Although homosexual behavior is very common in the animal world, it seems to be very uncommon that individual animals have a long-lasting predisposition to engage in such behavior to the exclusion of heterosexual activities. Thus, a homosexual orientation, if one can speak of such thing in animals, seems to be a rarity.

Queer Science: The Use and Abuse of Research Into Homosexuality (ed. MIT Press, 1996) - ISBN: 9780262121996