| Abstract: | In this study we examine maternal yolk hormones in the budgerigar (Melopsittacus undulatus), which give the female the ability to modify offspring phenotype to their future environment. We study the variation of maternal yolk hormones within and between clutches. We search evidence for possible mechanism of variable hormone deposition in the yolk and we study the effects of variable deposition for the offspring, in the short term as well as in the long term.- |