anjz said:
A man saw my camera, walked up to me, and commissioned me to take sea gull shots for his new business. I had my D7000 and a 50 1.4G and that's all.
Very impressive shots, Anjz! Shots #1, #3, #4 are amazing. Incredible lighting, spot-on exposure, and great-looking skies. The motion-blur on #4 is perfect. The angles are simply the best!
AF Nikkor 80-400mm f/4.5-5.6G VR Samples:
As Anjz has shown above, you don't necessarily need a zillion-millimeter lens to get great shots (well, at least of plentiful and easy-to-bait seagulls, anyway). Although, I'm by no means an experienced bird photographer, I thought I'd post a couple of thoughts anyway.
I went out by the ocean to shoot some gulls last year to try out my then, new, AF 80-400mm lens. Even with a 400mm lens on a DX body, those damn birds are still really far away. But since my chosen location was at a tide pool, I was able to wade out to them and shoot them pretty close-up. Though not necessarily specific to birds, here's all I could think of to suggest:
1. If shooting water foul, pay attention to what's reflected in the water. The prettier the sky and your surroundings, the prettier the water.
2. Try to shoot with clouds in the sky. Images of birds in-flight with a dramatic, cloud-filled sky often look a lot prettier than with a solid white-gray sky for a background.
Both images below were taken at the exact same location, at about the same time of day, but a couple weeks apart. I wanted to show these to illustrate the dramatic differences in results due to changing lighting and weather conditions. The first day I shot was a sunny day, but there were no clouds in the sky whatsoever. Nevertheless, at least the sky was blue, and both the warm, earth-colored cliffs nearby, and the blue sky above, made for a very colorful reflection:

Nikon D90
AF Nikkor 80-400mm f/4.6-5.6G VR
[Uncorrected image]
The second time I went out, it was overcast and gray (it was actually raining)--every shot lacked contrast and was virtually completely void of color. You'll notice that the dull, white-gray, featureless sky was faithfully reflected in the water, with similarly dull-looking results:

Nikon D90
AF Nikkor 80-400mm f/4.6-5.6G VR
[Uncorrected image]
Oh, I forgot to answer the most-asked question about the 80-400mm: "Is the 80-400mm's non-AFS focusing too slow for shooting birds in-flight?" Yes! But, if you pre-focus, and track accurately, it can certainly be done. However, framing accurately, way out at 400mm (600mm-equivalent on DX), without the benefit of a gimbal head, is actually probably the greater challenge. It's even more of a challenge when the VR "re-adjusts" your frame for you!