The story of the cuckoo and the tiny reed warbler is an amazing one and perfectly illustrates how these birds have evolved to outsmart each other.
The cuckoo is a brood parasite. This means that it lays its eggs in the nests of other bird species; in this case the reed warbler. The reed warbler is known as the host.
The reed warbler is forced to rear the cuckoo chick, thinking that it is one of its own brood. This relationship has been going on for so long in Britain and parts of Europe that both birds have evolved ways of outwitting each other.
This worksheet looks at the way these two species have evolved in conjunction with each other.