Some cuckoos lay blue eggs as a form of brood parasitism, where they lay their eggs in the nests of other birds and let them raise the young. The blue eggs mimic the eggs of the host bird, helping to ensure that the cuckoo's eggs are accepted and incubated by the host. Cuckoos that lay blue eggs include the common cuckoo (Cuculus canorus), found in Europe and Asia, and the great spotted cuckoo (Clamator glandarius), found in Africa and southern Europe.