Birds of feather flock together?

It means people and animals tend to stick to their own kind.

Birds of a feather flock together means that people who have many similarities intend to hang out together.

Because they are limited by the collective intelligence of only their flock.

"Birds of a feather", etc.. is a simple way of saying that like draws like. There is comfort in recognition, so we tend to choose our companions by how much alike we are. The opposite, "opposites...

The saying is "Birds of a feather, flock together." I don't know who wrote it but it implies that people that have the same interests or likes, or feelings will gather together just as birds do....