This video attempts to explain why the Pootis Birds have not return to this era.
If you don't know what a Pootis Bird is, it was made by a YouTuber who goes by Dr. Face and has the ability to fly like birds and deploy miniguns from their butts. Yes, I am serious.
What they lack is intelligence, and that means you can trick them easily. I heard that they like a certain sandwich made out of whole grain bread mixed with dolphin's milk, and that when dropped, they will stop whatever they're doing and chase after the scent of dolphin's milk.

Whatever's the case, the hunters has successfully hunt them down, despite the minigun-deploying butts, and now they are in hiding, to the point of being declared extinct.