That does not explain though, why there should be more animals than ever in a pack. In the end, flying is only a little more than deep diving in the air. All we need is some places to land for birds. And if we are lucky and aviarys are modular, then the mesh pieces do already a great job I believe. Plus, like with the aquatic, a new barrier could be added. But new assets would mean less animals and not more. As I said, I'm fine with an animal pack, I actually would prefer having one. But even more animals? Seems unbalanced, unless we get more animals in each pack forever thereafter.
I would have been on board with "more than 8 animals" when we'd got at least 8 with the aquatic pack, because well, new mechanic. And for the release of the aquatic pack only one base game animal got updated - wouldn't that be equivalent to updating the Flamingo? (Though, to be fair, I don't want them flying unless we can turn in off for them.)