TPP has several useful rules for tropical field work. Among the most important are don't sit on ant hills and don't step on snakes. Large snakes have rules too; eat anything you can catch. A very large boa was found on one field trip across a 5 foot wide grassy path with both ends hidden by dense vegetation. It was just a 5 foot long cylinder of snake. Who knew which direction it was "going" since it was not moving at all. You leave organisms like that alone. TPP once tripped over an 8 foot boa. It pissed off the snake and shot my adrenaline dangerously high, but neither of us was in any real danger. That is the old primate alarm system that gears you up for fight or flight when scared or startled. And that system exists because us primates are prey to a few big predators. Monkeys are very mobile, very observant, and they don't miss much, so big snakes don't catch monkeys very often, but if the monkey makes a "misnake", it will probably be their last. TPP has seen a big boa consume a sloth of comparable size, but monkeys are considerably faster.