Siberian cat Numi sadly specialized in catching bats from the roof terrace. I tried a collar with a bell and was very happy that it worked well. Bats are masters in recieving sounds, obviously any sounds.
But then she changed prey and brought careless sparrows. That's why I bought the birds be safe collar. She does not love it, but she accepts it. But I missed the fact with the "long hair style" - at the moment, there is only one article available for long haired cats. So the careless sparrows will need good eyes. As especially the forest cat breeds... Maine Coon, Norwegian and Siberian... are known as "hunting machines", birds would be safer with more collars for the fluffy kitties!