We found black and white colobus, but that was it. After a while, since we kept seeing four of them, and only four, we decided that maybe we were being followed by them, but could not be certain of that. The students at the chimp house told us some of the studies they are working on and the ways in which they go about it. One undergrad is working with Wrangham to try to see why chimps kill and eat red colobus almost exclusively. Their hypothesis is that the way this colobus jumps is the key.
Most monkeys when chased by the chimps scatter randomly, and simultaneously.
The red colobus if they are in the same tree, wait for the first one on the branch to take off, then the next goes, and so on, so maybe they are easier to catch. I asked if they could explore a nutritional basis for the selection, but this would be difficult to measure I suppose. But there may be other reasons then they are easy to catch. Maybe they taste better. These guys go out each day with video cameras to record the way in which each of the different monkey species jumps from tree to tree.