I don't see any reason to suggest that this is a European Nightjar, which would be an exceptional record in East Asia, rather than Grey Nightjar, which is a regular passage migrant.
The two are similar in plumage, as are many nightjar species, but for me the following features point towards Grey Nightjar:
- Lesser Covert pattern. The coverts show a pattern of buff spots towards the feather tips. European Nightjar should show an obvious white bar across the coverts.
- Scapulars. Photos of European Nightjar typically show a band of black and white feathers across the scapulars, creating a stripe along the side of the mantle. This seems to be lacking in your bird, which instead has black tips to the scapular feathers.
You're lucky to get such a good view of the bird - it's really difficult to see nightjars during the daytime.
European Nightjar:
http://orientalbirdimages.org/se ... Bird_Image_ID=32928
http://orientalbirdimages.org/se ... y_ID=&Location=
Grey Nightjar:
http://orientalbirdimages.org/se ... y_ID=&Location=
