From the location of these injuries, our experts are placing their bets on beaver. While porcupines can, and do, climb into trees to stay safe from predators while feeding off the bark and twigs, beavers remain grounded. Typically, their gnaw marks are 25- 45 cm high.

Your 20-cm trees aren't big enough to be safe from beavers. They'll tackle trees of almost any size, for a few reasons: to topple them and get at the more succulent twigs and bark of the upper branches; to help build their dams; and (last but not least) because their large, sharp incisors - which grow continuously - can overgrow their jaws if they're not constantly wearing them down.

As for recovery, any wound leaves a tree vulnerable to attack by insects and disease. These trees will already have begun the process of sealing off their injuries. Their success depends on their overall health and vigour.