Hi Dan, You have thought out the composition here placing the bird on the rules of thirds. The jay, however, is the main subject in the image so I personally find it a liitle lost in the frame; but you like this habitat type of image and thats all that really counts. Re long lenses - have you tried a teleconverter?
I like these types of images myself. I like how the brush is 2 different colors and going in opposite directions, adds an interesting element. I think just a bit tighter crop would keep would keep the feel of the image and help the jay show up a bit better,making the image stronger overall? Would possibly clone the one twig running right by the birds face on the left. The image has very pleasing colors.