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Updated: Jun 14, 2026
07:34
Probing the Limits of Egg Recognition Using Egg Rejection Experiments Along Phenotypic Gradients
Published on: August 22, 2018
Does egg colouration reflect male condition in birds?
Jesús Martínez-Padilla1, Heather Dixon, Pablo Vergara
1Aberdeen Centre for Environmental Sustainability (ACES), University of Aberdeen & The Macaulay Institute, School of Biological Sciences, Tillydrone Avenue, Aberdeen, UK. j.mart@abdn.ac.uk
Die Naturwissenschaften
|March 24, 2010
Summary
Bird egg colouration, specifically protoporphyrin pigmentation in Eurasian kestrels, is linked to male condition, not female quality. This suggests egg colour may indicate quality, but not as a post-mating sexual signal.
Area of Science:
- Avian reproductive biology
- Animal behaviour and ecology
- Evolutionary biology
Background:
- Egg colouration in birds is an understudied area with potential adaptive significance.
- A recent hypothesis proposes egg pigments (biliverdin, porphyrin) signal female quality to males post-mating.
- Courtship feeding by males influences female condition before egg-laying in many bird species.
Purpose of the Study:
- To investigate the influence of male feeding and female characteristics on egg protoporphyrin pigmentation in Eurasian kestrels.
- To explore the potential costs and quality indicators associated with producing pigmented eggs.
- To test the hypothesis of egg colouration as a post-mating sexual signal.
Main Methods:
- Descriptive assessment of egg pigmentation in relation to female phenotype, condition, breeding parameters, and male body condition.
- A food-supplementation experiment to investigate the cost of egg pigmentation.
- Analysis of hatching success and egg mass in relation to egg colouration under different feeding regimes.
Main Results:
- Older females and those with greyer tails produced more pigmented eggs.
- Male body condition was the sole predictor of egg colouration when combined with female variables.
- Egg colouration was not directly enhanced by food supplementation, but hatching success and egg mass correlated with colouration in supplemented pairs.
- Results did not support egg colouration as a post-mating signal in this species.
Conclusions:
- Egg colouration in Eurasian kestrels appears linked to male condition, suggesting it may signal egg quality.
- The cost of producing pigmented eggs is not explained by female quality but by male condition.
- The findings challenge the theory of egg colour as a post-mating sexual signal in species where males influence female condition.
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