Data from: Rearing a virulent common cuckoo is not extra costly for its only cavity-nesting host
Samaš, Peter et al. (2018), Data from: Rearing a virulent common cuckoo is not extra costly for its only cavity-nesting host, Dryad, Dataset, https://doi.org/10.5061/dryad.665117s
Virulent brood parasites refrain from arduous parental care, often kill host progeny and inflict rearing costs upon their hosts. Quantifying the magnitude of such costs across the whole period of care (from incubation through to parasite fledgling independence) is essential for understanding the selection pressures on hosts to evolve antiparasitic defences. Despite the central importance of such costs for our understanding of co-evolutionary dynamics, they have not yet been comprehensively quantified in any host of any avian brood parasite. We quantified parasite rearing costs in common redstarts Phoenicurus phoenicurus raising either parasitic common cuckoo Cuculus canorus or their own chicks throughout the complete breeding cycle and used multiple cost parameters for each breeding stage: incubation, brooding and feeding effort; length of parental/host care; parent/host body condition and the heterophil/lymphocyte ratio (stress level indicator). Surprisingly and contrary to traditional assumptions, rearing the parasite per se was not associated with overall higher physiological or physical costs to hosts above the natural levels imposed by efforts to rear their own progeny. The low parasite-rearing costs imposed on hosts may in part explain the low levels of known host counter-defences in this unusually frequently parasitised cuckoo host.