Welcome to the forum If you are going to pursue wildlife photography to any extent in a zoo, o rin the wild, then you might want to think a bit about your approach. Generally it is not considered acceptable to crop off appendages like the elephants trunk. You also want to get as much of the animal in your image as possible, unlike the third one. If you are going for head shots (portraits) the you need the entire head and it needs to be all in focus, unlike the first one. I do not want to sound to severe, but you asked for C&C. You might want to Google animal photography and look for some of the work of folks like Art Wolfe, Andy Rouse, Andy Biggs, John Marriott, Art Morris, Laurie Excell, Wayne Lynch, Piper Mackay and George Lepp ( and a host of others). Study their imagery with a critical eye and decide which images you like and why, and which you don't like and why. I don't suggest that you copy these folks, but reviewing their images will definitley give you some ideas on how the pros are doing it. My 0.02¢ FWIW.
WesternGuy