I did quite a few primate surveys during my time in Peru. One afternoon, there were 4 or 5 of us including the guide out gathering data. We hadn't seen any monkeys yet, but suddenly the guide told us to stand still and be very quiet. We assumed he had spotted some monkeys, so we looked around trying to find them. In the next minute that followed 15 or so coatis jumped out of a tree a few meters in front of us. It was pretty amazing because we were so close and could see them really clearly. We didn't spot any primates during the survey but even during surveys where you didn't always find what you were looking for, something great would come out of it.