Roost and environment of mixed-species colony of Corvidae in winter in urban areas of Zhengzhou

Mixed species colony of Corvidae, including Corvus macrorhynchus, C.frugilegus, C.torquatus, C.monedula and C.monedula dauuricus,has roosted urban areas of Zhengzhou in winters successively. The species and population of colony have been increasing year after year. The population of the colony has reached 10 000. The colony has migrated each year winter from November 1998 to January 2004 (reaching Zhengzhou in November each year and leaving Zhengzhou in March next year) and moved habitat 3 times in 6 year. ...