Field Notes: Life on Monkey Island

I’m finally back after a summer field season studying monkeys in Japan!


IMG_2989My research was conducted on Koshima Island, the birthplace of Japanese Primatology and home to a population of almost 100 Japanese macaques. You may have heard of them from the classic cultural transmission studies from the site – feeding behaviors such as potato washing were observed to be transmitted through a group and over generations.

However, my research was investigating the effects of parasites on behavior, specifically looking at how treatment of intestinal parasites influences the patterns in which monkeys move. Our hypothesis is that by treating parasites, we would be lifting an energetic constraint and monkeys would behavior in more complex patterns, measured by using fractal analysis. At the beginning of the project a subset of monkeys were given peanuts with peanut-butter mixed with crushed doses of antihelminth medication.  I also spent the first week getting to learn all the individual monkeys.  Being able to identify individual animals is integral to this type of research.

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To collect this data I would follow individual monkeys around and record sequences of their activity and behaviors patterns. It sounds simple; the data are simply sequences of activity. However, following monkeys in their natural habitat is all but simple!

Koshima island is about 30 hectares, and consists mostly of steep forest, some rocky shorelines, and a small beach. There are a few “trails” on the island that I could use when I was traveling back to camp at the end of the day, but when following monkeys, you have to take the routes they take, which more times than not are not so easy for humans.

Most mornings the monkeys would come to the beach, which was a good place to find them. Some days they would travel to rocky shores and feed on shellfish. Other days they would spend most of their time in the forest, foraging in trees. They seemed to have some routes they would often take, though it was hard to predict which they would use so you’d have to follow them all day long.

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Oh, and I almost forgot to mention, I also collected fecal samples from my study animals when I saw one, well, get produced. This way we can validate that the parasite treatment did indeed work by measuring parasite load in their feces.

The island is only 300 meters off the mainland and is accessed by small fishing boats. When the weather is calm this is no problem, but this project was conducted at the beginning of typhoon season. When typhoons were nearby the waves got rough, limiting access to the island even if it is nice and sunny out. This meant that I could easily get stuck on or off the island, both of which happened during the course of the study. We had six nearby typhoons!

Life off the island was at a nearby field station that had full amenities (water, electricity, beds, air conditioning) and was near a gorgeous stretch of beach. Life on the island consisted of an old hut and a tent – true off-the-grid living. Because of the typhoons my data collection was severely delayed, so I collected all my data in an intense stretch of time, no days off, mostly sleeping on the island.

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Despite the intensity of the terrain and data collection schedule, I had an amazing time! The island was beautiful, the monkeys were awesome, and I absolutely loved life in Japan. I have hopes for another field season on Koshima, though maybe not during typhoon season next time!

A more detailed account of my fiend experiences can be found at my field blog.

This research was supported by the National Science Foundation’s EAPSI program and Japanese Society for the Promotion of Science’s Summer Program. I collaborated with Dr. Andrew MacIntosh, a researcher at Kyoto University’s Primate Research Institute.

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