I'm glad I'm not alone being unable to beat it xD I am inclined to program a solver to find out if it's possible ha! I'll let you know if I did it.
The game is fantastic, a true head scratcher with very beautiful art. It works flawlessly and also has a nice positive message. It's one of my fav themes: ecosystem restoring. One of the prototypes I'm putting some time on is exactly that, animals recovering destroyed ecosystems :)
Really appreciated this game, good job.