‘Cheating’ birds change their tune — and females can tell

Female pied flycatchers can discern a male's commitment level by his song, according to a recent study. When a male mates and relocates to a new territory, his singing style changes subtly - his songs become shorter and he repeats syllables less frequently. Scientists played these altered songs to female pied flycatchers, and the females responded differently to those sung by males who were already paired versus those by unmarried males.

This indicates that the females can tell the male's relationship status from his song alone. The researchers suggest this could be an evolutionary adaptation. By changing their song patterns, males may be better able to court additional females without their first mate detecting their infidelity. The study, however, does not suggest that the males are intentionally deceiving their partners.