[mlc9852]

But are they all birds?

[From many - one.]

Is that a joke question?

[JeffAtlanta]

But are they all birds?

Yes, they are all birds (class: aves). You said earlier that this was a serious question. Could you share what you're getting at?

I'm guessing that you're pointing out that they are the same 'kind'? If this is going to be your point, how many birds would Noah have taken on the ark?

[BMCDA]

But are they all birds?

Yes, they are all birds and I don't think anyone suggested otherwise. So I don't really understand the point of your question.

[Doctor Stochastic]

But are they all birds?

Yes, but not the same speices of birds. Do you consider all birds to be the same species? If so, that violates your interbreeding criterion. Please explain why you think that being birds matters in this discussion.