Potential cuckoo hosts have similar egg rejection rates to parasitized host species

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Avian Research Open Access

RESEARCH

Potential cuckoo hosts have similar egg rejection rates to parasitized host species Tingting Yi1,2, Yue‑Hua Sun2* and Wei Liang1* 

Abstract  Background:  Thrush species are rarely parasitized by cuckoos, but many have a strong egg recognition ability. To date, there is a limited understanding of the relationship between host egg rejection and cuckoo parasitism rate. Methods:  By using egg experiments in the field, we compared egg rejection between two non-parasitized potential host species and two parasitized hosts of cuckoos in the same region. Results:  The White-bellied Redstart (Luscinia phoenicuroides), a host of the Common Cuckoo (Cuculus canorus), rejected 66.6% of blue model eggs; the Elliot’s Laughingthrush (Trochalopteron elliotii), a host of the Large Hawk Cuckoo (Hierococcyx sparverioides), rejected 25% of blue model eggs and 46.1% of white model eggs; and the Chestnut Thrush (Turdus rubrocanus) and the Chinese Thrush (T. mupinensis), in which cuckoo parasitism has not been recorded, rejected 41.1 and 83.3% of blue model eggs, respectively. There were no significant differences in the egg rejection among them, although the Chinese Thrush showed the highest rate of egg rejection. Conclusions:  This study indicates that the egg recognition ability of cuckoo hosts has no correlation with the actual parasitism rate of cuckoos. We suggest that the egg recognition ability of the two potential host species may have been retained from a parasitic history with the cuckoo, while the two common host species have developed their egg rejection abilities due to current parasitism pressure. In addition, our study highlights the importance of the multicuckoo parasite system for better understanding the selection pressure of parasitism on the evolution of host egg recognition abilities. Keywords:  Anti-parasitic strategy, Cuckoo parasitism, Egg rejection, Large Hawk Cuckoo, Potential host Background Brood parasitism is a special breeding behavior of some cuckoo species where, instead of building their own nests, cuckoos lay their eggs in the nests of host birds, which hatch their eggs and raise their chicks (Payne 1977). Host birds pay a high reproductive cost for this. During parasitism, cuckoos take 1–2 eggs away from the host. After hatching, cuckoo chicks sometimes remove eggs or other chicks from the nest, and often get more food due to their *Correspondence: [email protected]; [email protected] 1 Ministry of Education Key Laboratory for Ecology of Tropical Islands, College of Life Sciences, Hainan Normal University, Haikou 571158, China 2 Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China

superior physicality and begging sounds, thus defeating other host chicks in the nest (Davies 2000). Under this selection pressure hosts develop anti-parasitic strategies to prevent cuckoo parasitism at all breeding stages (Davies 2011; Soler 2014a). At the egg stage, many hosts recognize and reject parasitic