So the animals went on board the Ark in pairs, one male and one female (well, to be more accurate, Genesis states some went on board as sevens... some pretty kinky sex there, I guess). That makes me wonder about those species of animals with no males, such as the New Mexico whiptail lizard (must have been a long walk to get to the Ark, but that's another story). All of the whiptails are females, and they reproduce parthenogenetically (virgin birth, you know). Not only that, but the females engage in mounting behavior with each other. So did Noah acknowledge these animal lesbians as they came on board? Or did he just pretend that one was a male?
Incidentally, if you are not aware, homosexuality is far from "unnatural". To find lots and lots of examples in the animal kingdom, take a look at Biological Exuberance, by Bruce Bagemihl.