Growing up, my parents had indoor/outdoor cats. They belled them. The cats still caught birds. When I bought my first house, the people who lived there moved out of state and left their cat. He was a great hunter, so I belled him. He still caught everything - birds, rabbits, mice, gophers...you name it. He had learned to stalk so carefully so the bell wouldn't ring. He was also a Houdini cat, and I found his collar all over our land. I don't know how he got it off, but he always did. The only 100% way to guarantee your cat won't kisll things is to keep them in - and even then any insects that get in the house are fair game!