Other song features, such as diversity, were not correlated with clutch size. The study also showed that male blue tits with higher vocal consistency had higher reproductive success as measured by the number of eggs in their nest - further adding to the evidence that vocal consistency is a skill found in good quality individuals - those who will contribute genes to future populations. "We found that when males sing different song types, or introduce silent pauses between songs, it reduces female habituation and help retain her interest." Repetition is needed by the male to perfect his singing skills, however this repetition may carry a cost where the female loses interest over time. A song may also be repeated during a singing bout. "Many bird species produce trilled songs where the same note is repeated in quick succession. Precisely hitting those repetitive notes is the way a male bird can demonstrate to potential mates these qualities, which also cut across social status, reproductive output, longevity, sexual attractiveness and ability to defend territories.
Lead author Dr Javier Sierro, whose PhD thesis at Lancaster University included this work, said, "In songbirds, singing requires the execution of complex motor patterns within the bird. The researchers believe that a male bird's ability to consistently hit the same note in a song is a signal to females, and competitors, that they have strong motor skills, which carry over to other essential qualities in a good mate. The results may explain why birdsong in most species is not hypervariable and constantly changing but shows some moderate variation - balancing the reliable signal of quality against the need to avoid the female habituating and losing interest. Their response gradually declined (habituated) until it was reignited when males switched to a different song type. They devised an experiment which involved playing song recordings to receptive females and discovered that male vocal consistency - repeating the same pattern of notes with high precision - was the key song feature that made females sexually excited.īut while singing exact copies of the same note was sexy, it also became 'boring' for females. Over two years, the researchers recorded and analysed 7,000 songs of wild blue tits breeding in closely monitored nest boxes near Lancaster University. The findings from the study, by scientists from Lancaster University and Manchester Metropolitan University, sheds new light on the evolution of bird song. However, the males need to ensure they have a selection of different songs in their repertoire if they are to hold a female's attention and prevent her from getting bored.
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