Before they start mating as adults, birds like the zebra finch spend their adolescence socializing with members of the opposite sex. And it turns out that their childhood friendships end up predicting how well they will do at the mating game later in life.
That’s the finding of new research by Mylene Mariette and her team at France’s University de Saint-Etienne. This appears to be the courtship equivalent of a well-documented phenomenon known as the loser effect, which says that male birds and other animals that lose fights with fellow males undergo a drop in hormonal levels that makes it less likely to win future fights. Dr. Mariette and her team artificially controlled just who young zebra finches would pair off with during their adolescence. Those males that successfully paired with a female had much greater success in adult courtship than those that didn’t, while a male’s ability to socialize with other males appeared to have no bearing on future mating success or failure. Talking to the BBC, Dr. Mariette explains just what this finding means:
“We know that social interaction is important for some aspects of development, like the role of males to teach youngsters to sing, but so far no study has looked at the effect of how interaction between juveniles affects their behavior as adults. Like winning a fight, successful mating is a positive social interaction. We know that animals are able to pick up chemical cues from others, so they could potentially detect a change in hormone levels. In the mating context we have good reason to expect the same mechanism to happen. Just like an animal wanting to know how good a male is at fighting compared to others, they may also want to know how attractive he is.”
Dr. Mariette says there are two leading potential explanations for this effect. It’s possible that those who fail to socialize as adolescents take a dim view of their own abilities, and so they don’t even attempt to mate with the most desirable females as adults. The flip side of that is also possible, as females actively reject those males who weren’t good at socializing when they were young.