Hainan black-crested gibbons, listed as the world's most endangered primate species, are found only in Hainan Tropical Rainforest National Park. 

To preserve the tropical rainforest ecosystem, residents in the core area moved out to leave an undisturbed environment for ecological restoration. The national park has researched the species and overseen regulations to conserve and rehabilitate the habitat of Hainan gibbons and other unique, rare wildlife species.