22 August 2011 Last updated at 11:25

Chester Zoo team to build orangutan bridges in Borneo

By Victoria Gill Science reporter, BBC Nature

Bornean orangutans cannot swim, so the bridges should help them move around

A team from Chester Zoo will join conservationists in Malaysian Borneo later this year to help construct special "orangutan bridges".

The structures are designed to allow the animals to move around in an area that has become fragmented by deforestation.

They will incorporate materials the zoo uses in its orangutan enclosure.

Marc Ancrenaz, co-founder of the Kinabatangan Orang-utan Conservation Project, is leading the venture.

Chester Zoo's Nick Davis explained: "When Marc came to the zoo, he noticed that we had this webbing material that we used for our enclosure

Dr Davis, who will take part in the Borneo expedition said that, for orangutans, "we're limited in the materials we can use, because they destroy everything".

The tough polyester webbing material that the zoo uses to make swings and hammocks in its enclosure, appear to be "orangutan-proof".

"It's a very strong material that's used for strapping," said Dr Davis. "And it's really hardy so it doesn't rot."

Fragmented forest

Mr Ancrenaz is a wildlife vet based at a field station in a village called Sukau, He and his colleagues have been building the bridges for the last five years.

They undertook the project after studies showed that the local orangutan population had been fragmented into 20 sub-populations isolated from each other by vast tracts of palm oil plantations, roads, villages, and rivers.

Unlike many other primate species, orangutans cannot swim, so as well as the river being an impassable barrier, logging activities have disrupted the tree canopy above smaller river tributaries, making these impossible to cross.

Dr Davis told BBC Nature: "[The aim of the bridges] is to cover the drainage channels and tributaries that come from the palm oil plantations."

The team will head to Borneo in October and hope to support the work in the region in the long-term.

"This is just a first stage - we're going to try different designs," said Dr Davis.

"The worry is that the forest out there has been so fragmented that the orangutans can't move around at all."