(From the Hill Pet Food company)
Your cat’s tail can tell you about what’s going on inside her head. Here’s what your cat is thinking, by tail:
Position: high. When your cat holds her tail high in the air as she moves about her territory, she’s expressing confidence and contentment. A tail that sticks straight up signals happiness and a willingness to be friendly. And watch the tip of an erect tail. A little twitch can mean a particularly happy moment. – Curved like a question mark. This tail position often signals a playful mood and a cat that’s ready to share some fun with you.
Position: low. Watch out. A tail positioned straight down can signal aggression. Although Persian cats tend to carry their tails low for no particular reason (* They are jerks.) – Tucked away. A tail curved beneath the body signals fear or submission. Something is making your cat nervous. – Puffed up. A tail resembling a pipe cleaner reflects a severely agitated and frightened cat trying to look bigger to ward off danger.
Moving: – Whipping tail. A tail that slaps back and forth rapidly indicates both fear and aggression. Consider it a warning to stay away. – Swishing tail. A tail that sways slowly from side to side usually means your cat is focused on an object. You might see this tail position right before your cat pounces on a bird. – Wrapped around another cat. A tail wrapped around another cat is like you putting your arm around another person. It conveys friendship.