1 Ministry of Education Key Laboratory for Biodiversity Sciences and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing 100875, People's Republic of China.
2 Department of Ornithology, Max Planck Institute for Biological Intelligence, Seewiesen 82319, Germany.
3 Edward Grey Institute, Department of Zoology, University of Oxford, Oxford OX1 3PS, UK.
4 Academy of Forestry Inventory and Planning, National Forestry and Grassland Administration, Beijing 100714, People's Republic of China.
5 School of Ecology and Nature Conservation, Beijing Forestry University, Beijing 100083, People's Republic of China.