(Image source: Terry Whittaker)

BY: TRACY PFEIFFER

ANCHOR: ANA COMPAIN-ROMERO

Researchers in Vietnam have located what they believe is the only viable population of northern white-cheeked crested gibbons.

The discovery came -- not from seeing the creatures -- but from hearing them.

Gibbons are known for their distinct calls - and so researchers from Conservation International found the 455-member population through the use of “listening posts.”

The regional primate expert Ben Rawson explains. (Audio: ABC Radio)

BEN RAWSON: “...in terms of doing the survey, the population surveys, what we do is we just sit there and we listen for gibbons and we take compass bearings to the locations where they are or where we think the vocalisations are coming from, and if you have multiple listeners in an area you can actually triangulate the locations of where these gibbons are calling from.”(ABC Radio)

The population was discovered in Vietnam’s Pu Mat National Park.

While once common in the areas of Laos, China, and Vietnam, Rawson estimates there are only ten wild gibbons left in the Chinese wilderness today.

“The northern white-cheeked crested gibbon belongs to the crested gibbon family, which has been dubbed the most endangered primate family in the world. There are eight known species of crested gibbon, seven of these are either listed as Endangered or Critically Endangered. The eighth was only discovered last year and has not yet been evaluated, but researchers believe it is likely to be threatened as well.” (Mongabay.com)

The International Business Times reports -- the gibbons have apparently thrived because of their location -- but that may not last much longer.

“The new population was found in a remote, dense forest, at high altitudes on the Vietnam-Laos border, where they have been isolated from human populations... But road development in this area is posing a serious threat to the gibbon's future because this group thrived because of the remoteness of the habitat.”

This particular species is also known as the quote- “most romantic” of the gibbons because of their so-called “boisterous” mating rituals -- to win over their lifetime partners. 

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Transcript by Newsy.