The aim of the project is to test hypotheses concerning resource allocation between phases of a single breeding bout in open nesting waterfowl. The project is designed to provide a complex description of energy investment into particular demands of current breeding in birds living under natural conditions as well as to test exact hypothesis by using manipulative experiments. Moreover, lab experiments under controlled artificial conditions are proposed to be done to reveal the relative contribution of incubation microclimate to the neonate phenotype at hatch. Specifically, our study will be focused on testing (1) the role of egg quality /size and composition/ and incubation environment on young quality at hatch, (2) variation in patterns of energy partitioning between individuals, (3) trade-off between female reproductive investment and self-maintenance. The study will provide an insight into relation between investment and output of the current reproduction in focal species.