By Matt Walker
Editor, Earth News
The new pair are given several days to get used to each other
A gibbon dating agency is helping to reintroduce once captive apes into the forests of southeast Asia.
Unusually among apes, a male and female gibbon will mate and remain faithful to one another for life, reaffirming their bond with complex mating songs.
But across southeast Asia, gibbons are captured and illegally held as pets.
Now one conservationist is returning these apes to the wild, by first rescuing them, and then using his match-making skills to pair them up.
The story of the gibbon-dating agency is told by the programme "Radio Gibbon", broadcast as part of the BBC wildlife series "Natural World".
The agency is run by Chanee Brule, a 29-year-old Frenchman who fell in love with gibbons after seeing them in a zoo as a child.
Brule runs a sanctuary in Kalimantan
He studied the apes from a young age, producing a guide to their captive care aged 13.
Today, he runs a gibbon sanctuary in a region of Borneo called Kalimantan.
At the sanctuary, Brule has broken with convention in more ways than one.
Firstly, he broadcasts a radio station from it, Radio Kalaweit, which has been dubbed "Radio Gibbon".
By playing vibrant pop music, he has acquired an active audience of young people in the region, which he also educates about ape conservation.
As a result, he receives a significant number of tip offs about gibbons that are being illegally held as pets, or have been abandoned by their owners.
Brule and his team rescue these apes, caring for them at the sanctuary.
But that is only the start of the work.
Rehabilitated gibbons cannot be returned alone into the wild, as they will be attacked by other pairs defending their territory.
Chanee Brule broadcasts 'Radio Gibbon'
So Brule attempts to pair up gibbons at the sanctuary, by match-making rescued apes.
"You can't put one male and one female in one cage and know for sure it will be a good pair," he says.
"You need to find the right character, the right gibbon with the right partner."
In particular, says Brule, one gibbon tends to dominate within each pair, and the dominant partner can be either the male or female.
"If both gibbons don't want to be dominated they will fight until one dies," he says.
So they attempt partnerships between a more dominant and less dominant character.
These pairs are then released into the forest together.
In the programme, Brule releases two siamangs together onto the island of Marak off the coast of Sumatra, where he is setting up a new sanctuary.
Gibbons are among the most endangered of all apes, living in tropical and sub-tropical forest in and around India and China, including the islands of Borneo, Java and Sumatra.
Baby gibbons are raised at the sanctuary
The belong to the small apes, which include four genera of gibbon and the siamang.
The great apes include gorillas, chimps and orangutans.
All 16 gibbon species are under threat, with 15 classed as endangered and four of them critically so.
The apes are threatened by habitat loss caused by deforestation, much to make way for palm oil plantations, and by poaching, with animals being stolen for the pet trade.
Brule's work is partly funded by the International Primate Protection League, a worldwide charity headquartered in Summerville, South Carolina, US.
"Radio Gibbon" will be broadcast on BBC Two at 2100GMT on Thursday 10 December as part of the BBC Natural World documentary series.