Over 4,300 species in Southeast Asia are at risk of extinction due to habitat loss, climate change, and wildlife trafficking. Critically endangered species like rhinos and langurs are on the brink.

The Javan and Sumatran rhinos are down to their last few dozen, just like the Cat Ba langur of Vietnam, while the soala living in Laos’ Annamite mountains may already be gone for good. Southeast Asia’s remarkable biodiversity is under severe threat from the encroachment of cities and farms, deforestation, warming seas and the trafficking of rare wildlife for food, traditional medicines and as pets. The International Union for Conservation of Nature (IUCN) told This Week in Asia that more than...