I'm a big fan of Doctorov , but in this case I would like a citation.

I'm making interested to see how the gender of the ewes was determined. I mean if the indicator of sexual attraction is indistinguishable from normal behavior: standing still how could one prove the sheep to be lesbian.

edit after reading through various research I've come to the conclusion that the researcher, Perkins, just admitted that there's no way to study lesbian behavior in ewes, as the have no visible sexual expression (that the researchers know about)

It's as much a statement of the importance of the researcher as they depend on clear intercourse-like behavior to explain attraction. They can't see that in ewes, as their sexual behavior is passive. 'if they don't hump we can't tell their sexual preference'

Which is a bit weird as they argue that in males sexual preference is hormonal, so that should register in females too. But that isn't studied as there's no interest.