A mother gibbon with her baby in the forests of Vietnam.
An adult male northern white-cheeked gibbon (Nomascus leucogenys) found in northern Vietnam and Laos. The species is listed as endangered.
The yellow-cheeked gibbon (Nomascus gabriellae) is critically endangered and known from Vietnam and Cambodia.
In 2008, scientists with the Wildlife Conservation Society counted 2,500 yellow-cheeked crested gibbons in Cambodia's Seima Biodiversity Conservation Area, which is about the size of Yosemite National Park.
A southern white-cheeked gibbon (Nomascus siki) at the Endangered Primate Rescue Center, Cuc Phoung National Park, Vietnam.
A baby gibbon learns the art of tree swinging.
Crested gibbons like this one face risks from human activity, including habitat loss and hunting for pet trade.