Advise Needed: Random movie play

Please have a look at this:

http://www.gauravsobti.com/

The birds are just simple buttons for now.

I have created an animation which has the bird fly up & chirp, and would like to replace all the birds with this.

For now I have replaced all buttons w/ the animation on stage and they all lie on the 1st frame. But thats kinda not what I want.

How can I get any one bird animation to play, one at a time, at a random interval of 15-45 seconds?

Wud gr8ly appreciate ur prompt suggestion.

Best,
wirefree