TOD:
A shout-out to the Disney True-Life Adventures which are all splendid animal-based productions. The wizards at Disney back then were able to give these animals personalities that made the nature documentaries more personal and very involving.
One of the Bluths from Bluth Brothers Theatre--Don Bluth--worked for Disney as an animator. He drew birds. At a cast party, Don was asked to do his bird imitation. It was incredibily realistic. In order to draw birds well, of course, one must study them. Don had so many of the movements, so many of the nuances.
DR MATTH, I believe, was referring to documentaries rather than animation. But, as DR GEORGE would say, I just had to pass that on.