Ardea
Official journal of the Netherlands Ornithologists' Union

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Mace R. (1987) Why do birds sing at dawn? ARDEA 75 (1): 123-132
The function of singing at dawn is likely to be different for birds singing to attract mates and those that are already monogamously paired. Unpaired males will spend the maximum possible time singing, constrained only by darkness and the need to forage, so such factors as foraging profitability, overnight variation in energy requirements, the arrival time of migrant females, and the acoustic properties of the environment will influence when they sing. All these factors can favour a dawn chorus. Monogamously paired males may sing to keep other males out of their territories and mate guard, and possibly to attract extra-pair copulations themselves. In these cases singing will be influenced by when females are fertile, and there is evidence that birds have a short 'fertile window' just after egg-laying, which for most passerines is at dawn. Various species have been shown to be able to adjust their singing behaviour to each of these factors. The factors which have the strongest influence on dawn singing in the Great Tit are female emergence time at dawn and her stage in the nesting cycle, two factors that suggest the dawn chorus is associated with female fertility in this monogamous species.


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