Daurian redstart Phoenicurus auroreus is a host for the common cuckoo Cuculus canorus during the second, but not the first cultch

Abstract

Background: Coevolution in cavity-nesting host-cuckoo systems may differ from those in open-nesting hosts due to unique conditions in cavity nests. We investigated brood parasitism in Daurian redstarts ( Phoenicurus auroreus ), a regular cavity-nesting host of common cuckoos ( Cuculus canorus ).Results: A total of 15.6% ( n =358) of host nests were parasitized by cuckoos. Cuckoos were highly successful in parasitizing Daurian redstart nests: nearly all cuckoo eggs were laid in the nest cup, and all cuckoo chicks evicted all host offspring. However, egg ejection by Daurian redstarts was egg morph specific, i.e. hosts laying white eggs ejected most real cuckoo eggs, while hosts laying blue eggs did not eject any. In contrast, hosts ejected most mimetic cuckoo eggs. Moreover, most Daurian redstarts moved to nearby villages during the second breeding attempts, where the risk of cuckoo parasitism was reduced. Parasitism only occurred during the second breeding attempt, since cuckoos had not yet arrived at the breeding grounds when hosts started to lay their first clutches, which may indicate a novel and unique anti-parasite defense, advancing breeding time of hosts.Conclusions: Our results suggest that Daurian redstarts suffer from high risk of cuckoo parasitism showing more intense egg ejection while building nests closer to human habitation in the second clutch. This suggests that cavity-nesting hosts may show adaptations to brood parasites that differ from those of open-nesting hosts.

Brood parasitism and egg recognition in three bunting hosts of the cuckoos

“…During parasitism, the common cuckoo may mistakenly lay its parasitic eggs in the nest of its host's 'neighbour' under the pressure of the host's nest defences. The grey bushchat is the dominant species in the study area and has a large population, with its nesting population well distributed (Zhong, 2020). The grey bushchat nests on open bowlshaped nests on the ground, similarly to the three bunting species in the present study.…”

“…In the study area, the common cuckoo that laid such eggs is known to primarily parasitise the nests of grey bushchats as their primary host (Zhong, 2020). The egg phenotype of the common cuckoo, pale blue eggs, was highly mimetic of that of the grey bushchat (Zhong, 2020). The two parasitic eggs found in this study were of this same phenotype, indicating that they were both laid by common cuckoos that primarily parasitise the nests of grey bushchats.…”

“…In this study, the results showed a very low rate of parasitism in all three species of buntings, and one each of yellow-throated bunting nest and south rock bunting nest were found to be parasitised with pure pale blue eggs that did not match the phenotype of the host eggs. In the study area, the common cuckoo that laid such eggs is known to primarily parasitise the nests of grey bushchats as their primary host (Zhong, 2020). The egg phenotype of the common cuckoo, pale blue eggs, was highly mimetic of that of the grey bushchat (Zhong, 2020).…”

“…In this study, we investigated the parasitism of these three species of buntings by the common cuckoo in the same area. The main common cuckoo population in the study area uses the grey bushchat (Saxicola ferreus) as its primary host, laying eggs of a blue phenotype (Zhong, 2020), which does not mimic the eggs of the three species of buntings. Model eggs have been used in many previous studies (e.g.…”