Because your cat is enticed by the bird. My cat often sits by the window to watch birds and squirrels. Tail twitching is a normal activity.
If you only see cats with their tails standing up, that is a good sign because it generally indicates a confident and well adjusted animal. A fearful or aggressive cat will hold its tail down, and may lash it from side to side.
It's possible but mostly they just move it...
Cats don't really "wag their tails". If your cat is lashing its tail from side to side, it's probably upset about something. A cat may twitch the tip of its tail, which is somewhat different; it doesn't seem to really mean anything other than "I can twitch the tip of my tail, so I think I'll do that." That's not entirely true; cats usually twitch the tip of their tails when they are hunting.
Your cat's tail may quiver when she sees you because she is trembling with excitement. When a cat sees a bird or mouse their tail sometimes will quiver in excitement. A quivering tail in response to petting is a nervous system reaction to the unusual stimulation. In addition to all of those things an intact male cat quivers his tail while holding it high as he stands in preparation to spray a urine mark in his territory.
the bird that has a tail like a fan is called a 'Peacock'
Bird
a bird is a bird
no
if your'e saying it flicks and swings wildly side to side, you cat is angry or it wants something. if its outside and their tail flicks, it sees something it wants to hunt cats have different emotions :D
yes they do it is their equivalent of a cats hair standing up when they are nervous
Peacock
angry bird because he/she is angry