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Carotenoid-based nestling colouration and parental favouritism in the great tit

Tschirren, Barbara ; Fitze, Patrick ; Richner, Heinz

In: Oecologia, 2005, vol. 143, no. 3, p. 477-482

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    Title
    • Carotenoid-based nestling colouration and parental favouritism in the great tit
    Author
    • Tschirren, Barbara. Division of Evolutionary Ecology, Zoological Institute, University of Bern, 3012, Bern, Switzerland
    • Fitze, Patrick. Behavioural Ecology Group, Zoology Department, University of Cambridge, CB2 3EJ, Cambridge, UK
    • Richner, Heinz. Division of Evolutionary Ecology, Zoological Institute, University of Bern, 3012, Bern, Switzerland
    Document Type
    • Postprint
    OAI-PMH Identifier
    • oai:doc.rero.ch:315540
    Summary
    While elaborate carotenoid-based traits in adult birds may have evolved as honest signals of individual quality in the context of sexual selection or other social interactions, the function of carotenoid-based colours in juveniles is less well understood. We investigated the hypothesis that carotenoid-based nestling colouration has evolved in response to parental preference of intensely coloured offspring during food provisioning. In a field experiment, we manipulated nestling plumage colouration by a carotenoid-supplementation and analysed the parental food provisioning behaviour before feather appearance and at the end of the nestling stage. Carotenoids per se did not influence the nestling's begging behaviour or parental feeding decisions and we found no evidence that carotenoid-based colouration in nestling great tits has a signalling function in parent-offspring interactions. Parents did not discriminate between intensely coloured and control offspring in their food provisioning and in accordance with this finding intensely coloured nestlings were not heavier or larger at the end of the nestling stage. Alternative explanations for the evolution of carotenoid-based colours in nestling birds are discussed