In lush, tropical forests, males and female gibbons mark their territory in the trees by singing different parts of a noisy chorus. Sadly though, their songs are hard to come by, as the apes are fighting to survive.

Here’s what they’re up against: Gibbons’ habitats - mostly in southern and Southeast Asia’s tropical rain forests - are dwindling. They’re being hunted and poached. They’re also being captured alive to keep in zoos and as pets. Each year, accelerating numbers of gibbons are caged, collared, or leashed as part of the world’s wildlife trade.

But it’s crucial that gibbons live in their natural homes instead of in ours. Primates have a direct impact on the health of their surrounding ecosystems. While dispersing seeds and interacting with their environments, primates help support a wide range of plant and animal life that makes up the Earth’s forests.

Still, gibbons are prevalent in the wildlife trade. A 2005 report published by the wildlife monitoring network TRAFFIC revealed that 559 gibbons and orangutans were on sale or illegally traded in 35 Indonesian wildlife markets between 1994 and 2003 - despite the fact that Indonesian law prohibits selling, capturing, possessing or killing them. If punished for the crime, they’d face more than $10,000 in fines and five years in prison. Yet people still traffic in these important species because there’s little enforcement to hold them accountable.

This year, two gibbon sub-species are included on a list of the world’s 25 most endangered primates, compiled annually by the Primate Specialist Group of IUCN’s Species Survival Commission and the International Primatological Society, in collaboration with Conservation International (CI). The Western Hoolock gibbon (Bunopithecus hoolock hoolock), found in Bangladesh, India, and Myanmar, graces that list, as does China’s Hainan black-crested gibbon (Nomascus hainanus), which today numbers less than two dozen.

Together, we can take action to better protect gibbons and the rest of the world’s primates from the wildlife trade and other threats. Here’s how: