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Escalation of a coevolutionary arms race through host rejection of brood parasitic young

Nature volume 422, pages 157160 (13 March 2003) | Download Citation



Cuckoo nestlings that evict all other young from the nest soon after hatching impose a high reproductive cost on their hosts1. In defence, hosts have coevolved strategies to prevent brood parasitism. Puzzlingly, they do not extend beyond the egg stage2,3,4,5. Thus, hosts adept at recognizing foreign eggs remain vulnerable to exploitation by cuckoo nestlings6,7. Here we show that the breach of host egg defences by cuckoos creates a new stage in the coevolutionary cycle. We found that defences used during the egg-laying period by host superb fairy-wrens (Malurus cyaneus) are easily evaded by the Horsfield's bronze-cuckoo (Chrysococcyx basalis), a specialist fairy-wren brood parasite. However, although hosts never deserted their own broods, they later abandoned 40% of nests containing a lone Horsfield's bronze-cuckoo nestling, and 100% of nests with a lone shining bronze-cuckoo nestling (Chrysococcyx lucidus), an occasional fairy-wren brood parasite. Our experiments demonstrate that host discrimination against evictor-cuckoo nestlings is possible, and suggest that it has selected for the evolution of nestling mimicry in bronze-cuckoos.

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N.E.L. was supported by an Australian Research Council Australian Postdoctoral Fellowship. R.M.K. was supported by a Royal Society Dorothy Hodgkin Research Fellowship and a Royal Society University Research Fellowship. Spectrophotometric equipment was purchased with a BBSRC grant. We thank Environment Australia for allowing us to work at Campbell Park; S. Butchart, A. Cockburn, N. Davies, M. Hall, G. Maurer, J. Madden, N. Macgregor and A. Peters for assistance in the field; A. Cockburn for statistical advice; and M. de la Brooke, A. Cockburn, N. Davies, R. Heinsohn, C. Hinde, A. Lotem, R. Magrath and S. Rothstein for comments on the manuscript.

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  1. *School of Botany and Zoology, Australian National University, Canberra, Australian Capital Territory 0200, Australia

    • Naomi E. Langmore
  2. †School of Biological Sciences, University of Bristol, Woodland Road, Clifton, Bristol, BS8 1UG, UK

    • Sarah Hunt
  3. ‡Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK

    • Rebecca M. Kilner


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Competing interests

The authors declare that they have no competing financial interests.

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Correspondence to Naomi E. Langmore.

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