Egg recognition and rejection ability of Cyanopica cyana against to artificial eggs of Cuculus canorus
Hosts have evolved defensive behavior against parasitic species. In Japan, cuckoo parasitism of Azure-winged magpies (Cyanopica Cyana) started 35 years ago and has spread rapidly with some local magpie populations suffering high rates of parasitism. Interestingly, an increase in the frequency of egg rejection of cuckoo eggs by the azure-winged magpie has occurred in a relatively short time of 10~20 years. This research confirmed Common Cuckoo (Cuculus canorus) brood parasitism of Azure-winged Magpies of Korea and intraspecific brood parasitism in a no brood parasitism situation. Furthermore, we investigated the egg recognition and rejection ability of Azure-winged Magpies for Common Cuckoo model eggs. Field surveys were conducted on two populations at Namyangju city and Yangpyeong-gun in Gyeonggi-do, South Korea from March 2014 to July 2014. and experimented using Common Cuckoo model eggs. randomly input model eggs both laying period and incubation period.
There was no evidence of cuckoo brood parasitism and intraspecific brood parasitism during these surveys. In an artificial brood parasitism experiment, Azure-winged Magpies rejected 24 of 25 nests(total experimental nest). Azure-winged Magpies that detected foreign eggs removed 100% of them out of nests. Most Azure-winged Magpies rejected foreign eggs quickly, within 6 days(83.3%). Despite a lack of interspecific brood parasitism, the azure-winged magpies of Korea have evloved strong egg recognition and rejection ability. While this is a very interesting result, this research did not explain how they evolved such strong egg discrimination and rejection ability. In many research, there is probability of interspecific brood parasitism and intraspecific brood parasitism. Thus, in order to understand the evolutionary source of the Azure-winged Magpie’s host defense, we must conduct an intraspecific brood parasitism experiment.