Hi Rob..At that distance, I would't have taken the shot. The bird is too far away, and due to the high ISO setting, there was no way you were going to get a clean image after cropping as much as you did. If the bird was closer, the first thing I would do was move to my left, so the out of focus leaf didn't cover part of the perch and more importantly the birds tail. It's all about getting closer to the bird, the closer you get, the more detail you will capture. What you need to do is, if possible, use a set up with some feeders, and nice perches for the birds to land on. Once these chickadees come to the feeders you should get close enough to them. It is best to get good lighting conditions where the birds will be well lit. That way you can use a faster shutter speed(1/800 or faster), an aperture of f/5.6, then set your ISO accordingly. If the light is good, this should keep you at a lower ISO, say 640 or 800, but watch your meter and make sure you don't under or over expose. If you use manual exposure, then you can change the settings for the lighting conditions at the time. As long as you keep your shutter speed at 1/800 or faster, your aperture at f/5.6 or f/6.3, then, generally speaking, that should get you off and running. Always try and keep the sun behind you. Soft light is best, so early morning or late evening when there is good sunlight. A too bright, strong sun, will be too harsh, and this will show on the image. It is not always easy to get a good photograph of a bird, think of the background as well. You don't want anything distracting in the background. Try to get a good POV, if the bird is on the ground, get as low as possible, so you will be on the same level as the bird. Once you have mastered the exposure, and fieldcraft, then you will gain more confidence, and your images will be better. There is an abundance of information on BPN, where you will pick up lots of tips on how to photograph birds. Keep practising and it will all come together.
Will