A community conservation team saw not one but two baby Cao-vit gibbons, one of the world’s rarest apes, in the remote forests of northern Vietnam in 2024, the NGO Fauna & Flora announced this month.

The first infant sighting was in February 2024 and the second in November, in two separate troops.

“It is very rare that we observe baby gibbons,” Tho Duc Nguyen, Fauna & Flora Vietnam program project manager, told Mongabay by email.

Nguyen added that female gibbons give birth to only one baby every four years or so. Across the four gibbon troops that the NGO has been continuously monitoring from 2020-2025 in Vietnam, it has only recorded one to three infants per year.

The addition of the baby spotted in November brings the total number of gibbons in that particular group to nine. “This is a sign that the number of gibbons can increase in the troop and expand the living area. Bringing a better future for the Cao Vit gibbon,” Nguyen said.

The Cao-vit or eastern black-crested gibbon (Nomascus nasutus) was believed to be possibly extinct until researchers observed a few groups in Vietnam and China in the 2000s. It’s now considered critically endangered, surviving only in a fragmented forest bordering the two countries.

Nguyen said the latest sighting of the baby was made by a Dinh Ha Duong, a member of the Cao Vit Gibbon Community Conservation Team, which includes local government staff and people from local communities who regularly monitor the gibbons. On Nov. 20, at around 7 a.m., the monitoring team heard a male gibbon start singing and moving. It was while following the troop that Duong “observed a female with an unusual way of moving and after careful observation, he discovered that this female was carrying a baby,” Nguyen said.

Tracking the gibbons is challenging, so the community conservation team uses both direct observations and new technologies such as thermal drones, thermal binoculars and an acoustic recording device called AudioMoth. After each monitoring trip, the team uploads data to the cloud so researchers can receive the information and work with the government in implementing conservation actions.

Many gibbon species are threatened with extinction due to hunting, either for the pet trade or for traditional medicine.

But since the Cao-vit gibbon’s rediscovery in Vietnam in 2002, and the setting up of the community conservation team, Fauna & Flora has not recorded any cases of the species being hunted, Nguyen said. “However, the risk of gibbon hunting is still latent, so maintaining patrols and forest protection is very important.”

The species “is protected at the highest level” of Vietnamese law, he said, adding that violations are punishable by up to 15 years in jail and 2 billion dong (about $78,000) in fines.

Banner image of a Cao-vit gibbon with an infant by Nguyen Duc Tho / Fauna & Flora