Traditional ecological knowledge (TEK), an important component of the modern conservation toolkit, is being eroded in indigenous communities around the world. However, the dynamics of TEK loss in response to ecosystem change and disruption to social-ecological systems, and patterns of variation in vulnerability and resilience of different components of TEK, remain poorly understood. The Hainan gibbon (Nomascus hainanus), a culturally significant primate, was formerly distributed across Hainan Island, China, but became extinct across most of this range within living memory and is now restricted to a single landscape, Bawangling National Nature Reserve. Gibbon-specific TEK (including folktales, natural history information and methods of gibbon exploitation) is still present in indigenous communities across seven Hainanese landscapes, but statistically significant differences in TEK content exist between landscapes with different histories of gibbon persistence: respondents from Bawangling and most landscapes that have recently lost gibbons report more gibbon-related folktales compared with landscapes from which gibbons have been absent for several decades. Species-specific folktales might have been lost more rapidly compared with other components of TEK because older community members are typically the 'cultural repositories' of stories, whereas knowledge about practical interactions with biodiversity might be shared more widely with younger community members.