Little birds' personalities shine through their song -- and may help find a mate

Although birdsong can signal individual quality and personality, very few studies have explored the relationship between individual personality and song complexity, and none has investigated this in females, say Flinders University animal behaviour experts.

They have examined the relationships between song complexity and two personality traits (exploration and aggressiveness) in wild superb fairy-wrens (Malurus cyaneus) in Australia, a species in which both sexes learn to produce complex songs.

"Regardless of their sex or life stage, individuals that were more exploratory had more element types per song, which may be explained by the possibility that more exploratory birds approach and learn from a wider variety of tutors compared to less exploratory birds," says senior lecturer Dr Diane Colombelli-Négrel, from the College of Science and Engineering BirdLab at Flinders University.

"Additionally, more aggressive individuals produced songs with fewer syllables, and more aggressive fledglings, but not adults, had more element types per song. In birds, singing behaviours play a critical role in mating and territory defence."

The study illustrates that learned aspects of sexual signalling are personality dependent, and that this can have some potential fitness implications.

In a new study, published in Royal Society Open Science, the personality in males and females (including juveniles) was assessed by quantifying their exploration behaviour (novel environment test) and aggressiveness (mirror stimulation test) during short-term captivity.

First the birds were captured to measure their personality in short-term captivity. Researchers measured their exploration by placing them (in a novel environment test), and their aggressiveness (by using a mirror test).

After the birds were released, their songs were recorded over several months to assess individual variation in song complexity (i.e., element types per song, syllables per song) in relation to personality.

"Our study supports the idea that both male and female birds can advertise their personality when singing, which may be important for mate choice," Dr Colombelli-Négrel says.