Feel free to show me the MMOs that have lots and lots of avian creatures that instead of being plainly visible just chill in trees and dive-bomb you.

Unlike normal games most monsters generally do the same thing, they wander around and attack or ignore you. Custom maping zones for a species of birds/bats would be a massive waste of time considering what else they could be doing instead. Then again if a "Floating bird" breaks your mind so badly that you ar eno longer immersed in the video game.

Perhaps you need to go hunt real avian creatures who are more than willing to sit in trees and then swoop down onto your face. Hell we should add the mechanic that birds would just...fly away when they noticed you are going to beat the shit out of them.