Sketches from the Natural History Museum in Göteborg.
What can I say, stuffed animals make great models, as opposed to living birds:
Those are sketches from life -- damn those critters are fast. ;)
While sketching I tried to remember how Disney's birds looked like, but I was out so I couldn't really check them out. I relied on a vague memory and, well, a feeling of them -- which, I suppose, it's all what gesture drawing should be all about anyway.
By the way, kudos to Disney and his animators for creating birds everyone remembers, even if they never paid any attention to them. ;)