Why don't zombies eat each other? Because their biologics mean either a functioning disposal system or not. And considering a zombie can function without intestines, my money is on not. If they can't stop their hunger, that means the things they gorge on have to go, well, somewhere.
Which brings the obvious point: They can just each other.
And wouldn't sub zero temperatures freeze them in their tracks because of their human frame? Antarctica is clearly the best place to go in the Zambee Apocalypse.
And why in most interpretations does the zombie virus only affect humans? The rest of the animal kingdom seems fine.