Hi,
A big difference when we get closer huh ? Your shots are a lot better than your Dingo one : your subjects are filling more the frame which looks better.
Your Zebra are over exposed (Shot through the car glass ? ) and the interest of the picture is really limited (sorry....) Try next an original angle or to wait that the zebras are doing something abnormal or at least doing something...
For the Rhino, I beleive that u have the same problem than the Dingo... Push it more to the left of your photo. Try a landscape shot as well (u want to make it look more impressive, bigger.. more powerful that way : Orientate landscape to accentuate the width and size of animals/people, portrait to have "thinner" lines (Models prefer vertical shots...;o)
For the Hippo, same thing... need bigger lens or a nice crop.
For the Lion, the photo is good but no power. I would have center a bit more the lion and tried to have her detached from her background (the piece of wood just behind her head is not very nice...) For big cats wait until they look at you (if possible) or try to have them either totally detached or totally as they were hidding...
Keep going to the zoo, be patient and try different things at different angle.. Ah joy of having a digital camera ;o)
Cheers
