"Wingless Migration" Animation

Hey, Blenderers! I started making this for an Animation Challenge a few weeks ago, but I finally got some time to expand it more towards what I wanted it to be.

http://workingweek.org/anim/wingless_thumb.jpg
http://workingweek.org/anim/wingless_migration.avi
2.4 MB, xvid (basically divx/mpeg-4) avi

Let me know what you think! I might try to add sound to it, but I want to feel fairly confident with the visuals before I do that (which is kind of backwards, but the sound should be pretty simple and easy to sync to existing visuals).

Cheers!
-Mike