It was formerly considered a subspecies of the eastern black crested gibbon (N. nasutus) from Hòa Bình and Cao Bằng provinces of Vietnam and Jingxi County in Guangxi Zhuang Autonomous Region, China.

[2] Historically, they were widespread in China: Government records dating back to the 17th century state that their range used to cover half of China,[6] although the records in question might represent multiple species, as some are from areas separated from each other by physical barriers such as large rivers that gibbons would have difficulty crossing.

The few remaining gibbons exhibit polygynous relationships; small families typically consist of one breeding male, two mature females, and their offspring.

This stable pair bond relationship seems to have allowed the gibbons to decrease their interbirth interval, the length of time between births.

[12] Their two-year interbirth interval is shorter than that of most gibbon species and coincides with the blooming patterns of fruits on the Hainan Islands.

[13] Along with offering sources of shelter and trees for singing rituals, the primary forests are also home to at least six species of plants eaten by the gibbons.

[13] When primary forests are destroyed, it takes the trees an extensive amount of time to regenerate to a state that is suitable as a home for the gibbons.

In the 1960s, much of Hainan's lowlands were deforested to make way for rubber plantations and commercial logging, causing a dramatic decline in their population.

The human population on Hainan exploded 330% between 1950 and 2003, much of which was due to the open door policy implemented by the Chinese government in the late 1980s.

[14] Naturally, the population boom led to the construction of roads and towns to accompany the developing rubber and timber industry.

[17] Therefore, the destruction of the natural vegetation on Hainan Island, coupled with the dwindling gibbon population bodes ill for the recovery of native plant species.

[2] In response to the declining population of Hainan gibbons, a collaborative status survey and conservation plan was published in 2003 and updated in 2005.

The recommendations for action focused on several factors, the first being the mitigation of habitat loss by increasing and better equipping patrols of the island to dissuade illegal loggers.

Greenpeace and FFI conservation groups have been involved in raising public awareness both locally in East Asia and abroad.