Dunnock relatively lower success for females. In times of scarcity, female territories expand to accommodate the lack of resources, causing males to have a more difficult time monopolizing females. Hence, females gain a reproductive advantage over males in this case. The dunnock possesses variable mating systems. Females are often polyandrous, breeding with two or more males at once, which is quite rare among birds. This multiple mating system leads to the development of sperm competition amongst the male suitors. DNA fingerprinting has shown that chicks within a brood often have different fathers, depending on the success of the males at monopolising
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