I went whale watching recently, which was an incredible experience. Does anyone know why birds fly above whales when they surface? I forgot to ask, but found it very curious.
Lots of whales hunt fish in groups, and so birds are looking for easy pickings. Probably sardines. The whales coral the fish and drive them to the surface. I’ve seen this often in Monterey Bay in CA. It’s pretty spectacular.
They’re also kinda messy eaters, so often partial fish are left in their wake. Especially easy pickin’s.
when the whale rests on the surface then so do the birds. they even have a name for whales doing that, a La-Z-Bird.
That’s a distractingly plausible typo.
The corrals are made of coral, of course! 
They are drawn in by the whale-song chorale.
Whales are also generally heavily infested with whale lice, externally parasitic crustaceans (not true lice). They typically eat algae from the whale’s surface, or sloughed off skin, and generally don’t harm the whale. I would guess they are also tasty pickings for birds.
I’ve seen this in Alaska on a whale watching boat. In fact, it seemed that the way to get the best pictures of bubble-netting whales breaching was to follow the birds, watch where they dive, and start snapping pics.