One big thing which i havnt mentioned in that Image details is, that its NOT a single image. Any photographer will be able to identify that fact immediately, as both the subjects are in focus, but not in the same plane. 

So, this is two images merged to get both the buzzards in-focus. 

Making of this image, starts right from the time you see these two through the view-finder of your camera. You know for absolutely that you cant get both the birds in-focus. But you imagine that to be the end-result you want to achieve. in that split-second, you have to keep the end-result in the frame, and click two images, one with the bird in the front in-focus, and the other with the bird in the behind in-focus. And for all these, you just have less than a second, as you can never guarantee the positions of these two birds to be the same for long. So, you make that decision, and act quickly by focusing on one, click, focus on the other one, click. And all these when you're standing on a jeep, zooming your lens to the max of 500mm, and holding it in hand.

All these efforts are, just for the pic you've imagined that instant. And once you get those pic to the computer, all you need is little skill/knowledge on your favorite Image Editing Software (for me, ofcourse, Photoshop).