Dunnock two or three adjacent female territories overlap one male territory, and so polygyny is favored, with the male monopolising several females. Polygynandry also exists, in which two males jointly defend a territory containing several females. Polyandry, though, is the most common mating system of dunnocks found in nature. Depending on the population, males generally have the best reproductive success in polygynous populations, while females have the advantage during polyandry. Studies have illustrated the fluidity of dunnock mating systems. When given food in abundance, female territory size is reduced drastically. Consequently, males can more easily monopolise the females. Thus, the mating
Common shelduck rabbit burrows, tree holes, haystacks or similar. In winter it is common on suitable estuaries and tidal mudflats as well. This bird is one of the species to which the "Agreement on the Conservation of African-Eurasian Migratory Waterbirds" (AEWA) applies. The young will dive under water to avoid predators and the adults will fly away from them to act as a decoy. Common shelduck The common shelduck ("Tadorna tadorna") is a waterfowl species of the shelduck genus, "Tadorna". It is widespread and common in Eurasia, mainly breeding in temperate and wintering in subtropical regions; in winter, it can also be