Are the Chao an endangered species now? We don't see very many of them anymore.
The Chao require very clean and pure water in order to survive, so you may not see them in a lot of places. If you do go to Rio de Janeiro in Mario & Sonic at the Rio 2016 Olympic Games, you'll probably see a lot of them in the stands.

That question was made by game informer, last year. Well, as far as I know Rio de Janeiro bays, well all chao are dead right now, because those waters are everything but pure. RIP Chao...

Soucer: Game informer