The importance of genetic evidence for identifying intra-specific brood parasitism

Abstract

Intra-specific brood parasitism is widespread among birds. When genetic evidence is not available, criteria like super-normal clutch size, high within-clutch variance in egg morphology, and shorter than normal laying intervals have been used to identify parasitized broods. Here we report genetically determined parentage of a clutch of super-normal size in a species with fixed clutch size, the northern lapwing Vanellus vanellus. Results from multi-locus DNA fingerprinting revealed no loss of parentage in this brood. Furthermore, no loss of parentage was found in another clutch with a high variance in egg size and colouration. These findings add to previous evidence that reliable classification of brood parasitism requires molecular analysis.