about 450 Northern white-cheeked gibbons Nomascus leucogenys has recently been recorded in Vietnam (Luu Tuong Bach & Rawson, 2011). It is thought that this small population has more than doubled previous population estimations for this species in Vietnam. Although the trend is that populations of all gibbon species are facing devastating declines, there is still hope, all the time we have animals and a commitment to integrated evidence-based conservation. With so many species and their habitats at risk of extinction, my desire is that the four papers in this Gibbon Conservation subsection will highlight ‘why gibbons’ and ‘why now’.