It is a bone of contention in the ranks of interstellar zoology whether the Ba (plural Bau) is actually a species at all, or merely a supernatural phenomenon which may or may not have a corporeal manifestation.
Worshipped by Ovine species universally, the Ba is quite simply described as a beautiful bird of prey with a human head, its hair fashioned very much in the style favoured by the Pharoahs of ancient Earth and the Ooblesires of ancient Cydonium, to name but a few.
Descriptions of the creature vary so little from galaxy to galaxy that I would almost be tempted to suggest that there is in fact only one Ba in this universe, and that he merely gets around a lot, in the spirit of a true gadabout deity.
Of the many sheep that I have spoken with - who, of all others, hold Ba in the highest regard, often calling his name well into the night, hoping for his swift return to favour them – it seems that he (nb: actual gender unknown) is strongly associated with power and impressiveness, symbolising the freedom of spirit to which all souls aspire and which sheep so rarely attain.
As no example of a Ba has ever, to my knowledge, been held in captivity I find this explanation quite convincing, and yet another bullet point in the case of sheep being so widely underestimated.
Although reports of feeding habits and tales of copulation do exist, they are little more than stories, so, at this point, I am reluctant to go into the details of these. If reports of the latter are true, however, I have yet to hear tell, or see evidence of, any naturally born offspring... Which brings us full circle to the first point in this assessment.
Right Thing to Say Should You Ever Meet One: I’m just not sure.