Effect of host egg color dimorphism on interactions between the vinous‐throated parrotbill (Paradoxornis webbianus) and common cuckoo (Cuculus canorus)

Abstract

To investigate the effect of host egg color dimorphism on the vinous‐throated parrotbill (Paradoxornis webbianus) – common cuckoo (Cuculus canorus) interactions, we monitored breeding nests of vinous‐throated parrotbills, and conducted model egg experiments, using two colors: white and blue. Of the 190 nests examined in this study, cuckoo parasitism occurred at 10 nests (8 blue and 2 white egg clutches, respectively), and only blue cuckoo eggs were found. This frequency was similar to the egg‐color ratio of all host nests found (151 blue and 39 white egg clutches). Vinous‐throated parrotbills showed high rejection rate towards both cuckoo eggs and model ones. There was a significant difference in rejection rates towards mimetic (blue) and non‐mimetic (white) eggs in blue egg clutches. Mimetic eggs put in nests took significantly longer to be rejected than non‐mimetic ones. The most common rejection method used by the hosts was egg ejection (puncture‐ejection). The costs of ejecting non‐mimetic eggs tended...