Why does my lovebird puff up,shake her tail feathers and chirp?

Birds usually "puff up" when they are settled and content (and also to retain internal heat), same with the shaking of the tail feathers and the chirping. She may do it when settling in for a nap or to sleep, after eating a bit, or relaxing. On the flip side though, if your lovebird is puffed up ALL the time, it could mean illness. Be vigilant, if she seems puffed up all the time- call your avian vet for advice. :)