Because darkness had already set in, I needed the fastest shutter speed possible, which meant that my aperture (which controls the amount of light allowed through the shutter) had to be as large as possible (meaning the smallest possible Av number - it's inverse).
As mentioned in the blurry background post, a low Av number is used to achieve a blurry background effect. The further away the background is from the subject, the blurrier it will be. In this case, the moon was quite a distance behind the bird and therefore quite blurry.
Since I actually wanted the moon to be in focus in my final image, I took a second shot, this time focusing on the moon, ignoring the fact that the bird and tree would come out blurry.
Armed with my two separate images and Photoshop, I copied the in-focus moon from the second shot and pasted it on top of the blurry moon in my first shot with the in-focus bird. I adjusted the levels and changed the hue of the image to a lovely evening blue. The image is named "Awaiting the New Year".
