Also check sharpness, none of them seem that sharp (or look like a soft image that has been over sharpened) but that might just be a combination of my iPad and downsizing.
Don't underestimate how fast the shutter speed has to be. People talk about the inverse of the focal length but you need to adjust for the crop factor and your own hands. A 300mm lens on canon and you would want 1/500th at a minimum and I would probably push for 1/800th or even faster.
Yeah, and Another reason for fast shutter speeds is that small birds can twitch and move very very fast , I shot a little finch last week at around 1/500 and I got a bit of motion blur from its little fidgety movements