Avian Brood Parasitism and Host Coevolution

Avian brood parasitism is an interspecific reproductive strategy in which parasites deposit eggs in the nests of hosts, transferring the burdens of incubation and chick rearing while imposing significant fitness costs on the host. This interaction has spurred a complex arms race: parasites refine egg mimicry, laying behaviour and host‐specific races, whilst hosts evolve egg rejection, nest defence, sensory discrimination and even cooperative mobbing of intruders. Coevolutionary processes unfold across behavioural, morphological and genetic dimensions, encompassing maternal inheritance of egg-colour traits, disruptive selection on egg phenotypes and adaptive plasticity in host defences. Insights from this system illuminate rapid evolution in natural populations, inform conservation strategies for vulnerable hosts, and serve as a model for understanding reciprocal selection in ecological communities.

Research from Nature Portfolio

Recent studies have shown that reciprocal selection—known as chase-away evolution—can maintain imperfect egg mimicry over multiple decades as parasites evolve resemblance to host eggs while hosts shift away from parasite phenotypes. Field experiments have revealed that hosts balance two opposing adaptations—egg rejection and retrieval—by rejecting non-mimetic eggs under high parasitism pressure yet retrieving or tolerating closely mimetic eggs, demonstrating flexible behavioural strategies governed by parasitism risk and mimic fidelity. Further research indicates that even in the non-breeding season, sedentary passerines recognise and respond to cuckoo calls, suggesting an extension of anti-parasite vigilance beyond the nesting period and underscoring year-round coevolutionary preparedness.

Avian Brood Parasitism and Host Coevolution publication trend

The graph below shows the total number of articles in avian brood parasitism and host coevolution across all publications each year (not limited to Nature Index journals).

Technical terms

Avian brood parasitism: A reproductive strategy whereby one bird species lays eggs in the nest of another, outsourcing parental care.

Coevolution: Reciprocal evolutionary change in interacting species, each exerting selection pressures on the other.

Egg mimicry: Evolution of parasite egg appearance to closely resemble host eggs and evade detection.

Chase-away evolution: A model of antagonistic coevolution in which host defences and parasite counter-defences escalate, maintaining imperfect mimicry.

Egg rejection: Host behaviour involving removal or destruction of foreign eggs from the nest.

Polymorphism: Presence of multiple distinct phenotypes, such as differing egg colours, within a single population.

References

1. Chase-away evolution maintains imperfect mimicry in a brood parasite–host system despite rapid evolution of mimics. Nature Ecology & Evolution (2023).
2. Dynamics of evolutionary succession and coordination between opposite adaptations in cuckoo hosts under antagonistic coevolution. Communications Biology (2024).
3. Reactions of wintering passerines to male calls of the European cuckoo Cuculus canorus. Scientific Reports (2024).
4. Importance of cooperation: How host nest defenses effectively prevent brood parasitism from the cuckoos. iScience (2023).
5. Deep Learning-Based Parasitic Egg Identification From a Slender-Billed Gull’s Nest. IEEE Access (2023).
6. Egg discrimination along a gradient of natural variation in eggshell coloration. Proceedings of the Royal Society B (2017).
7. Coevolution in Action: Disruptive Selection on Egg Colour in an Avian Brood Parasite and Its Host. PLOS ONE (2010).
8. Ancient origin and maternal inheritance of blue cuckoo eggs. Nature Communications (2016).