To be even more specific, this is the newly described
bohaii sub species of Black-tailed Godwit.
https://bou.org.uk/blog-zhu-black-tailed-godwit-bohai-bay-subspecies-china/
The
bohaii sub species is our common winter visitor, while our spring passage migrant are sub species
melanurodies, which usually come pass Deep Bay in nice colourful breeding plumage.
Cheers,
Katherine