The northern white-cheeked crested gibbon is running out of places to live in – literally. Perhaps the only habitat they can still find in the whole world is located deep in the wilderness of Vietnam, according to Conservation International. The organization conducted a census, and found that the biggest population by far is located there, numbering 450 individuals.

The species is already technically extinct in China, and the numbers in Laos and other countries have gone down dramatically in the past years. This is but one of the 25 species of gibbons, all of which are endangered with some drawing extremely close to the brink of extinction. However, things are even worse than they would seem.

A species needs more than just barely survive; they need numbers which can account for genetic variety, otherwise, they will not be able to survive any other treats, be they natural or anthropic.

The white-cheeked gibbons are especially an interesting species. They are monogamous, and have been described as the most romantic primate species, because during the mating period, they sing to each other. They are also mostly vegetarian, and they rarely even touch the ground, jumping around from tree to tree.