Alley's tail jerks....

My Alley is two years old now and just recently started jerking her tail. Seems it's some type of communication because she does it differently, like how cats can sound different when they meow. Does anyone know what she might be trying to communicate? I can't pinpoint her mood when she does it, but I notice it when I talk to her, like it is a response to my voice?

Is this a vertical tail that's jerked or twitched? I think it indiciates positive mental stimulation: curiousity, eagerness, anticipation, pleasure, happiness. "I'm happy to see you!!"

Here's a great guide to cat communication, both vocal and "body language"

http://www.messybeast.com/cat_talk2.htm

Zoey does this funny little thing that I call her jitter bug tail when she's happy to see me or runs over to me. kinda like a rattle snake only it's most of her tail.

Tino and Kiko do it here ........ I looked it up when they first did it and I read it was a "Im happy to see you" thing. They are rubbing back and forth with their heads on my legs when they do it too