Cuckoo brood parasitism is a remarkable evolutionary strategy with significant welfare consequences for host birds who raise cuckoo chicks at the expense of their own offspring.
Brood parasitism has complex welfare implications. Host parents experience significant energetic cost raising a cuckoo chick that may be four times larger than themselves, and their own genetic offspring are destroyed. The host parents show behavioural responses to cuckoo chicks that are not obviously distinguishable from responses to their own offspring, suggesting they cannot readily detect the deception. The welfare implications for individual host birds — loss of reproductive success, energy expenditure — are real even if the hosts lack the cognitive capacity to grieve specific offspring. This is a natural evolutionary relationship, but habitat management that supports both cuckoos and their hosts benefits all involved.