|A good shot, resulting in a good score. I'd give it a 6. The red color in the mouth is the highlight of the image. So why didn't it top 6? There are no major problems, but an accumulation of little details cost you about half a point...
Shooting a 'common' animal automatically puts you at a disadvantage ribbon-wise. Sure, it's do-able, but your focus has to be razor sharp, and you need a great expression and/or beautiful light (look at the cat shots in my favorites).
It looks like you shot this on a cloudy day, so you pushed the ISO a little higher to compensate for the low light. Fair enough, but the lighting is still kinda' flat, and the higher ISO yields grain in the background. Your focus is decent, but the only crisp detail is just above the right leg- maybe you had to crop a lot, didn't use a tripod or didn't use Bicubic Sharper when scaling down. With advanced editing, you certainly could have cleaned up the spot on the railing. Lastly (and probably most importantly) the seagull has it's mouth open, but that's about it- the expression is still rather blank, and the centered composition is completely static. If you couldn't get another shot, you could burn and dodge some subtle shading around the eye for a "meaner" expression, and maybe a diagonal or off-centered crop would make the image more dynamic.