Original Paper

Naturwissenschaften

, Volume 97, Issue 5, pp 469-477

First online:

Does egg colouration reflect male condition in birds?

  • Jesús Martínez-PadillaAffiliated withAberdeen Centre for Environmental Sustainability (ACES), University of Aberdeen & The Macaulay Institute, School of Biological Sciences Email author 
  • , Heather DixonAffiliated withSchool of Biological Sciences, University of Aberdeen
  • , Pablo VergaraAffiliated withSchool of Biological Sciences, University of AberdeenDepartamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC)
  • , Lorenzo Pérez-RodríguezAffiliated withDepartamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC)
  • , Juan A. FargalloAffiliated withDepartamento de Ecología Evolutiva, Museo Nacional de Ciencias Naturales (CSIC)

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Abstract

How colouration provides information about individuals in birds has been a central issue in recent decades. Although much information has been derived, little is known about the adaptive significance of egg colouration in birds. A recent idea suggests that biliverdin- and porphyrin-pigmented eggs may act as a post-mating sexual signal for males to assess female quality. In birds, it is common for males to influence prelaying female condition by courtship feeding. Using Eurasian kestrels, a species that lays protoporphyrin-pigmented eggs, we descriptively assessed the influence of male feeding on egg pigmentation by considering female phenotype, condition, breeding parameters and male body condition. We found that older females and females with greyer tails (an index of individual quality) produce highly pigmented eggs. However, male body condition was the only variable that explained egg colouration when considered together with the female-related variables. Therefore, females that mated with males in better condition laid highly pigmented eggs. With the same species, we also explored the cost of producing protoporphyrin-pigmented eggs using a food-supply experiment before the laying period. Food supplementation did not increase egg pigmentation, but hatching success and egg mass were positively related to egg colouration only in food supplied pairs. We suggest that egg colouration might be costly to produce and probably suggests egg quality. However, this cost cannot be explained by female quality, but by male condition instead. In general, our results do not support the theory that egg colouration is a post-mating sexual signal in species where males determine female condition at the time of laying.

Keywords

Eurasian kestrel Food supplementation Egg colouration Male condition Female phenotype