system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why there are no sky-colored birds?

Why they don't mimetize with the sky?
gpt
For the most part, birds are safe in the air (the exception being from some birds of prey which usually strike from above, not below). Birds are vulnerable when on the ground, so it makes more sense to blend in with their usually terrestrial habitat than the sky. Or they are brightly colored to attract a mate, simply building spending most of their time in remote, hard-to-reach areas where few predators can reach them.