Among other species we have a few different cardinals come by, which we recognize individually at this point. One of the male cardinals is chill and doesn't care whether there are other birds at the feeder, but another one is a dickhead and will physically hurl himself at every bird within a one meter radius. The other birds know this! If the chill cardinal comes over the other birds will not care. But if the aggro one comes they will scatter before he even threatens them! Just funny to see how birds recognize other individual birds from other species.