imply (color)_bird -> bird

BUR #11538 has been approved by @nonamethanks.

create implication white_bird -> bird
create implication black_bird -> bird
create implication blue_bird -> bird

They're all necessarily birds. Many white bird posts in particular aren't also currently tagged with bird.

I didn't even realize we had bird color tags. I'm not sure on the utility of these tags to be honest, but approving for now.

The bulk update request #11538 (forum #218099) has been approved by @nonamethanks.