Tsou (3497-tsu) = Endangered (100 percent certain, based on the evidence available) (Children also learn the basics, but their language competence is far from the elderly native speakers. Young people in general have at least the passive knowledge of their heritage language.)
Glottolog
[tsu] at ISO 639-3
[tsu] at OLAC
[tsu] at IMTVault
Tsou at Endangered Languages Project
Tsou at Grambank
Tsou at WALS
Wikipedia
PHOIBLE
Wikidata