Common cuckoo lay eggs that better imitate the host's eggs, the host species adapts and is more able to distinguish the cuckoo egg. A study of 248 common cuckoo and host eggs demonstrated that female cuckoos that parasitised common redstart nests laid eggs that matched better than those that targeted dunnocks. Spectroscopy was used to model how the host species saw the cuckoo eggs. Cuckoos that target dunnock nests lay white, brown-speckled eggs, in contrast to the dunnock's own blue eggs. The theory suggests that common redstarts have been parasitised by common cuckoos for longer, and so have evolved to be better
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