Mystery Bird: Sandwich Tern, Sterna sandvicensis

In the words of Spike Milligan:

Mother tern to baby tern
"Would you like a brother?"
Baby tern to mother tern
"Yes - one good tern deserves another".

Heh. "One good tern." This guy (or gal) certainly is good at turning mid-air.

I'm having a hard time deciding if I am seeing a yellow tip on the bill. If I am, I'd call this a sandwich tern. If not, I guess either common or Forster's?

The cap looks like "breeding plumage" in its extent for any of them, but it looks from Sibley like I would expect a red bill by May for common or Forster's. So I guess I'll go with sandwich for my guess.

The lovely Sandwich tern's unique:
It has a yellow-tipped black beak.
Its cap is also sooty black.
This one's flying on its back.

I was too hasty with my verse:
Only its head is in reverse.

I guess one could say that its head is...terned upside down.

I'd go with Sandwich Tern too, based on the yellow tip at the bill.

There were Arctic Terns migrating northward up the Ottawa River last week. Naturally, none flew by on the day I drove out to see them.

I agree it's a sandwich tern. Is it defending itself?

I'd say it was shaking after coming up from a dive (unsuccessful, by the looks of it)...

I'd say it was shaking after coming up from a dive (unsuccessful, by the looks of it)...

I wondered about that (you can see a few drops of water) but when I've seen birds shake themselves they normally keep their head stable and shake their body.

Diving underwater (with rising bubbles)?