According to the story, ravens and doves were both on the ark - maybe even more birds. Although all birds, they were still considered different "kinds".
Not sure if this is where you are going with this, so disregard if it's not.
Just making sure I understood correctly regarding species, though I'm still not sure I do. Anyway, I find it strange that different breed dogs (and other animals) can reproduce with each other but it seems like birds can't/don't. For example, can a blue jay and cardinal reproduce? Or do they just choose not to? I'd never really given it any thought until this thread. And I really don't mean to take up your time - but I am curious. Thanks.