Females turn back to blond at sexual maturity, keeping only a black cap on the top of their heads.

[5] This diurnal and arboreal gibbon lives in primary tropical forest, foraging for fruits, using brachiation to move through the trees.

Their songs probably serve to defend resources such as territories, food trees, partners, but may also help to attract potential mates.

[7][6] The largest known population of this species is found in Cambodia’s Keo Seima Wildlife Sanctuary, estimated at 1432 individuals in 2020.

[10] A large protected wild population can be found in Cat Tien National Park: where a collaboration with the Endangered Asian Species Trust (UK), and Pingtung Wildlife Rescue Centre (Taiwan) founded the Dao Tien Endangered Primate Species Centre, which specialises on the rescue, rehabilitation and release of N. gabriellae and other endangered primates.