These arboreal lesser apes evolved for life in the trees. But when people cut those trees down the gibbons had nowhere left to go.

Species name: Northern white-cheeked gibbon (Nomascus leucogenys). The northern and southern (N. siki) gibbons were only recognized as separate species a few years ago.

Where found: Very small regions of Vietnam, Lao and (maybe) China, although it hasn't been seen in that country since 1990. The only known viable population—130 groups totaling about 455 gibbons—was discovered just two years ago and lives in a single park in Vietnam.

IUCN Red List status: Critically endangered. The total population count for this species is unknown.

Major threats: Deforestation for agriculture and logging, as well as poaching for food (sadly, logging roads have made it easier for people to reach forests and hunt the animals). The remaining populations for this species are highly fragmented and small, with few opportunities to travel and broaden their gene pools.

Notable conservation programs: Several zoos are breeding northern white-cheeked gibbons, one of just three gibbon species actively being bred under the Gibbon Species Survival Plan Program of the Association of Zoos and Aquariums. The cooperative breeding program has had several successes lately, and in fact the Gibbon Conservation Center in California announced the birth of a young gibbon just a few days ago. In addition Conservation International has been active in Vietnam and Lao and discovered the big population in Pu Mat National Park two years ago. Meanwhile the Gibbon Conservation Alliance in Switzerland does great work helping to preserve all gibbon species.

Multimedia: Listen to the northern white-crested gibbons' beautiful, undulating vocalizations here.

Lincoln Park Zoo welcomed a baby white-cheeked gibbon this past August. Check out the happy mother below:

Photo: A white-cheeked gibbon mother with her newborn at Adelaide Zoo in 2011. By Roger Smith via Flickr. Used under Creative Commons license