Cat tail signs: What your cat's tail tells you she always vibrates her tail at this exact spot very.. confused?? anyone else experienced this? Why Does My Cats Tail Vibrate A Guide to What Your Cat is Communicating: A cat's tail is far more than just a balance toolit is a sophisticated emotional barometer that broadcasts their internal world. When your feline It looks like they are vibrating. When a cat's tail shoots straight up and quivers or rattles at the tip, it is the highest form of excitement they can show. It's a How to Read Your Cat's Tail Language