Classic first post in the suggestions topic. Bought this game less than a week ago and I can already feel it consuming my life.
Anyway, I know that lots of animals are going to be introduced in the future, but I'd specifically love to see many varieties of birds. Especially waterfowl. Specifically common loons. Imagine their haunting calls echoing over the lakes. Shivers. I guess gulls would be cool too. Maybe they could steal food out of your hands sometimes.
And horned owls and ravens in the forests. Golden eagles in the mountains. Maybe swallows as an effect similar to how butterflies are currently, but much higher above ground.
And if since there's a bit of a stone age kind of theme going on, maybe terror birds, or moa in some biomes instead of bears. That would be rad as heck.