Living Reference Work Entry

Encyclopedia of Evolutionary Psychological Science

pp 1-2

Date: Latest Version

Egg Rejection

  • William E. FeeneyAffiliated withSchool of Biological Sciences, University of Queensland Email author 


Egg ejection; Nest abandonment


A well-studied defense against avian brood parasitism in which a host “rejects” a brood parasite’s egg – either through physical ejection, burying the egg in the nest lining, or abandoning the nest.


The interactions between avian brood parasites, such as cuckoos or cowbirds, and their hosts have emerged as model systems to study coevolutionary processes under natural conditions. Instead of building a nest and tending their offspring, brood parasites lay their eggs in the nests of other birds and abandon the care of their young to the host. Adult parasites tend to remove or damage host eggs when depositing their own and parasite chicks generally eliminate the rest of the host’s brood after hatching. Consequently, hosts evolve defenses against brood parasites, which select counteradaptations in parasites, further counteradaptations in hosts, and so on. While evidence of reciprocal adaptations and counteradaptations in hosts and ...

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