Your shutter speed was 1/50 sec. That's way too slow for taking a photo at 55mm (full zoom on your lens), and it's too slow to photograph an animal at anyway. When stuff is moving around (and to combat camera shake), you really need to be more in the range of 1/200 sec or above. When I'm taking animal photos (which I do a lot) 1/200 is the absolute lowest I will go. I'm usually more in the neighborhood of 1/500 or more if there is movement.
The shot is blurry because of camera shake, not because it wasn't in focus. Also, I'm guessing you did crops on all of these? Do yourself a favor and pick up a cheap telephoto. That way, you can take advantage of your camera's actual resolution, rather than shooting and cropping.