Brood parasitism

Abstract Brood parasitism is the most fascinating feature of cuckoo biology. Cuckoo parasites use other species to rear their young, and how the behavior evolved as a reproductive strategy demands an explanation (Darwin 1859, Hamilton 1972). Brood-parasitic cuckoos lay their eggs in the nests of other species, their hosts, and the nesting pair that rears the cuckoos are the foster parents. These birds incubate the cuckoo eggs along with their own, and when the cuckoo egg hatches they feed the young cuckoo. The foster parents forfeit their own repro ductive success when the nestling cuckoo removes the hosts ‘ eggs or nestlings. Some cuckoo eggs mimic the background color and spot pattern of the eggs of their host, and the eggs of a single species of cuckoo may vary among females, each matching the eggs of a different species of host. Host egg mimicry in cuckoo eggs has been known for a long time. In Europe, the eggs of Common Cuckoo Cuculus canorus often match the eggs of the host nest where they lay, as noted in 1850 (Kunz 1850), described in detail by Baldamus (1853, 1892), and explained as a result of selection by the host, which removes from the nest any eggs unlike its own, by A. Newton (1896). In fact, Newton cited naturalists ‘ knowledge of cuckoo egg mimicry as early as the second century CE.