Day in the Life Part 2

Mikumi, the alpha male of Celeste’s, is sitting on a log near us, munching on a grasshopper. He has a thuggish face and a tendency to whack innocent bystanders when under stress, but his ability to maintain control of his group despite his fairly small size has earned him some admirers.  Right now he seems relaxed, diverting attention from his grasshopper only occasionally to scan the group for signs of trouble.  As we watch him, Celeste, the alpha female, runs up and slings her arm around his shoulders, baring her teeth at us in a threat face.  Mikumi swallows the last of the grasshopper and joins in, glowering and bouncing slightly on his haunches.  “Group scan of Celeste: she is in social aggression in contact with Mikumi,” Susan narrates, smiling.  Celeste is now one of the oldest monkeys in our study population—she is almost certainly in her thirties.  Like many of the older females, she has dark, bushy brows.  Males, by contrast, go bald as they get older, just like humans.  Capuchins are lucky to make it to 35 in the wild, but can live to 55 in captivity.

Celeste and Mikumi, power couple. Photo: K. Perry.

“Let’s see, who’s left?” asks Jamie, flipping through the census sheet for the monkeys we haven’t seen yet today.  “Where’s Erebus?  He ought to be easy to spot now.”  You can tell Erebus from the other three juveniles his age by his broad, innocent looking face; and, as of yesterday, the giant rip in his lower lip, probably the relic of a fight with one of the adult females.  Eventually we find him hanging on the edge of the group, cuddled close to Quincy, his partner in exile.  We spend ten minutes monitoring them as they take turns grooming each other, then rejoin the rest of the group.

Quincy and Erebus, fellow outcasts. Photo: K. Perry.

There is considerable commotion in the center of the group: Xananathose, one of the younger juveniles, has caught a mouse, and Harry and Nymphadora, two of his younger cousins, have crowded around to inspect it.  They peer over his shoulder, baby eyes wide with curiosity, as he munches on his prize.  Capuchins learn what is good to eat and what is not by observing their mothers, fathers, and older siblings; food interest is also useful because it may win a baby monkey some extra food. After watching Xananathose in vain for a while, Nymphadora gives up and bounds over to his mother, Kalypso, who is resting nearby (click the link to see how we come up with these monkey names). 

Xananathose devours his mouse as Harry and Nymphadora look on. Photo: K. Perry.

Kalypso is the sweetest of the group’s adult females.  She is nearly indistinguishable from her sister Voldemort: both have the same pretty face and moderately fluffy brows.  There is something about the slant of Voldemort’s eyes, however, that makes her gaze just slightly more sinister.  Kalypso begins quietly grooming her son, ridding his fur of all the sticks, dust, bugs and parasites that have accumulated in a few hours’ rough-and-tumble play.  She inspects his hand and tail while he watches, making soft social peeps.

Nymphadora being groomed by his mother Kalypso. Photo: K. Perry.

As my mom narrates Kalypso’s grooming and I snap photos, we notice that we are being watched.  Turning, we meet the inquisitive and fearless gaze of Buddha, one of the group’s two female juveniles.  Buddha is a very pretty monkey, with almond-shaped eyes and a pattern of ridges on her forehead that make her look like she’s wearing a crown.  Yet she’s no princess—she’s ready to join her siblings in even the most rough-and-tumble play bouts.

Buddha observes the observers. Photo: K. Perry.

As we watch her, she dashes over to her playmate Quaffle, the only other juvenile female in Celeste’s.  The two play wrestle for a while, then calm down and begin performing one of the most interesting behaviors Susan has observed in her years studying the monkeys.  Both Buddha and Quaffle go very still, and then Quaffle pushes her finger deep into Buddha’s nostril.  Buddha grabs Quaffle’s hand and the two of them sit together, eyes closed, for several minutes, their bodies perfectly still.  It is as if they are meditating.  Capuchins have several rituals like this, which spread between members of the same group but are not present in every group Susan studies.  This one she calls “hand sniffing”; the more extreme version, in which one monkey sticks their finger in another’s eye socket, is called “eyeball poking.”  We don’t know what these rituals are for, but they may be a form of bond testing.  By doing something risky with another monkey (like allowing them to stick their dirty finger in your eye), you are showing that you trust them.  If both monkeys are sure that the quality of their friendship is secure, they may be more willing to help each other in fights against other monkeys.

Gambit and Quaffle playing the hand-in-mouth game, a ritual similar to handsniffing. Photo: K. Perry.

When Buddha finally breaks out of her trance and scampers off, Quaffle is joined by the group’s other hand sniffer, adult female Gambit, and her baby Karl.  Gambit is the most edgy of the adult females, meaning that she spends a lot of time hiding on the edge of the group, rather than participating in the politics of its turbulent center.  She is also the youngest adult, and her face and fur are still very clean and white. 

As Gambit and Quaffle begin hand sniffing again, Karl crawls clumsily off his mother’s back and does one of the cutest capuchin baby gestures: he tilts his head back and sticks his tongue out as far as it will go, as though tasting the wind.  Researchers aren’t sure what this behavior means.  It may be a way of detecting important chemicals in the air.  Whatever its true significance, it certainly charms the moneros.

Karl being...Karl. Photo: K. Perry.

We watch this peaceful scene for a while, taking photos and collecting data, but the quiet is not destined to last for long.  Soon, adult female Siberia bounds into view with her baby Dersu on her back and begins screaming at Gambit.  Siberia is easy to recognize because of the small chunk missing from the middle of her bottom lip (probably a relic of one of her many fights).  She head flags to Quaffle, who joins her in threatening Gambit. 

Siberia, recognizable by the split lip she won in one of her many fights, and her adorable baby Dersu. Photo: K. Perry.

“Poor Gambit,” sighs Susan as she takes out her tablet again.  “Well, that’s a complete census.”

Census sheets and focal follows are the two main ways that Susan collects data about the monkeys’ lives.  The census lets us know which monkeys are in a group on a given day, and whether they are pregnant or injured.  Census data can be used to map the makeup of a group over time, determine approximate birth and death dates, and let us study things like male migration patterns.  Focal follows are more detailed.  The moneros pick one monkey and follow it for ten minutes (or, sometimes, an entire day), recording every food it eats and every interaction it has with other monkeys.  Every two and half minutes, at the point sample, researchers also record what the monkey is doing (even if it is just sleeping) and which other monkeys it is close to.  This data can be used to map out monkey social networks.  For example, if a monkey spends a lot of time in proximity to or grooming some other monkey, we can assume that they are good friends, and we can then see whether friends are likely to support each other in fights against other monkeys.

After their breakfast of mora fruits, the monkeys dash off again, heading parallel to the pasture line in the direction of one of our trails, P1.  Capuchins, unlike howlers, Lomas’ other monkey species, spend almost their whole day on the go.  They may nap briefly by the river in the hottest part of the day, but are never still for more than a couple of hours.  Before we follow after them, I stop to retag the most popular mora tree, which we also use for phenology data.  Since 2012, we have been monitoring 600 individual trees in the forest, keeping track of when they produce leaves, flowers and fruit.  This data helps us know what foods are available to the monkeys at different times of year, and how this availability is affected by global climate change.  My mom points me to the tree with her GPS device, and I tie a new strip of biodegradable bright orange flagging tape around its trunk.  Each of the phenology trees is also marked with aluminum tags, but these are harder to see from a distance.  I label the flagging tape with the tree’s code, MO04, in Sharpie, and then rush to catch up with the others.