From Animals And Homophobia on Slate:
Homosexual behavior has been documented in hundreds of animal species, but the same does not hold for gay-bashing. For starters, few animals are exclusively gay. Two female Japanese macaques might have playful sex with each other on Tuesday, then mate with males on Wednesday. Pairs of male elephants sometimes form years-long companionships that include sexual activity, while their heterosexual couplings tend to be one-night stands. For these and many other species, sexual preferences seem to be fluid rather than binary: Gay sex doesn’t make them gay, and straight sex doesn’t make them straight. In these cases, the concept of homophobia simply doesn’t apply.
(Tipped by JMG reader Soundguy)