On top of what Kwigg said, I got screwed on a few attempts because I saw two of the same animal near each other, but only one of them actually counts. Even if I did memorize every position, I'm not sure I could beat it in the time allotted, it seems very tight.
Maybe instead of just failing as soon as the water touches one of them, make it so they flee to higher ground? And probably close off more and more of the map as the floodwaters rise.