Burrito was a major distraction from Playroom cleaning for us this morning. Every time we saw him he was doing something wildly playful with one of his friends. I frequently abandoned poor Kelsi to do the cleaning by herself so I could grab some footage of the action!
wild
Missy on a Mission
Missy invited me to play chase up the hill this afternoon. When we reached the top, she veered off into the tall grass with a look of determination.
She climbed atop one of the mounds.
And then walked out onto the log bridge.
From there, she scanned the area.
Then she disappeared into the weeds.
When she emerged, it was clear she had found what she was searching for: a yellow goatsbeard flower and a handful of prickly lettuce leaves.
With an equal sense of purpose, she marched through the grass to Jamie’s Tower.
She climbed the ladder and perched on a support.
There, overlooking the river canyon, she munched on her prickly lettuce.
When she was done, she met up with her best friend, Annie, and returned to the chimp house, saving the flower for later.
All you can eat
Chimpanzees seem to have a pretty good sense of time. Even if we haven’t started preparing dinner yet, the chimps at CSNW begin to gather near the window to the kitchen around 4 o’clock. They want to see what’s on the menu and remind us to hurry things along. But every once and a while, it remains ghostly quiet as dinner time nears – no one blowing raspberries at us, banging on the caging, clapping their hands, or stomping their feet. When this happens, it usually means one thing: They’ve started on dinner without us.
Chimps in captivity rely on humans for so much. Those who were wild caught, like Negra and Annie, were torn from their families, deprived of their native cultures, and forced into complete dependence on humans. And in some ways, they were the lucky ones, because those born into captivity never even got to experience a moment of independence in their lives. So when they learn to take back a tiny bit of autonomy, as they do when they choose when and what they’d like to eat, it is cause for celebration. And with two acres and a greenhouse full of bamboo and native plants, the chimps are able to make these choices every day.
Eating plants is good for their health, too. Chimps in the wild eat large quantities of rough fiber in the form of shoots, stems, and leaves. And while I don’t think we know yet exactly what role all of these foods play in their diet, we do know that this type if roughage allows captive chimps to snack all they want without putting them at risk for diet-related illnesses like heart disease and diabetes.
There are currently seven species of bamboo growing on Young’s Hill, and the chimps harvest from them year-round. Surprisingly, the bamboo on the hill seems to be prized most for its leaves, and the chimps tend to leave the fragile (but I would imagine tasty) shoots alone.
A few other species of bamboo that are more sensitive to Cle Elum’s chilly winters do very well in the chimps’ greenhouse enclosure, and send up their tender shoots (Chusquea gigantea shoots seems to be a delicacy) as early as March.
But in May, all of Young’s Hill becomes an all-you-can-eat salad bar. Even Negra will sit outside to snack on fresh dandelion greens.
Missy, always on the move, takes hers to go.
Spring grass is a favorite of nearly all the chimps. Annie collects only the best blades to bring back to the greenhouse.
In mid-summer, some larger plants begin to grow. Most people would consider them weeds, but the chimps think otherwise. Jody likes mullein, which I imagine to be the equivalent of eating bitter craft felt, but Jody must have a more refined palette.
Missy and a few others like prickly lettuce, which we mistook for dandelions for a while until we picked up some of their leftovers – they are just as prickly as the name suggests. Just like in the wild, captive chimpanzees will sometimes eat foods that are physically difficult to ingest. While many of the plants consumed by wild chimps have been shown to have medicinal value, such as the anti-parasitical Aspilia leaves, we don’t know if captive chimps are attempting to self medicate or are just eating adventurously.
The bane of my existence is this wild mustard. It grows so big and tough that it will break your weed eater. But when it grows inside the chimps’ enclosure, it gets taken care of by nature’s weed eater, otherwise known as Jody.
The chimps could never live on these plants alone, even if they do supplement with the occasional live frog like Negra does. But they are important in other ways. Like tonight, when the chimps all disappeared onto the hill just before dinner, you could almost hear them saying:
To heck with the humans, let’s eat!
The wild and the weird
When given the opportunity, chimpanzees who have spent their entire lives in laboratory cages can learn to be chimps again.
They can learn to climb, run, leap, and swing:
They can learn to forage for their own snacks:
And they can learn to patrol and defend their territory :
But it takes patience. When you’ve spent your entire life surrounded by concrete and bars, those things can end up providing a certain kind of comfort. It’s what you know. It’s all you’ve ever known.
Little by little, the chimps at CSNW have embraced new opportunities, confronted some of their fears, and found that there was a little more “wild” in them than they may have realized when they were locked up in that laboratory basement.
This year, these changes seem to be happening at an accelerated pace. Burrito has been joining Jamie on her walks around the hill, and even going it alone at times. A couple of weeks ago, Foxie was seen sitting on the shaky bridge – a huge step for someone who has always been afraid of anything not firmly bolted down.
And this morning, we saw almost the entire troop take a walk up the hill together, far away from the building, just for the fun of it.
But along with patience, you also need understanding. Because these new experiences are adding to who they are, not replacing who they were. Foxie may be exploring new play structures, but she’s relying on Dora more than ever:
And while Jamie may be walking miles each day around the perimeter of Young’s Hill, she is ever more adamant that we dress in cowboy boots to go along with her. Let me give you an example of how particular she has become: Jamie’s favorite boots for the last few months have been a pair of all black women’s cowboy boots. She insists that her caregivers put them on before heading out on a walk. But some of us, ahem, do not fit easily into women’s boots, no matter how hard we try. That doesn’t concern Jamie. For a while, I tried to fake like I had them on, sticking just my toes in and then pulling my jeans down over them to cover my heels sticking out. No dice. As you put them on, she stares intently to ensure that you are wearing them properly. Heels must be all the way down.
There are times when I am reminded how crazy this all is – like when we finish up a walk and I return to the entry gate, only to have to strut my stuff across the driveway in ladies boots as the UPS driver unloads packages at the door. They must really wonder what’s going on here.
It’s crazy, but it’s who they are. You can’t erase their past, or what it’s led them to become. And why would you want to? So while we strive to provide more and more “wild” in their lives, we can never stop embracing the weird.
How long do chimpanzees live?
It’s one of the most commonly asked questions about chimpanzees and for most of the last 15 years I’ve been answering it incorrectly. In my defense, I was not alone. Search the internet for “chimpanzee lifespan” and you will often read that chimpanzees live 40-50 years in the wild and 50-60 years in captivity, or something to this effect. This was the standard line when I first started to learn about chimps, but it now appears to be wildly inaccurate. How could this be?
For such a simple question, the answer for many years was difficult to come by. If, for example, you asked, “How long do fruit flies live?” the answer would be cut and dry. Just follow a bunch of fruit flies from birth to death and record their lifespan, which is measured in days. But for a species like the chimpanzee that has only been studied on a large scale for a handful of generations and whose lifespan is measured in decades, good data was hard to come by. Over the years, however, researchers have collected more and more data on captive and wild chimpanzees and a new picture has emerged, one which has drastically changed my own understanding of chimpanzees.
So…how long do chimpanzees really live?
For chimpanzees in captivity, the best information we have is this: For those who survive to their first birthday, median life expectancy is 31.7 years for males and 38.7 years for females. These figures were provided to us by Lincoln Park Zoo’s ChimpDATA as part of a unique program we participated in to help project future demographic trends in sanctuaries, and are based on 35 years of records from Association of Zoos & Aquariums (AZA) institutions.
A couple of technical points, if you’re interested: First, you’ll notice that this excludes infant mortality. If infant deaths were included, life expectancies would be even lower (closer to 32 years for males and females combined, I believe). The reason why infant deaths are excluded is because infancy remains a particularly high-risk period, even in captivity. If we want to know how long a yet-to-be-born chimpanzee might live, we might include it. But most of the time we are trying to determine the expected lifespan of chimpanzees who are already young adults or adults (typical of chimpanzees coming to sanctuaries), who by definition have already beaten the odds of that early high-risk period. Second, these figures are median ages. The way to interpret this is that for a given figure, half of all chimpanzees in that category will die before that age, and half will die after that age. So you would expect to see many chimpanzees live past the median age – in fact, one chimpanzee in the AZA group lived to 72. However, you would also expect an equal number to die before the median age. Finally, we don’t know how different captive environments and life histories affect life expectancy, so it’s possible that future data from sanctuaries will change our understanding of this unique population.
Life expectancy in wild chimpanzees tends to be the same or lower than in captive chimpanzees. One study found that average life expectancy for chimpanzees across five field study sites was only 15 years. But for those chimpanzees who survived to adulthood, which in this study was defined as 12 years old, their life expectancy was an additional 15 years. Of course, many wild chimpanzees live well beyond 27 years – the oldest wild chimpanzee was estimated to be about 63 years old when she died. Direct comparisons between these types of studies can be difficult because they use different methodologies and analyses, but it gives you a rough idea.
The importance of this issue is not just academic – it has the power to shape the way we think about many different aspects of captive chimpanzee care. As we learned through ChimpDATA, information about life expectancy can help us predict future capacity in sanctuaries, as well as the costs associated with caring for a chimpanzee across his or her lifetime. But just as importantly, it can help give us more realistic expectations about the lives of the chimpanzees that we all care for and support.
