Action Shots. -Gulls in Harbour

I went down to Dunbar harbour this morning to try out how my new camera deals with birds in flight. I though I was actually doing quite well shooting gulls against the harbour wall but when I came to check the shots over in post-processing the camera had been focussing on the harbour wall and the aperture was sufficient to make the birds look as though they were in close focus. However, here is one where the focus is spot on.