Twenty metres up, the canopy looks like a highway. Different shades of green, yellow and grey leaves fuse, creating the illusion of an endless rainforest.
I spent most of 2013 in the canopy of a cloudforest in Colombia, collecting insects and arachnids from inside bromeliads and mosses. I was studying how their availability influences the diet of the Colombian woolly monkey. Despite being one of the largest monkeys in the Americas, this species invests almost one-third of its diet budget foraging for insects. In contrast, large primates such as chimps invest about 4 per cent of their diet budget looking for this sort of protein.
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During the course of my research, I sighted the monkeys from the ground every day, and they likewise saw me following them. In time, I learned to recognise them as individuals. I dreamed of encountering them up in the canopy, on their level. Would they approach me? Or would they run away? These are the sorts of questions that keep a primatologist up at night.
As my year in Colombia drew to a close, I still had not met a monkey among the branches. My dream fizzled away. One December morning, I set off on my final round of ascents, with my colleague Joha on the ground. I paused high in a laurel tree, admiring the infinite green highway for the last time. Suddenly, Joha started shouting. “Look!” she yelled. “The monkeys!”
And there they were, a collection of big-bellied silhouettes, swinging from branch to branch. Their muscular arms and legs were enough to make any bodybuilder jealous – even the females looked as if they spent their spare time lifting weights. Some were hanging from their tails, scratching themselves and scanning their surroundings.
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Then, one of monkeys let out an alarm call. It must have spotted me. In the blink of an eye, six of them hurtled towards my tree. They surrounded me, grabbing and shaking the branches fiercely. My primatologist brain told me they were giving me a warning, and that I needed to be careful, but my body was flooded with delight.
Out of nowhere, a particularly large monkey landed on a thick branch just 5m away. It moved back and forth, frowning at me and baring sharp, yellow canines. It was an older male we had named Cafu, and his dark eyes were fixed on mine. I tried to back away, but my arms and legs went straight to voicemail. I was easy prey.
Then it hit me. I was surrounded only by males. They were creating a distraction so that the females and infants, who were further away, could pass through safely.
Male woolly monkeys are known to be closely related, sharing leadership duties and cooperatively caring for their young. Because of this, troops are not thought to have a dominant alpha male. But given what happened next, I now believe the opposite.
The males started to retreat, glaring back at me now and then. I tried to peer in the direction they were heading. Big mistake. Cafu grabbed an enormous branch and snapped it as if it were a toothpick. He threw it at me, missing my leg by a whisker.
My survival instinct kicked in at last, and I yelled at him. We locked eyes again. He was still showing me who was in charge; I was still at his mercy. Eventually, the other monkeys left and Cafu followed, jumping from tree to tree as if practising parkour. I glanced down at Joha, who looked terrified.
“Are you all right?” she demanded. “Come down!” It took me some time to respond. I was trying to process everything I’d just witnessed.
“Give me a minute,” I finally answered. “I still have to collect the samples.”
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Top image: a common woolly monkey. Credit: Getty