Experimental support for the makeup hypothesis in nestling tawny owls (Strix aluco)

Romain Piault, Julien Gasparini, Pierre Bize, Mariane Paulet, Kevin McGraw, Alexandre Roulin

Research output: Contribution to journalArticlepeer-review

39 Scopus citations

Abstract

Body condition can affect coloration of traits used in sexual selection and parent-offspring communication by inducing rapid internal changes in pigment concentration or aggregation, thickness of collagen arrays, or blood flux. The recent "makeup hypothesis" proposes an alternative honesty-reinforcing mechanism, with behaviorally mediated deposition of substances on body surfaces ("cosmetics") generating covariation between body condition and coloration. In birds, the uropygial gland wax is actively spread on feathers using the bill and changes in its deposition rate may cause rapid changes in bill and plumage coloration. Using tawny owl nestlings, we tested 3 predictions of the makeup hypothesis, namely that 1) quantity of preen wax deposited accounts for variation in bill coloration, 2) an immune stimulation (induced by injection of a lipopolysaccharide [LPS]) impairs uropygial gland wax production, and 3) different intensities of immune stimulations (strong vs. weak stimulations induced by injections of either LPS or phytohemagglutinin [PHA], respectively) and high versus low food availabilities result in different bill colorations. We found that 1) preen wax reduced bill brightness, 2) a challenge with LPS impaired uropygial gland development, and 3) nestlings challenged with LPS had a brighter bill than PHA-injected nestlings, whereas diet manipulation had no significant effect. Altogether, these results suggest that a strong immune challenge may decrease preen wax deposition rate on the bill of nestling birds, at least by impairing gland wax production, which causes a change in bill coloration. Our study therefore highlights that cosmetic colors might signal short-term variation in immunological status.

Original languageEnglish (US)
Pages (from-to)703-709
Number of pages7
JournalBehavioral Ecology
Volume19
Issue number4
DOIs
StatePublished - 2008

Keywords

  • Bill coloration
  • Immune status
  • Makeup hypothesis
  • Preen wax
  • Preening behavior
  • Uropygial gland

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Animal Science and Zoology

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