As for the zoological perspective: it's not the facts that matter, but the way they get used to service the human patriarchy.
Both willing sex and rape are common among many species. What's certain, however, is that females do not willingly choose the dominant males. Even when they seem to do so - it's a survival strategy to ward off more violence from other males towards them and their babies. In many species they sneak off to mate with the less violent males while the dominant male isn't looking with great risk to themselves. Again, like Vestal said - the females may very well like sex when they're given choice in the matter. Just like the human ones.
What's depressing is that our genetic cousins the chimps are REALLY high on the rape scale. Practically all of their mating is various strategies of sexual coercion, much of it violent. Generally, more violence = more reproductive success for a male. But that is through rape and intimidation, not because the female gets off on it like the MRAs claim. Females get off on somewhat consensual, female-friendly sex like the bonobos do it.
Vestal is correct to cite dolphins because they're crazily intelligent...and still highly rapey despite that.
My point about non-patriarchal (or at least not as brutally so) societies is that they either didn't seek to dominate the planet so def not power hungry, or that the oppression they practiced was ineffective in that goal. Which is why they're all gone past the colonial stage.
Phew, I've written a thesis here...