I’m sometimes asked “what’s it like to follow chimpanzees through the forest?”, and the completely unsatisfying answer is that it depends entirely on which chimp, or group of chimps, I’m following. Tracking a big group (and, with close to 200 chimpanzees in the Ngogo community, groups can be REALLY big) full of adult males is a completely different experience than following, say, a mother and her young infant or juvenile. Big groups of adult males do what big groups of adult males of most species will do – they display for females by trying to beat each other up, they run all over the place making lots of noise along the way, they may take a nap or two at some point, then resume beating each other up. Spending the day in the forest with a mother and her young offspring, however, is often nothing like this testosterone-driven frenzy at all.
For example, the other day I went out to collect some fruits from a large fig tree that the chimps like to pig out on (stop me if I’m using too much technical jargon). When I got to the tree, I unfortunately didn’t find too many figs to collect, but I did happen upon a very old adult female chimpanzee named Marlene, plus two of her kids (Hayden, who is a young adolescent male who still hangs around with mom quite a bit, and a juvenile female whose name escapes me). Side note about naming conventions for the chimpanzees at Ngogo: I should have mentioned this in an earlier post. My former PhD advisor, David Watts, who co-directs the Ngogo Chimpanzee Project, is a jazz nut, so from the beginning most of the male chimpanzees (who were “habituated”, or became accustomed to and accepted, the presence of humans earlier than most of the females) in the study community were given names of jazz musicians – Miles, Monk, Coltraine, Ellington, Brubeck, Mingus, Dexter, etc. There are some exceptions, most of which are classical composers’ names (my all-time favorite chimp, Stravinsky, who sadly went up to chimp heaven a few years ago, for example). The same jazz-themed naming convention was started with the females (e.g., Fitzgerald, Lady Day, Ma Rainey), but David started running short on female jazz musician names. He then turned to another of his interests, opera, and started naming female chimps after opera singers (e.g., Fleming), but this also proved to be a dead end. So, “new” females (in the process of habituating a chimpanzee community, it can take many years to find and habituate all of the members of the community, particularly the females) were given names of famous actresses, and that convention has stuck – Jolie, Sigourney, Meryl, Sarandon, Bacall, Kidman, Halle (Berry), etc.
Which brings me back to Marlene, named for the actress Marlene Dietrich. She’s been around for a long time and is one of the most “successful” mothers in the Ngogo community (with “success” defined in terms of surviving offspring). Unlike the boisterous displays and calls that accompany a large group of adult males, and perhaps also an unfortunate estrus female who happens to be the object of the males’ affections that day, mothers and their dependent offspring often travel in very small parties (or alone in their little family group) and barely make a peep. Such was the case with Marlene and her kids. When I first heard them rustling through a grove of Uvariopsis trees (mmmm…. sugar), I just assumed, without looking up into the canopy, that it must be a small group of monkeys, maybe mangabeys or redtails, because they were treading so quietly and softly through the trees. But then I glanced up into the tree to see a little juvenile female chimp staring me down. She stared at me for a good 20 minutes – I stared at her for about 5 before I got tired of the staring contest. Then I heard a crashing sound coming from the Uvariopsis tree next to the one the little juvenile was in, and suddenly, out popped the not-so-photogenic mug of Marlene. They’d been there the whole time, quietly going about their business of getting hopped up on Uvariopsis sugar that I’d almost walked right past them.
It’s often suggested that the reason females, and in particular those with dependent offspring, travel in relatively small groups has to do with feeding competition: the larger the group, the more mouths there are to feed, and females who must devote energy to nourish a growing fetus or to nurse a young infant simply can’t afford to spend time in large parties, in which their share of the food in a given feeding patch will be relatively lower than if they were to forage in smaller parties or alone. Whatever the reason, mothers and their kids will often avoid the big groups, where most of the “action” is, and will also generally remain quiet, perhaps to keep their feeding patch from being seized upon by others who may be in the area. All this makes for a very different chimpanzee-viewing experience. In previous posts I’ve discussed following big groups of males as they charged around, displayed loudly, ran through thick vegetation, caught and killed red colobus monkeys, etc. By contrast, this day spent with Marlene and her little ones was relatively peaceful, almost calming. Females with young kids often don’t like coming down to the ground when a researcher is around, so Marlene was content to spend most of the day traveling through the continuous canopy of the Uvariopsis grove, with her little juvenile in tow. The two played for a while, Marlene tickling the juvenile and vice versa (and this really is tickling as we know it, and is truly “play”, as we know it… if you’ve ever seen it you know it can’t be described in any other way). At one point, Marlene even played a game in which she spit some big Uvariopsis seeds at her little juvenile. The kid tried spitting back, but she obviously didn’t have the chops for it quite yet. They continued on like this for hours, eating, playing, and resting in makeshift “day nests” (chimps make nests out of branches in which they sleep each night, but occasionally will make a nest in the middle of the day if they really need a serious snooze). The little kid continued to try goading me into a staring contest. Hayden, Marlene’s adolescent male, had no problems with me and eventually came down to the ground, but to my surprise he didn’t move off to join the big boys. Instead, he stayed with his mom and sister, content to nap on the ground while they fed and played up in the trees. It was nice to spend the day with this happy little family, an old mother, her young daughter, and older son (who’s still obviously a momma’s boy). Not exactly the same experience as tearing through thick vegetation at full speed while big adult males yell and scream and beat each other up, while in search for monkey meat. So, what’s it like following chimpanzees through the forest? Well, it depends….