Unfortunately for Dylan, the sound and motion he heard wasn't just rodents.  As he got closer, he heard what was clearly a small group of people searching the perimeter of the camp.  He was too far away from them to hear what they were saying clearly, or tell just how many were in the group.  After a few moments, they split up, and he was able to see a group of three heading into the camp, picking their way along until they came to one of the devices the workers had put up.  The second group, just two people, continued to search around the perimeter.  So far, none of them had noticed Dylan.