Great job hand-held with that big lens. Exposure and sharpness are terrific, as are the light and BG. I'd consider removing a bit on the left; maybe just enough to ditch the yellow glow and have the margin intersect the lower back.
Grace, I am not sure what type of gull it is, but its referred to locally as a 'common' gull. There are variants with red legs and others with black legs and now since you asked I will make a point of finding out more. This one had black legs I think..
Rod I agree with your crop suggestion and almost did this. My main satisfaction with this shot was the sharpness and I think it was a result of an accidental change in technique. I had a (home made) bean bag hanging off my belt and as I squatted down on my RH knee to take this shot I flicked the bag behind me. The bag ended up sitting on top of my right foot and under by behind. I ended up sitting on the bag which was on my RH foot and I was a lot more stable than my normal squatted stance... I will definitely try this again. I had the usual Left hand on lens, left elbow on LH knee out in front of me, right hand on camera and RH elbow in hard against the body...