I guess the odd deaf squirrel wasn’t likely to last long anyway. A bell could work to keep them from stalking. They can still run, leap, and ambush. It seems a bell should at least greatly mitigate the issue. I might say usually rather than always. To be fair, though, supervision won’t stop them every time either.

> They can still run, leap, and ambush.

Whenever they do, there is a little tingle tingle, whatever tiny little movement they're trying to do. They end up unable to catch anything basically, I literally never witnessed one of our cats catching anything growing up, nor them bringing any "gifts".