Gregor looked up just in time to see some kind of beast fly right over him and disappear into the distance. It actually gave him pause. He stopped in the middle of the trail and looked curiously down at the water skins. The Serpent Riders carried a potent hallucinogenic soup called, appropriately, Serpent Venom that they drank before a dangerous hunt that they said allowed them to perceive the true shape of their prey. He shook the skin and looked around at the jungle. He didn't feel high or particularly perceptive of the spiritual side of things, but that just meant that whatever just jumped over his head was real enough that he could see it sober. 

"Island mysteries," he said to nobody. "What can you do?" He kept walking. Slightly faster now.