Former multiple cat owner here, every cat I have owned hunted successfully with multiple bells on their collars. My neighbours cat has bells and hunts in my yard. Bells don't work or don't work reliably enough.

The chipmunks around my house are dumb af. They get scared of the cat, but after 2 minutes of sitting still they're running right by him again. It's almost like they evolved to be food.

Bells don't work. Cats are more than comfortable staying still enough to keep them silent.

Additionally, bells don't impact the other damage outdoors cats do to gardens, the deceased life expectancy, and the increased chance of disease.

Do not let your cats outside.

> Bells don't work. Cats are more than comfortable staying still enough to keep them silent.

Saw this with the neighbours cat, little sod is so smooth he doesn't ring the bell until he pounces and by then the bird already knows it's in deep shit.

My pair are indoor cats - they live longer and we are near a very busy road.

"Those humans are nasty, now every time I hear a loud bell it means one of my friends has died"

- local bird, probably

One might think so, but I saw a neighbor's declawed bell-laden cat routinely catch prey. The bell surely didn't help the cat, but the birds, mice, shrews, snakes, etc. needed more than a bell to save them.