Egg recognition in Japanese quail

Egg recognition allows birds to reduce the costs of heterospecific or conspecific nest parasitism, by allowing them to reject foreign eggs or abandon parasitised clutches. However, the precise phenotypic characteristics of eggs that are recognised and compared are not well understood. Using Japanese quail (Coturnix japonica), which exhibit extremely high between-female and low within-female variation in egg colour, maculation patterns and shape, I show that females can learn to recognise the salient characteristics of eggs from a given clutch (not necessarily their own) and can use this learned template to discriminate against foreign eggs with a high probability when the eggs are phenotypically distinct. Specifically, female quail appear to use both maculation pattern and, to a lesser extent, egg shape to make these decisions. These findings are discussed with respect to cognitive mechanisms of egg recognition.