Fur Rubbing in Callicebus: A Personal Account

It was a normal day in the field at Yvaga Guazu-well, mostly. It had rained the day before, so the mosquitoes were a little worse than normal. However, after visiting Jardin Botanico, I was not in a position to complain about mosquito densities. I was following G4 for the day which I had been doing for about a month and a half at that point, so I was finally in the swing of things (and by that, I mean I could finally locate them, identify individuals and record their behavior without losing them or falling on my face!). We were crossing the road from their main patch of forest over into the mango forest (a favorite snacking point at this time since the mangoes were starting to run out) when I noticed something I hadn’t seen before. Yuvinka had stopped on a plant, bitten off the end of a leaf, and started rubbing it on her chest and arms. Now, thanks to a class I had taken a few months prior to leaving for Bolivia, I was well versed in the behaviors of capuchin monkey-one of which sounded similar to what I was seeing here! I remembered references to them using plants and insects to repel mosquitoes. The behavior also serves a social function in capuchin monkeys, leading to frenzied rubbing events or orgies.  As I watched this behavior, I knew that I was witnessing fur rubbing!

Fur rubbing entails rubbing an object (plant, arthropods, scented materials) on the body. It can serve many functions including repelling insects and other pests, providing treatment for wounds and infections, increasing sexual attractiveness, signaling status, masking their scent and deterring predators. It has been seen in capuchins, owl monkeys, spider monkeys and lemurs, but had not been reported in titi monkeys Given that this was the rainy season and no one was wounded or mating (and the mosquitoes were heaviest), it seems that Yuvi was using the plant as a natural insecticide.

Not thinking of this event as anything that major (other than a cool behavior that I hadn’t seen before), my main concern was on how to record the behavior on my data sheet. It wasn’t eating, or resting really. She wasn’t interacting with any other monkeys. I was stumped, so I made a note of the time, location, monkey involved and continued to follow them for the day. Later that evening, I sent an e-mail to Kim asking where she would like me to record it or if she wanted me to make a new category. Kim, being much wiser in the ways of the titi, instantly recognized this behavior as something that no one had recorded from this species before! While we knew titis were clever, we had no idea up to this point that they could use plants as insecticides. With that realization, the hunt to figure out what was really going on began.

Over the course of the next month and a half, we learned a decent amount. I not only saw Yuvinka fur rub again, but I saw Casanova, Yuvinka’s mate, and Samba, her oldest offspring, join her in doing it! I was later able to video record Casanova using an entire branch of leaves and rubbing his chest with it  (see below). Having observed the behavior on several occasions, it was necessary to then identify the type of plant they were using. For this, we obtained the assistance of Juan Carlos Catari, a Bolivian biologist, who identified the species as Piper tuberculatum. Not only was this a closely related species to the plants used by capuchins, but chemical analysis suggests that is plant has insecticidal and anti-fungal properties!

This experience helps to bring to life many of the amazing life lessons you can learn being a field assistant for this project. First, titis will always surprise you. They do things you never expect, display intelligence beyond what many of us thought capable of their species, and are also very endearing. Second, these projects only work because you are part of a great team and support network. Without the help of Kim, Yuvinka, Vicente, and others in the house, this action would have just been a little side-note in my field journal and not turned into the adventure of discovery that really made my experience with G4. Finally, sometimes it pays to take a step back and take it all in. When running through the forest dodging roots and branches, we can often lose sight of the big picture. Take time to reflect on what you are doing, the opportunity you have, and the great support you have while there. Reflect on WHY you are there, what this information can do to further both our knowledge on these amazing monkeys but also on the impact that our species has on all of nature. At the end of the day, THAT is why many of you will come to the project and THAT is what you will take with you when you return home!