Much Belated Post

Sorry to all for this much belated post. This should give you some updates about my research, for which I am looking into the gestural communications of saki monkeys at the National Zoo in Washington. There were some questions on an earlier posts that I’ll start by answering, and then move on to where my research is at this point.

To begin with, there has been very little research done on saki monkeys at all. They’re extremely quiet (I don’t think I’ve heard them vocalize at all!) and shy and haven’t been studied much in the wild. Though they can be seen in a variety of zoos, for instance in pairs at the Bronx Zoo and the Prospect Park Zoo in Arkansas, but I haven’t found prior work on captive sakis either.
The other questions related to the co-regulation aspect of my project, which I’m sad to say that I’ve had to reassess. After watching close to 30 hours of film (half of my intended total), I have found no gestural sequence or communication that reaches anywhere close to a comfortable definition of coregulation. There are some interesting gestures that I’ll outline below, and I am getting good data, but coregulation just isn’t as common as I hypothesized and thought.

I’ve found five separate gestures as of now, but there are some others that could eventually be categorized as such. To meet the definition of a gesture, the action must occur at least twice at different times, and be intended. Intention, of course, is a tricky beast to determine, but the benchmark is waiting/looking for a response and changing behavior or repeating the gesture if response is not forthcoming. One interesting thing to note is that all the gestures I’ve observed are tactile (touch), which makes sense given the sakis’ quiet nature , but I haven’t yet developed any clear hypothesis as to why this may be. Literature on other primate gestures has made some connection between the arborality of a species and the types of gestures they make, and I’ll have to look into that further.

The five gestures:
Hold Hands – This is by far the most common gesture I’ve seen. One saki will approach and look for the hand of his or her partner, then reach out and try to hold it. Sometimes the partner will withdraw his or her hand and move away but more often will allow his or her hand to be held. This gesture usually precedes other gestures that will occur later, but sometimes the sakis will just sit closely and hold each other’s hands.

Muzzle sniffing – I’ve observed this in only one of the two pairs. In a situation like that described above, when the sakis are sitting close to each other, an individual will move to sit facing the other, then reach up and reposition the other’s face so that they are directly in front of one another. The sakis then open their mouths and press their faces together, presumably to sniff each others muzzles. In all honesty, it looks like they’re kissing, and neither I, nor the keepers have a good explanation as to what they’re actually doing.

Move – A very simple gesture in which a saki will tap the other to move into a certain a direction or off of a desired location.
Stop – To end a session of grooming, the one being groomed will occasionally reach up and push down on the arms of the other, signaling for the grooming to stop.
Groom my neck – This is the most complex gesture I’ve seen. One of the sakis will lie down in front of the other, exposing the back of its neck, and begin tugging on the hair of the partner to signal that it wants its neck groomed.
Unfortunately due to the size limits on files I can’t upload any film, but here’s a link to other saki monkeys kept at the Prospect Park Zoo.


  1. pbterenzioiii says:

    This is some fascinating stuff- I’ve always found the study of primates to be quite interesting. I do have a question though. Do you think their lack of vocalization has anything to do with them being in captivity, or are they normally extremely quiet, even in the wild?