I realized I also have Brazil's East Asia book and there it's shown that Dark-sided differs from Asian Brown by long primary projection (I hope I am using the right term, it's how much the folded primaries stick out behind the secondaries, not how far along the tail they end) - and thought that our bird has it, but then we looked up many pictures online and Dark-sided has it even longer and the drawings are a tiny bit misleading in this aspect (or other subspecies not relevant for Thailand maybe?), so after a long fight, we give up and concede Asian Brown.
Hainan vs. Blue-and-white I literally don't know! I looked at many pictures of both, it seems the impression really depends on angle, fluffing of feathers ... I am really uncertain. Either one is a new species at least, never saw anything like that.
I put your tern IDs to the observations (you know you could do that yourself
- they make a lot of sense, I don't know why I was so reluctant to put them in the first place. What do you think about this one though -
Roseate Tern (Sterna dougallii) ?
At the moment, this sums up to 188 species - exactly the same number as Malaysia in 2018 and a rather typical result for us "lazy birders" in a medium-sized trip. 53 lifers.
www.mammalwatching.com
