From time to time I like to post images that are not my best. Why? To show that all photographers need to be vigilant in order to create more interesting images, no matter how experienced they are.
So what is not good about this image? First, the lighting could have been better. This scene with a Downy Woodpecker is a good example of a situation where fill flash would be helpful. I don't tend to use a flash for wildlife work, because it can bother some subjects, and I don't have a flash extender (Better Beamer).
Some viewers might question that position of the subject, which is in the centre of the frame, but I do not see that as a problem in this case. The rule of thirds is helpful, but not something that needs to be observed at all times. The objects around the subject create a situation where central framing is acceptable.
Another element observers may notice is the background, which is extremely busy. All the tree branches in the background are somewhat disruptive, and can draw the eye away from the subject. Having a lens with a wide aperture is sometimes helpful, but that can also cause a decrease depth of field, which may not be desirable. While it is not always possible to eliminate all distractions in an image, finding the same bird in a scene where those items are not present would create a cleaner, more enjoyable image.
Wildlife photography creates an issue that few other types must deal with, a total lack of control over the location of the subject. That lack of control is what drives wildlife photographers to photograph the same creatures over and over again, because no image is ever perfect.