If you've ever been in a fast food restuarant parking lot within 40 miles of the shore, you know that gulls aren't known to be shy. This one sat there for about 15 seconds and flew off when the whale started submerging. They are looking for any small fish that might escape while the humpback is straining it's mouthful of fish and water through it's baleen. They are also seen to try to to snatch fish from inside an open mouth, a little more risky. The humpback's throat is only as big around as a grapefruit, so gulls can't be swallowed, they are too big. The rare one that ends up inside is usually spit out, not likely in very good shape, though.