When Ancestral Statue enters the battlefield, return a nonland permanent you control to its owner's hand.
Ancestral Statue’s ability is mandatory. If Ancestral Statue is the only nonland permanent you control when its ability resolves, you must return it to its owner’s hand.
The triggered ability doesn’t target any permanent. You choose which one to return as the ability resolves. No player can respond to this choice once the ability starts resolving.