Background: Chicks of virulent brood parasitic birds eliminate their nestmates and avoid costly competition for foster
parental care. Yet, efforts to evict nest contents by the blind and naked common cuckoo Cuculus canorus hatchling are
counterintuitive as both adult parasites and large older cuckoo chicks appear to be better suited to tossing the eggs and
young of the foster parents.
Methodology/Principal Findings: Here we show experimentally that egg tossing imposed a recoverable growth cost of
mass gain in common cuckoo chicks during the nestling period in nests of great reed warbler Acrocephalus arundinaceus
hosts. Growth rates of skeletal traits and morphological variables involved in the solicitation of foster parental care remained
similar between evictor and non-evictor chicks throughout development. We also detected no increase in predation rates
for evicting nests, suggesting that egg tossing behavior by common cuckoo hatchlings does not increase the
conspicuousness of nests.
Conclusion: The temporary growth cost of egg eviction by common cuckoo hatchlings is the result of constraints imposed
by rejecter host adults and competitive nestmates on the timing and mechanism of parasite virulence.
Anderson, M. G., Moskát, C., Bán, M., Grim, T., Cassey, P., & Hauber, M. E. (2009). Egg Eviction Imposes a Recoverable Cost of Virulence in Chicks of a Brood Parasite. Plos One, 4(11), A67-A73. doi: 10.1371/journal.pone.0007725
2009 Anderson et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.