Attached Link: http://www.rrives.com/RivesXmas04/slides/CRW_1558.html

I too am working on nature shots, but have had little opportunity. The images look slightly soft, could come from camera shake. Are you using a tripod? 1/180 of a sec. is borderline shutter speed for hand holding the lens on your 1st image. Try bumping the ISO up to 800. The general rule is 1/focal length. So for a 200mm you need to use 1/200th shutter speed, and if you shot digital don't forget to factor in fv crop. So on my DRebel that would be closer to 1/350. I have yet captured a bird shot that I really like. I really like the 3rd shot, love the color and lighting. I think for bird shots, especially the small birds as in your example you need a longer lens. I use 75-300 and find that I need more. The link is the best bird shot I have been able to take, after many attempts.