Low down on the singing

Abstract

The male European starling is well known for its diverse range of song phrases, some of which have sometimes been recognizably poached from those of other species and even from anthropogenic sources: it is not entirely unusual to hear the odd telephone ringtone or car alarm amongst their complex songs. There’s evidence that the wide range of the bird’s song phrases provide an indication of a male’s overall quality and is the subject of sexual selection amongst females. It is thought this is because the development of the neural pathways of song production and learning develop early in life and may be sensitive to developmental stresses. Experiments have shown that nutritional stress during development can lead to a reduced song range in adult males. But could other factors also contribute to the adult males’ final repertoire? Out of the breeding season, starlings mostly forage in groups in which a social hierarchy develops involving aggressive encounters between individuals. From other studies it is known that such encounters can lead to raised levels of stress hormones. But the relationship between stress hormones and developmental stress is not clear, so a team of researchers have examined a group of captive starlings for evidence of a link between, nutrition, social and hormonal status and song repertoire. K.A. Spencer, K.L. Buchanan, A.R. Goldsmith and C.K. Catchpole of the Universities of Cardiff, Bristol and Royal Holloway, University of London, report in the Proceedings B of the Royal Society of London (published online) work with a group of captive birds. Fortyeight juvenile starlings were held in four groups of twelve animals. Two groups were held under an unpredictable food supply, with the other two provided with unlimited food. In each group the dominance hierarchy was determined and the effect of nutritional stress and social rank on song complexity investigated. When they examined the results, they found that birds under nutritional stress produced smaller song repertoires than those with unlimited access to food. However, they also found that males of more dominant rank produced larger repertoires than those of lower rank in all the cages. Social status was not related to individual weight, testosterone levels or stress hormone levels. And birds under nutritional stress maintained a body mass no lower than controls. The results suggest that birds of lower social rank may incur a cost potentially due to limited access to food or reduced ability to practice their song. The authors warn that because the birds were captive, aggressive encounters may have been heightened but their results suggest that female’s keenness on the range of her potential mate’s song may not only give an honest indication of his nutritional history but that of his past social status too. ‘This study is, to our knowledge, the first to show the effects of developmental stress on repertoire size in a bird with a sexually selected song structure. It has also uncovered a possible link between social status during development and song quality,’ the authors say. Males, therefore, may be singing for more than just their supper with their complex songs. Low down on the singing

DOI: 10.1016/j.cub.2003.11.036

Extracted Key Phrases

Cite this paper

@article{Williams2003LowDO, title={Low down on the singing}, author={Nigel Williams}, journal={Current Biology}, year={2003}, volume={13} }