At the end of each day, free-living chimpanzees build elaborate nests and go to sleep for the night. These night nests, typically built high up in the crown of a tree, are thought to serve a number of functions including thermoregulation, protection from predators and parasites, and shelter from the elements. According to one researcher who spent time sleeping both on the ground and in chimpanzee nests, they may also simply provide a more comfortable night’s rest. Chimpanzees spend considerable time selecting the proper trees and branches on which to build their nests and then weaving smaller branches and leaves together to form a mattress or basket. This investment of time and energy makes sense; after all, once they are asleep, it is only the quality of their nest keeping them from falling to the ground below.
Day nests, by contrast, are hastily constructed and typically far less structurally complex. They are also more likely to be made on or near the ground. Day nests are simply a place to relax for a moment before the group moves on to another spot.
The chimps at CSNW tend to follow a similar pattern when it comes to the elevation of their nests. Jamie and Foxie in particular regularly make their day nests on the floor of the playroom or front rooms but will make their night nests almost exclusively on elevated benches or catwalks (while Foxie doesn’t build elaborate nests like the others, she does engage in rudimentary nesting behavior). The biggest difference between the nests of the Cle Elum Seven and those of their wild counterparts is that the Seven’s day and night nests are equally complex. Perhaps this can be explained by the fact the the Cle Elum Seven don’t travel very far during the day, and thus they are free to spend as much time in their days nests as they’d like or even return to them throughout the day if they so choose.
In fact, it’s possible that Jamie’s day nests are even more complex than her night nests. This afternoon I watched her make a nest on the playroom floor. With her new favorite boots tucked into her “pelvic pocket,” she twirled fleece blankets in circles around her for several minutes, pushing and pulling each one to form the perfect shape. Then she carefully wove the ends of those blankets through nearby caging, as if to anchor the otherwise unstable nest to something sturdy. She pulled two of her new books close by, one on tractors and another on the chimpanzee children of Gombe, so that she could flip through them as she drifted off to sleep. To top things off, she pulled the last blanket over herself. With each step of this elaborate process she let out a low moan – a sign of contentment.
Thank you for the post. It is edifying to see Jamie so seemingly content with her
nest and some good books with which to read.
And given the arboreal nature of chimpanzees, I have often wondered why there aren’t any trees in the midst of Young’s Hill? Is their absence due to the anticipation that the chimps would strip the bark and thus kill the tree, which in turn could topple over and injure someone?
Hi Tobin – It’s because of the difficulty in getting new trees established in an area that the chimpanzees have access to; that and the time it takes for trees to mature to the point where they could be climbed. The chimps do like to strip bark and branches from young trees (especially Jody) so it makes establishing a new tree very difficult unless you plant hundreds at a time. And to start a new section of woods from scratch would take decades.
When we built Young’s Hill, the only space available to us was a horse pasture. We decided that the most expedient way to fill it with vegetation other than grass was to plant bamboo. That has worked out well for shade and forage, and the chimps enjoy the structures we build for climbing. Now that we own more land, it may be possible for us to extend Young’s Hill into an existing stand of pine trees. But obviously we have some other, more pressing priorities at this time.
From what we’ve seen at the two other sanctuaries that have some enclosed wooded areas, the younger chimps who grow up in that environment use the trees for climbing but the older chimps that grew up in labs or entertainment prefer the ground or climbing structures. My hope for one day enclosing some of those pine trees is not that the chimps would climb them regularly (even less that they would build nests in the trees) but that they would provide better shade on hot summer days.
Wonderful and descriptive post and thank you so much for it!! Their lives would be so different in the wild, but they have the very best situation they could dream of in captivity being with such caring loving caregivers who think constantly of making their lives better. Love and hugs to you all…
Oh J.B., I am so moved by this post. I remember seeing a documentary on Orangutans where the lead observer climbed into an Orangutans nest hight in the tree top. His amazement was quickly felt. The nest was so intricate and beautiful. I am fascinated that Jamie chooses to tie and secure her blanket nests even though she is bound to the ground. I find this particular fact very interesting. Do you know of other captive chimpanzees who do this or something similar to this? And I have always assumed that all the chimps at CSNW build their night time nests in the catwalks, or the elevated portion of their home, is this correct? Does it vary?
There is no doubt that they are all fascinating, as are their habits and choices. They do not live in the wild, but I believe they still hold the wild within themselves. I believe Jamie is wild and yet I believe Jamie is very human. My feelings for her are deeply bitter sweet. I wish she had been given a natural life, I somehow feel she would have been a brilliant female leader in her community.
Hi Kathleen – I can’t think of another chimpanzee that ties his or her nest to the caging but I would bet that they are out there. I agree it is fascinating to see that particular instinctual element – not just designing for comfort but for security as well – play out in a captive setting. The CSNW chimps do build their night nests off of the ground but not always in the upper portion of the playroom or greenhouse. In fact, Foxie, Jody, and Burrito are more often found on the benches in the front rooms, which are only about seven feet off the ground. But unlike the day nests, the night nests are almost always off the ground…with one exception: Sometimes Burrito goes to bed on the floor in the front rooms, but only when Jody has her swelling and he wants to park himself underneath her to enjoy the view 🙂
Thank you J.B. for the reply. I never focused my thoughts on the significance of the elevation of their nests, nor did realize that they build their day nests in different location/elevations than their night nests. I become bedazzled by the beauty of their nests (or the total lack of nests) and the materials they use that I never stopped to consider the where and why of their nest building.
I appreciate it when you share your knowledge on these factual tidbits. I enjoy reading books on chimpanzees, their behavior/politics and books written on the sanctuaries that home them. But The Seven are my personal friends so having a better understanding of their lives (past and present) and their behavior means so much to me. Oh how I wish you and the staff could be followed about by a writer so you could produce a book on The Cle Elum Seven. To read your wisdom, experience, observations, and love for this gang would be a dream come true for me. I’m sure you could pull this off in your spare time, right?! Ha, ha, ha!
Loved the photo of Jamie and her books. Reading in Bed. Who doesn’t do that? Thank you J.B. for this very informative and interesting insight into their night rituals. Great blog.