List of bird species in the breeding season of 2020 in the Zhoushan Archipelago, China

List of bird species in the breeding season of 2020 in the Zhoushan Archipelago, China Duorun Wang^{1, #}, Yuhao Zhao^{1, #}, Shupei Tang¹, Xiangxu Liu¹, Wande Li¹, Peng Han¹, Di Zeng¹, Yangheshan Yang¹, Guangpeng Wei¹, Yi Kang¹, Xingfeng Si¹* ¹ Institute of Eco-Chongming (IEC), Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China; ^# These authors contributed equally to this work and should be considered co-first authors; * Corresponding author: Xingfeng Si: [e-mail] <br> We surveyed bird assemblages on study islands in Zhoushan Archipelago in the breeding season of 2020 (from April to June). We setup transects on each island to cover various habitat types for birds except highly urbanized regions (<em>i.e.</em>, cities and towns). For the largest island (Island 1: Zhoushan Island), we set eight transects. For the rest of study islands, we set one, two, or four transects that the number of transects was based on the area and land-use types of study islands. We used Global Positioning System (GPS) to record the position and the length of each transect. The transect length is 2 km on most study islands. However, the transect length is restricted to 1 km for several small islands, as the steep terrain (<em>e.g.</em>, cliffs near the edges) does not allow us to set a 2-km transect. For bird surveys, at least two well-trained surveyors walked at a constant speed (<em>ca</em>. 1.5 km/h) along transects and recorded the identities and abundances of all birds heard and seen. Bird surveys were conducted two hours after sunrise and one hours before sunset, and the overall surveying time was restricted to two hours in each survey. We only conducted bird surveys on days with good weather conditions, excluding heavy raining or strong windy days. All transects were surveyed twice which is the maximum survey effort we can afford due to the large region of the Zhoushan Archipelago, the limited transportations in this region and the relatively short period of the breeding season. Surveyors walked the transects in a random order by inversing the starting point to avoid survey biases.