Department of Biology and Food Science;
Hebei Normal University for Nationalities;
Chengde 067000;
China;
Ministry of Education Key Labora-tory for Ecology of Tropical Islands;
College of Life Sciences;
Hainan Normal University;
Haikou 571158;
China;
Hebei Key Laboratory of Wetland Ecology and Conservation;
Hengshui University;
Hengshui 053000;
China;
Cuckoo parasitism; Discordancy; Egg recognition mechanism; Egg rejection; True recognition;