China is located in the eastern part of the Eurasian continent, with a large north–south range, resulting in a large temperature difference. Wild birds migrate two times annually along with the north–south range, including eastern, central and western routes in China. Wild birds are reported to carry influenza viruses from multiple sources, causing the virus to spread across a wide range of regions, which present great challenges for the prevention and control of avian influenza viruses (AIVs)