Chimpanzee Sanctuary Northwest

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Surrounded by Liars

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Next time you wander around the woods, take a moment to appreciate the fact that you are surrounded by liars.

The natural world is filled with examples of deception: Opossums that play dead when cornered. Butterflies that mimic a predator’s gaze.  Bugs that look like sticks. Flowers that look like bugs. Bugs that look like flowers. I swear, you can’t trust anyone out there.

Chimpanzees are not above such trickery and, given their social intelligence, may be among the most advanced practitioners of the art, at least when it comes to their behavior. In fact, there’s a considerable amount of evidence for chimpanzees’ abilities to consciously deceive other apes. But lately I’ve been obsessed with another form of deception that is almost certainly not under conscious control but which is nonetheless quite interesting and surprisingly understudied, and that is the female chimpanzee’s ability to falsely advertise her own ovulation.

It’s well known that female chimpanzees in the wild tend to time their emigration from their natal communities with the onset of their first sexual swellings. These swellings, in which the skin around the anogenital region becomes pink and engorged with fluid, are generally thought to be an honest signal of fertility. Peak swelling, or tumescence, tends to coincide with the maximum probability of ovulation, which occurs every 35 days or so. So a swelling is essentially a big billboard that says Mate with Me Now if You Want the Best Chance at Having Offspring. And the boys certainly take notice.

There are a number of theories to explain the benefits of such advertisements to the females’ own reproductive success. But one prominent theory holds that females use these swellings to their advantage in another way entirely—for their own protection. By delaying emigration until they are tumescent, the swellings can act as a “social passport” to facilitate their acceptance into the new group. It’s dangerous for chimpanzees to enter different communities—after all, they are largely unrelated to the locals but end up competing for precious resources, including food and mating opportunities. But the males just can’t say no to a young female with a big backside so they will personally welcome the newcomer and protect them from resident females that may feel less generous. How thoughtful of them!

The fact that female chimpanzees time their journeys so as to manipulate the boys in this way, consciously or not, is pretty cool in and of itself. But those of us who care for chimpanzees in captivity have noticed that social dynamics can actually cause changes in tumescence. Specifically, when there’s a sudden influx of unknown males and the risks of conflict increase, which is rare in the wild but happens regularly during social introductions in captivity, females have been seen becoming swollen spontaneously, regardless of where they are in their reproductive cycles. We’ve seen this in CSNW’s own females when new groups are formed during intros—the girls begin the day with flat butts and go to bed with big, bulbous backsides. Why would this happen? We don’t know for sure, and I can’t believe that no one has studied it in detail (ahem…incoming graduate students looking for a thesis topic!). But it’s not difficult to imagine these swellings serving a role similar to the social passport and building off the same two facts of chimpanzee life: First, males are easily manipulated. And second, at times of great peril, it pays to have a big butt—even if you have to lie.

Cy’s Ultrasound

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Cy’s last exam showed some testicular edema, which is not uncommon in chimpanzees like Cy with congestive heart disease. His veterinary team and caregivers began training him so that we could gather diagnostic images using ultrasound and share them with specialists. This will help us monitor the amount of fluid around his testicles more frequently than we could with a full exam under anesthesia and thus keep better track of his overall health.

Kudos to our vet and PRT teams for another success in cooperative medical care!

Two Awkward Guys

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As Diana mentioned, we swapped Gordo and Terry in the reintro group yesterday to try to get a better idea of what might trigger Willy B’s antisocial behavior. The reunion between Terry and Honey B was easy – after a brief, half-hearted display, Terry approached the mesh and the two began to play, at which point we simply opened the door between them.

We knew that Gordo would be nervous reentering a group with Willy B so we tried to ensure that Cy, the group’s alpha, would be the first to greet him when the door was opened. We could have introduced Gordo to a subset of the reintro group initially but since they all know each other so well we thought we’d just get right to it.

There are several interesting things to watch here. First, you can see how Cy polices the behavior of his subordinates and protects the vulnerable—you can see his “feets of fury” (thank you, Sabrina) in action in the playroom scene as he tells Willy B to step down. He’s a good guy. Second, you can see how the females attempt to modulate the behaviors of the males through distractions and grooming. Rayne is particularly adept at this and very in tune with the needs of her group, always watching for moments when the boys might need a little help getting along. And finally, you can see clearly how chimpanzees express trust in one another—which is, of course, by putting sensitive body parts in each other’s mouths.

This interaction between Gordo and Willy B may seem at first glance like two best friends rejoicing in being reunited but this is actually what is looks like when chimps don’t trust each other. These lengthy, exaggerated displays of vulnerability (e.g., putting your fingers, backside, or scrotum in between another chimps’ gigantic canine teeth) are more common when there isn’t already a solid basis of trust. It’s also common for males to display erections in these circumstances, which may be another evolved display of vulnerability (chimp penises are usually fully retracted into the body for protection). I imagine some of our own greeting gestures such as shaking hands and bowing aren’t that far removed from these same behaviors, though obviously a bit more PG-rated according to our sensibilities.

It will be interesting to see how Gordo’s presence (and Terry’s absence) in the group changes Willy’s behavior, if at all.

 

How to Handle a Bully

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I thought it would be a good time for another quick update on our reintroduction process (see an initial overview here, and a previous update here).

Actually, there’s not much in the way of news to report. We are still holding steady with Gordo and Honey B in one group and everyone else in the reintro group. The reason for remaining so long in this stage is that while Willy has shown glimmers of improvement, his tendencies are right there at the simmering point, ready to boil over as soon as his enabler (Honey B) rejoins the group. So we’re not rushing anything.

What has Willy been doing? For the most part, it’s his usual combination of obnoxious displays that persist until they result in a fight and the occasional (but now far less common) bullying of poor Terry. At their current frequency and level of severity, they are tolerable. And Willy has actually faced more frequent consequences, which could potentially be a good thing. On two occasions, the group had enough of his behavior and they went after him, with only Willy B’s idol and savior, Cy, defending him. Willy walked away humbled, if only temporarily, with some scratches and bites to keep for a while as souvenirs of his encounters. For most chimpanzees, these would be learning opportunities but Willy is not known to be a quick study.

But back to those glimmers. On one occasion, when Willy was beginning one of his intimidation campaigns towards Terry, Terry ran right to Willy B and hugged him. That put an end to it. Could Terry learn to do that again? And would it continue to stop Willy in his tracks? Submissive behavior has never worked for Terry before so maybe awkward hugs are the key. I know they would work on me.

One of our next steps will be to sub Terry out for Gordo to see if Willy fixates exclusively on intimidating Terry or if, without Terry present, he would exhibit the same behavior towards Gordo. That would tell us something about where to go next.

You’ll notice from these descriptions that problematic group dynamics are rarely the result of one actor alone. There are dozens of chimp bullies out there and their group mates somehow manage to coexist with them (see: Jamie). And there are plenty of insecure chimpanzees in the world, who eventually manage to find their place in a group (see: Annie). For Willy, it’s a lack of status and sense of security combined with bullying tendencies combined with a target that overreacts combined with an overly protective alpha male combined with an enabler that likes to kick butt and ask questions later. So while you could say that Willy B is ultimately responsible, kick out just one of the legs that props this whole pattern up and you might have a different outcome entirely.

Now imagine all the potential solutions that these causes present and you’ll see why it’s such a difficult problem to solve. Perhaps Willy would just be happier in a smaller group. OK, but who would be forced to live with him? And would they be happier in a smaller group or would they suffer the missed friendships and the lack of community that larger groups provide? Maybe Willy just can’t live peacefully with Terry. Or maybe Honey B is just too bad of an influence on Willy. Which one of the three of them gets kicked out of the group and leaves their friends behind?

If the thought of Willy living alone as a possible solution crossed your mind, I understand. I know some readers still hold him responsible for the injuries Burrito received in an earlier intro attempt (the greatest trick Honey B ever played was to convince the world that Willy was responsible…). But as a staunch disbeliever in free will, who will happily annoy anyone within earshot of this opinion, I can only view Willy as a victim himself — of his upbringing, of his brain chemistry, of his circumstances — who deserves break, too. So we’ll keep experimenting with different reintro groupings, new behavioral medications, novel enrichment interventions, and so on, with the hope that we can find something that works for everyone.

On a lighter note, and the reason for this blog title: You have to appreciate Rayne for her ability to put a guy in his place.

Bargaining

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Two things I know about chimps:

1. Whatever it is, they will find a way to break it.

2. If you want something from them, they will give it to you…for a price.

Ellen has been coming up with some really cool food puzzles lately. One, named the hanging holey lid, involves a 5-gallon bucket lid that the chimps have to rotate to reveal food beneath. The chimps discovered that the lids come with thin peel-off strips around their circumference, and they were very entertained by peeling them off and using them to floss their teeth. There’s nothing particularly dangerous about these strips of plastic but they weren’t meant to be given to the chimps so we decided to retrieve them.

Most chimps will trade for juice. But Cy had to raise the stakes…