Of course completely agree with that, but I'm talking about it from a zoo guest experience here. After all, this is a zoo game first and foremost, so it should be about representing animals in a zoo setting. When you ask an average zoo guest which animals moved the most, they'll always refer to the bigger animals. When you ask them about frogs, they'll say that they hardly moved.
So that's why I like the exhibit box system at its core, small animals that you don't see moving a lot in zoos ( because let's face it, they're not the animals most people spend a long time watching) can easily be done by just doing a looped animation, because in real life you wouldn't really see them do more than that unless you spent more time with them.
Of course, it's a game, so it's generalization to a point, because games always have to compromise.