Science & Environment

Early female bonds boost male birds' mating success

Zebra finch on branch
Image caption Forming male-female pairs when young has been found vital for mating success

Male zebra finches that fail to socialise with females during adolescence are less successful at courtship later in life, a study says.

This effect mimics the "loser effect" where, after a defeat, an animal is more likely to lose a subsequent fight.

Social friendships at a young age were also found to be more important than physical and social attractiveness.

The findings are reported in Proceedings of the Royal Society B: Biological Sciences.

The loser effect has been well demonstrated in many species, from spiders and fish to birds. After a fight hormonal levels change which negatively affects performance in further fights.

Now scientists have found a similar effect for mating. Adolescent males who failed to pair with a juvenile female were later unsuccessful with females they encountered in adulthood.

Scientists also paired young males as a control in the experiment. They found that if males failed to pair with another male, it had no effect on their later success.

Judging fights

Mylene Mariette, from the University de Saint-Etienne, France, and lead author of the study said: "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 behaviour as adults."

She explained that there are two ways in which the loser effect could be operating.

In the first, losers may judge past experience of their own abilities - of fighting or attractiveness - and adjust their behaviour accordingly "to avoid losing time and energy".

In the second, knowledge of a past loss or rejection may change the way an opponent or potential mate reacts to a loser, for example, females may be less willing to mate a previously rejected male.

"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," Dr Mariette added.

"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."

Not a loser forever

Fortunately for the males, the loser effect does not last forever, sometimes only for a few hours. "He may just court less attractive females. He's not a loser for life," Dr Mariette told BBC News.

Two months after rejection by their female companion, the males were no longer less successful with new females, but "better quality males were still preferred".

The loser effect in mating could be widespread amongst other animals but for now "it's too early to tell", she said.

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