Thursday, January 15, 2015

Baboons in branches: a networked approach to how monkeys decide to turn down for the night

Having a home base is important for many animals. These places offer both shelter and predictability in the otherwise chaotic day-to-day happenings of an animal’s life. For many primate species, home is a stand of several trees centrally located within their home range. Although most primate species live exclusively in trees, baboons spend nearly their entire day foraging on the ground and only return to the trees in the evening to rest. As part of the Mpala Field Computational Ecology course, we are trying to understand how individual baboons make decisions about where to go and where to rest when they ascend their sleeping trees in the evening. This project includes computer scientists and biologists from several institutions:

Ph.D. Students
Ivan Brugere (Computer Scientist, University of Illinois- Chicago)
Vena Li (Computer Scientist, University of Illinois- Chicago)
Ari Strandburg-Peshkin (Biologist, Princeton University)

Damien Farine (Biologist, UC-Davis, Oxford, and Smithsonian Institute)
David Pappano (Biologist, Princeton University)

We are focusing on a troop of olive baboons that rest near River Camp here at Mpala. Olive baboons (Papio anubis) are among the most common of these semi-terrestrial Old World monkeys living in east Africa. Their face and muzzle resemble the jackal-headed deity, Anubis, hence their scientific namesake. Olive baboons are female philopatric, meaning females remain in the same troop their entire life while males disperse at adulthood to join neighboring groups. A troop of olive baboons can range in size from 20-100, but tend to average around 50 individuals. Baboons are among the most successful groups of primates and can be found in a range of habitats throughout eastern and southern Africa from dry brush land to dense rainforest.

photo credit D. Farine

Every evening we head to River Camp within the Mpala Research Station and set up cameras to monitor a the baboon troop as their ascend their sleeping trees. To determine how individual baboons make decisions about where to go within their sleeping trees, we are modeling both the physical tree and the ascension paths the baboons take as networks. We are then using flow prediction over the network to understand how the state of the tree determines the baboon’s decision. Through this method we hope to uncover patterns that would not be directly observable to scientists on foot using more traditional focal-animal based sampling methods.

photo credit D. Pappano, network by I. Brugere

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