I'm planning to use 3D to create the raven animations to retain control - rigging this is going to be a challenge not to mention modelling but I have found some interesting videos to use as motion studies. I may end up hand drawing the raven animation depending on time and if the rigs look natural enough. The Psyop crow animations in an earlier post are brilliant but they obviously have some of the best 3D artists in the world working for them.

http://video.google.com /videoplay?docid=2594773814207562897#docid=-4253674915036639228

http://www.metacafe.com/watch/1811803/japanese_crow_take_flight_slow_motion/

http://stockfootage.wildlifehd.com/video_clips/DZ13_055