Expression of genetic variation in body size of the collared flycatcher under different environmental conditions

Heritability of body size in two experimentally created environments, representing good and poor feeding conditions, respectively, was estimated utilizing cross-fostered collared flycatcher Ficedula albicolis nestlings. Young raised under poor feeding conditions attained smaller body size than their full-sibs raised under good feeding conditions. Parent-offspring regressions indicated lower heritability of body size under poor than under good feeding conditions.