This is cool, the mammoths behaving as individuals as they try to follow each other or encounter other entities is an interesting idea, and I like how everything has these little reactions to what happens around them. It's fun smacking the dragons into the water!
My main feedback is that the levels get a bit long towards the end without it becoming more interesting. I got the impression that sometimes the dragons get woken up without me doing anything, so I feel I don't have a chance to complete the level rescuing all mammoths, which is fine, but it gives me one less thing to strive for in a long level.