Budgies in their natural habitat. Photo by David Cook Wildlife Photography (kookr).I've just set myself up a Google Scholar alert for papers on the evolution of same-sex mating behavior. The plan is, I'll post some brief notes on anything interesting that shows up in my inbox. First up: bisexual budgies!
Male budgerigars—or parakeets, to those of us in the States—live in female-dominated social groups when they're not caged in a petstore. In these groups, apparently, it's quite common for pairs of males to engage in behaviors that look a lot like what males do when courting female budiges. It's been hypothesized that this same-sex courting is practice for the real, reproductive deal. If that were the case you'd expect that male budgies who put in more time practicing with other males would have better luck with females later on.
However, when Puya Abbassi and Nancy Tyler Burley of the University of California Irivine compared the frequency with which individual male budgies engage in same-sex courting to their later success with females, they found a negative relationship—males that had more same-sex interactions were less likely to find female mates [$a]. The authors propose that the same-sex interactions are actually males assessing each others' social status. That would square with Abbassi and Burley's observations if low-status males, who are less likely to get lucky in the mating game, spend a lot more time sorting out relative rankings amongst themselves—and this is what the authors suggest may be going on.◼
Abbassi, P., & Burley, N. (2012). Nice guys finish last: same-sex sexual behavior and pairing success in male budgerigars Behavioral Ecology DOI: 10.1093/beheco/ars030