In Hatchet, how does Brian put clues together to figure out the identity of the animal he hears in the night, and how does he benefit from figuring out what it was doing? Find the relevant textual evidence.

In Hatchet, Brian has a few encounters with animals in the night. One such encounter occurs on the night after Brian was able to successfully build a fire. He hears a sound like something being dragged over the sand, but it is too dark for him to see what is making the sound. He then hears the sound of something moving in the water of the lake. After sleeping for a while longer, Brain wakes and sees the tracks left by the creature. Brian uses clues to determine the animal that could have left the tracks. For example, he notices that the animal must have had a "flat dragging bottom" with marks like claws on either side. He notices that the trail left by the animal leads to a pile of sand, then back to the water. Brian realizes there must be a purpose to the pile of sand. After some digging, he discovers eggs and realizes the animal must have been a turtle. Brian benefits from his perseverance because he now has the eggs as food.