Since when is flying the criteria determining being a bird? Are bats and moskitos birds? Are planes birds?
And flying is certainly not a requirement to be a bird: are baby birds not birds? Are injured or diminished birds not birds anymore? Are kiwis, dodos, ostrichs not birds?
As for penguins I can be flexible depending on how you cook it.
Since when is flying the criteria determining being a bird? Are bats and moskitos birds? Are planes birds? And flying is certainly not a requirement to be a bird: are baby birds not birds? Are injured or diminished birds not birds anymore? Are kiwis, dodos, ostrichs not birds?
As for penguins I can be flexible depending on how you cook it.