Experimental increase in eviction load does not impose a growth cost for cuckoo chicks

Abstract

Abstract: Chicks of many avian brood parasites evict their hosts’ eggs within 48 h of hatching. This behavior eliminates competition inside the nest and is beneficial for the fitness of the parasite. Several studies have proposed that this behavior is costly for the parasitic chick and may limit opportunities for cuckoos to exploit hosts with large clutch sizes. We tested whether increased eviction effort was associated with reduced growth in cuckoo chicks by artificially increasing the clutch size of superb fairy-wrens, the main host of the Horsfield’s bronze-cuckoo in Australia. Contrary to theoretical predictions, chicks that evicted a larger number of eggs did not lose mass. Instead, the..