Funding for this research was provided by:
SHAN SHUI Conservation Center, Beijing
Received: 29 December 2020
Accepted: 23 February 2021
First Online: 6 March 2021
: This article does not contain any studies with human participants performed by any of the authors. The experiments comply with the current laws of China. Bird capturing and tagging was approved by Beijing Gardening and Greening Bureau.
: Not applicable.
: The authors declare that they have no competing interests.