Realization that precautions are necessary
Because beavers are known to be animals that are territorial, Jim reasoned that if it were a beaver, it would most likely be very protective of its territory because of the fact that beavers are known to be animals that are territorial. Even though he had a hunch that it wasn’t a massive beaver, he still needed to be on guard against the possibility that it could get loose and eat him like a salad if it so chose.
This meant that he had to keep his distance from the animal. Even though he had a hunch that it wasn’t a massive beaver, he still needed to be on the lookout in case it broke free of its confinement and went on the prowl. Should something like that take place, he will be in a great deal of trouble as a direct consequence of it.