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Written by and Photos courtesy of Caitlin Andrews

I recently came across a stack of my old elementary school papers, and, on one of them, my seven-year-old self wrote that I wanted to be a primatologist when I grew up. Fourteen years later, I’m here in Mexico working on my undergraduate thesis on spider monkey behavior, and I like to think that I’ve fulfilled a little piece of that dream that I set my sights on so many years ago. To this day, people often ask me what initially drew me to primates, in particular. For many people, primates are so appealing because they are so like us; there’s something in their eyes that speaks to our souls, revealing some truth about who we are as humans and where we came from. But, I think what I have always found so remarkable about primates is the exact opposite: how, despite all of their similarities to us, there is still something so separate, so beautifully wild about them.


Mexico - Caitlin Andrews 2


Over the years, I like to think that I’ve reclassified myself as an all-around zoologist, rather than solely a primatologist. In the last three years, I have been working towards my undergraduate degree in Organismic and Evolutionary Biology at Harvard, where I’ve had the opportunity to work with lizards, parrots, dogs, and captive gorillas. Each of these experiences has taught me something different and surprising about how animals think and interact with their environment. But, heading into my fourth and final year—during which I would have to complete a thesis project—I knew that I wanted to return to my first love: primates. OpWall had already been on my radar for a few years, but I had never made the plunge to sign up for an expedition. When I found out about the spider monkey behavior project in Mexico’s Calakmul Biosphere Reserve, it seemed like a perfect match.

Nearly ten months after I began my initial email conversation with Dr. Kathy Slater (OpWall Senior Scientist), I’m here in Mexico, with two months of monkey-watching behind me and an autumn of data analysis ahead. Every day this summer has been exciting and unpredictable. Alongside three other thesis students and our two guides, Alex and Samuel, I wake up at 5am each morning and head out into the forest, where we find the monkeys, still asleep in their sleep trees. When the monkeys finally begin to stir and we can identify each individual’s age and sex, we begin our data collection. Every ten minutes, we note what each individual is doing (resting, feeding, socializing, etc.), the group’s GPS location, and the type of habitat they are in (based on tree height and other factors). Additionally, since spider monkeys live in fission-fusion social systems (meaning that, like us, they live in large communities but break up into smaller, variable subgroups throughout the day), we must note whenever monkeys join or leave the group. Finally, we record any social behaviors that occur, from affiliative embraces to threats—which usually involve males displaying their might by breaking branches above our heads.

To me, what is so exciting about fieldwork is how, using such simple methods as these, you can glean so much information about the inner-workings of animal communities. From the data I take home at the end of the summer, I will specifically be focusing on how the monkeys’ behavior changes in different habitat types. We can already tell that the monkeys prefer areas with large, fruiting trees that provide them with the food and shelter they need; additionally, they need to be located near one of the aguadas, or lakes, that serve as the only sources of water in the reserve. Unfortunately, ideal habitats like these are few and far between in Calakmul and, while the forest has been relatively well-protected for so long, the spider monkeys are facing an uncertain future. The president of Mexico recently proposed to widen the road running through the reserve to encourage more tourism, but this could cut the monkeys off from important parts of their home range, placing this population in extreme danger. Therefore, as part of my thesis, I also hope to examine the potential impact of the road-widening project. Hopefully, the government can be convinced that endangering wildlife in an attempt to boost tourism is counterproductive, as these animals are a large part of what makes this forest so special.


Mexico - Caitlin Andrews 3


During my last week in Mexico, I have had a lot of time to reflect upon my experience and the path I took to get here. I consider myself incredibly lucky to have been able to experience what I could have only dreamed about as a seven year old, as I know that so many people do not get that chance. Even more so, I am grateful to the OpWall staff for so generously providing me with the support and expertise that I needed. As I head back home next week, I’m sad to be leaving Mexico, but I’m excited to dive into my data analysis and thesis write-up, and I know that I will find my way back to Mexico someday soon.


Mexico - Caitlin Andrews

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