Tuanan is one of the premier wild orangutan research sites in the world. It is located in a peat swamp forest (one of the most important carbon sinks in the world) and has an incredibly high density of orangutans. Still, the habitat at Tuanan is relatively marginal compared to many other tropical forests and orangutans, in general, have several adaptations to survive in this type of environment. One characteristic is an incredibly long period of juvenile dependency: an orangutan infant at Tuanan will nurse for up to 5 years and stay with its mother for up to 8 years! My graduate research aims to explore how an orangutan mother (orangutans are the largest arboreal mammal in the world) can survive through periods of fruit scarcity while supporting an infant for such a long period. What is her energetic status and how does it vary on a day-to-day or seasonal basis? Are there any activities that help her survive along the way, such as eating particular foods at particular infant developmental stages?
Generally speaking, my research is broken up into several parts. First, there is the behavioral observation of orangutans, where my volunteer, Rumaan, our amazing team of local Indonesian assistants, or I spend an entire day following a mother orangutan, taking special note of what she eats and for how long, how much time she rests, and how much time she spends moving between feeding/resting locations. The behavioral observations are the base information we need to assess how orangutan mothers are doing.
A second part is collecting the urine from the mothers we follow. Urine is a gold mine when it comes to information about the body. As you can probably guess, my focus is on the energetic information found in urinary ketones (which show fat catabolism), C-peptide of insulin (which show energetic status), cortisol (which show energetic stress), and creatinine (which show muscle mass loss). Most of these analyses take place back at Rutgers, though.
The third part, and the most exciting to do in the field, is the sampling of the food items that the orangutans eat. This can include anything from leaves to fruit to bark to insects. Unless we collect samples as the orangutans drop them while they eat, most of the time we have to climb trees to get what we need. The trees can be anywhere from 10 meters to 30 meters high, and for me, the higher the tree the more fun I have. Once we collect the sample, we must take it back to camp for processing, which includes cutting them into tiny pieces and drying it so we can have them analyzed for their nutritional components (protein, fats, carbohydrates, fiber).
I am a problem-solver at heart and drying food samples requires a ton of problem solving (especially ripe fruits because they have so much water in them, up to 99%). There are several competing elements to drying fruit, and temperature is the most important factor involved. To preserve the nutritional information in a sample, you have to maintain a relatively low drying temperature. Unfortunately, low temperatures mean longer drying times and longer drying times mean more exposure to humidity and the potential for mold. In the past, we have used kerosene ovens to dry samples, but the temperature is hard to control and the wicks must be monitored closely. This year, I brought with me a food dehydrator and it has revolutionized the process. The only problem is that for it to run the required amount of time, we need a constant power source (the camp generator is only on for five hours a day). Enters one of my favorite hobbies…building stuff. In order to solve the power supply problem, my friend Rahmatdi, Rumaan, and I built a generator with a 3000W alternator and a 6.5hp small engine. Rumaan and I also built a nice platform for the generator, which is running smoothly as I write.
Field work requires a lot of thinking outside the box. Every week brings with it a new obstacle to overcome and being in such a remote location means one has to understand what they have available and think of the best possible solution. This is my favorite part of field work. My least favorite part: flies and mosquitos, but who can really blame me on that one?