Dec. 18, 2012 — Male birds use their song to dupe females they have just met by pretending they are in excellent physical condition.
Just as some men try to cast themselves in a better light when they approach would-be dates, so male birds in poor condition seek to portray that they are fitter than they really are. But males do not even try to deceive their long-term partners, who are able to establish the true condition of the male by their song.
Researchers at the University of Exeter studied zebra finches to establish how trustworthy birdsong was in providing honest signals about the male's value as a mate. Singing is a test of the condition of birds because it uses a lot of energy. Fit and healthy birds are thought to be able to sustain a high song rate for longer, making them more attractive to females.
The research team, which included scientists from the Université de Bourgogne in France, looked at short and longer encounters with unknown females, as well as patterns of song around females who were familiar to them.
The team discovered that males in poor condition could "cheat" and vary their song to give a false impression to stranger females. But they did not even try to fool those who knew them, who used song as a reliable test of their underlying qualities. The research is published on December 19 in the journal Proceedings of the Royal Society B