Are unusually colored eggs a signal to potential conspecific brood parasites?
It has previously been suggested that some species of birds make the last egg in their clutch pale as a signal to potential conspecific brood parasites that incubation has commenced. Here, we use game theory to show that the signaling function of pale eggs can be evolutionarily stable and resistant to cheating and to demonstrate that such a signal can only be maintained under strict conditions. The key conditions are, first, that there is a cost associated with the production of pale eggs (in particular, the cost of a pale egg produced early in the clutch must be more expensive than the cost of one produced later in the clutch) and, second, that the cost of making the last egg pale is not too great (relative to the costs of parasitism). We discuss the likelihood of these conditions being met in real systems and suggest empirical tests that would differentiate this theory from alternative nonadaptive explanations for pale eggs.
Ruxton
G D
GD
Division of Environmental and Evolutionary, Biology Institute of Biomedical and Life Sciences, University of Glasgow, Glasgow, United Kingdom.
Broom
M
M
Colegrave
N
N