Fly fishing?

On the way to the post office today, I noticed a few Bonaparte's Gulls (Chroicocephalus philadelphia) near shore at Spud Point (along the west side of Bodega Harbor).

I stopped briefly to take a look and was intrigued to see that they appeared to be catching flying insects.  While sitting on the water, they would paddle forward and then snatch suddenly at something above the surface of the water.  I couldn't see the insects, but the behavior and situation made me wonder if the gulls were flushing and catching flies?

Here are a few pictures: