You cannot get shots like the one in today's post without getting down on your knees at the very least, unless you are very young. Another advantage of getting low is stability, if you don't have a tripod, but you need more stability, getting down on your knees or flat on your chest may be one way to get it. Keep in mind that image stabilization is best used for low shutter speeds, but when you get to 1/500s or faster it can actually lower the quality of your image, because the IS/VR cannot keep up and thus never fully stabilize, causing softness in your image. High shutter speeds may deal with subject motion, but if you are using a super telephoto lens, as you would for bird photography in most cases, then even the slightest amount of camera shake can soften your image. We need to get back to getting low though.
So one reason to get low is stability, another is for a different way of looking at your subject. What other reasons are there for getting low? Emphasizing angels, or height of your subject, are just a few. In the image sample below you can see that angels and the height of the subject are emphasized by the fact that I got low, rather than standing.
Look Up, Modern Architecture
By getting down you can show the viewers of your image the sense of height that your subject gave you, in fact you can make the subject look taller than it is in reality. This is especially true when you are using a wide angel lens. The sample image was taken at 12mm, which allowed me to get more of the subject into the image. So when the combination of a wide angel lens and a low stance, you can emphasize the distance even more. A telephoto lens would not be able to get the same angel, and the size of the subject would appear more compressed and thus loose the sense of height.