Recent recearch proves that animals of all species (including insects and birds) can exhibit homosexual behavior, even when exposed to the opposite sex. It is most often exhibited when same-sex animals are placed alone with one another. However, in the studies, male animals have been observed mounting other males even when females in heat are available, according to studies conducted at the University of California (Riverside) and in Oahu, Hawaii. Females (this particular study followed sheep) have also been known to "sneak" and form sexual alliances with other females; the motivation appears to be raising their young together. Biology experts at the Columbus Zoo have observed this behavior as well; they say it is quite common in bonobos and manatees, as well as in insects and birds.
So the question is, what purpose does this homosexual behavior serve for the perpetuation of their species? None, since same sexes are unable to procreate. Apparently it is "natural," just as exhibited in humans. Either you "are" or you "are not." That comment may raise some eyebrows, but it is true. As a Psychology major in college, this author is aware of numerous identical twin studies (when they were raised by the same parents, or when they were separated at birth or shortly thereafter, and raised by different parents), when one of them ends up exhibiting homosexual behavior, and it basically boils down to "nature vs. nurture." This author believes that 'nature' takes precedence. Think about it; do you really "decide" if you want to be with a man, or a woman instead? You don't. You are just innately attracted to whichever sex you prefer. It is not a choice, either for homosexuals -- or -- for heterosexuals.
This study just proves what I've believed all along; that our 'instincts' guide us.