One of the reasons I stay out of the “birding arena” is due to a lack of equipment to get it right. With a 300mm lens on a D200 I simply cannot get in close enough to really make it work for me. Cropping to get the image I want is no solution to me.
It takes a lot of practice and experimenting to get a shot like this looking really sharp. A tripod setup and lots of patience will most probably pay off in the end when trying to capture birds. Camera setting will also be critical for different conditions. This one for example, I would imagine that spot metering with spot focus will work best. Trying to isolate the bird and concentrating on getting the focus and exposure perfect on the bird, will be first priority.
In this shot the bird almost disappears in the surrounding leaves. Getting in much closer would reduce the chance of focusing on the surrounding leaves and give you a better chance to get the bird in sharp focus.
Not an easy exercise but worth trying again and again until you get it right.