What is she trying to tell me? Vibrating tail??? : r CATHELP Why does my cat shake her tail like this? Cat Tail Language: Common Positions & What They Mean You asked and we picked one question to answer this week: "Why does my cat shake her tail like a rattlesnake?", We've got the answer below from behavior professional Kenzie Korpela, IAABC SBA, CFVA. What is your cat's tail telling you? Blue Cross