Polynesian rats eat palm seeds, roots, and sprouts. That's not going to kill a mature tree, but it'll keep trees from replenishing themselves. According to the

Polynesian rats eat palm seeds, roots, and sprouts. That's not going to kill a mature tree, but it'll keep trees from replenishing themselves. According to the theory, when the rats were introduced to Easter Island, where they had no natural predators, the rat population did exactly what you'd expect. Only issue I see with this theory - there were other types of trees on Easter Island, including trees Polynesian rats don't eat.