Homosexual Pairings in Birds

According to a study coming out, a researcher is suggesting that in some cases homosexual pairings in birds can be beneficial.  Live Science reports: After all, in evolutionary terms same-sex mating seems to reduce the birds' chances of reproductive success. But that's not necessarily so, according to a new study. In a given species, the sex with lighter parental duties tends to mate more, period — whether with the same or the opposite sex.

In 2007, a team led by Geoff MacFarlane, a biologist at the University of Newcastle in Australia, reported that male homosexual behavior was more common in polygynous bird species, where males mate with numerous females, and that female homosexual behavior was more common in monogamous species.

Intrigued, MacFarlane looked for help explaining the pattern in a theory predicting that whichever gender spends less time caring for young tends to have sex with more partners.

To find out whether the theory might extend to homosexual behavior, MacFarlane and his team exhaustively combed the literature for accounts of same-sex courtship, mounting, or pair bonding. They focused on the 93 bird species whose homosexual interactions scientists had seen in the wild. For each species, the team calculated the frequency of homosexual behavior as well as both sexes' contributions to parenting.

Overall, homosexual behavior amounted to less than 5 percent of all sexual activity in the 93 species, though in some cases it was much higher. And sure enough, there was a strong correlation between a species' mating system and its homosexual behavior. Whichever sex did less parenting also typically did more same-sex canoodling – basically because they could. This tended to be true for the promiscuous males in polygynous species. The balance shifted to females in socially monogamous species, where the sexes split the work more equitably.

You can read the full article here.