Cuckoos are parasitic, laying their eggs in other species’ nests. Each female cuckoo concentrates on one host species, which is usually the same as the one that raised her. Her eggs will closely resemble that species’ eggs and so will be accepted. She will lay one egg in each host nest, and up to a dozen eggs can be scattered throughout its territory, although they have been known to lay up to 25. Eggs will be laid in April-June. The incubation period is 12-13 days. Once they have hatched, the cuckoo chick will forcibly evict the host nestlings or roll the other eggs out of the nest. It will then take advantage of the host’s instinct to feed its young, even though it looks nothing alike. Cuckoos reach sexual maturity at the age of two years.