Yes, I’m sure that motion is a factor also Thomas. The wing tips certainly would be moving faster. However, take a look at these slow moving geese at about the same settings and distance. The first one is not in focus, the second (only a foot or so behind) is in focus, and the third is starting to fade. Clearer in huge pix here: http://farm3.static.flickr.com/2391/206 ... 7e48_o.jpg
The short DOF at f/8 is not necessarily bad. It’s one reason the gulls stand out from their background so well. It does put demands on autofocus however. I’m not pretending to have all the answers here, but I believe that a wider aperture would have shortened the DOF, which I would have chanced if the gulls weren’t zigging around all over, and if I was being more adventurous. If I narrowed the aperture I would get deeper DOF but less light on a gray day. Also the 70-300 VR gets pretty fuzzy as you near F11.
And, cute pooch!