July 1st, 2016 by J.B.

Upon seeing chimpanzees for the first time, most people are struck by the extensive physical similarities between our two species, but there’s one notable difference that also catches everyone’s attention…

What’s wrong with their butts?


Chimpanzees, along with many other primates such as baboons and macaques, advertise their fertility by means of sexual swellings. As they approach ovulation, ovarian hormones induce the skin around their genitals to swell and take on a pink hue, an effect known as tumescence. Following ovulation, other hormones cause the swelling to subside and the roughly 35-day menstrual cycle begins again.

Why does this happen? Believe it or not, no one really knows for sure. It could be that it promotes paternal care by increasing the certainly that a particular male was the father of a female’s offspring. Or it could increase competition between males for mating access, thereby helping females filter for males with greater fitness. Or it could provide more immediate benefits to the females, as the males must work to protect them during their consortships. The list of hypotheses goes on, but none seem to be fully supported by the data on their own. In all likelihood, it is some combination of these factors. Interestingly (to primatologists, anyway), a recent study of free-living bonobos found that while they exhibit sexual swellings, their swellings do not reliably indicate fertility as they do in their chimpanzee cousins. Like humans, it seems that bonobos conceal ovulation. Bonobo societies are structured very differently than chimpanzee societies – they are quite famously female dominated – so it may be that a different evolutionary strategy was required.

One thing is for sure – swellings have a significant effect on male chimpanzees. Male chimpanzees aren’t exactly the more level-headed of the two sexes to begin with, but when tumescent females are present, all bets are off. Those big, pink backsides make the females incredibly attractive to the males and it can ignite a lot of testosterone-fueled behavior. In addition to an overall uptick in group tension and aggression, one result we often see is a behavior called mate guarding.


I remember learning about mate guarding the hard way when volunteering at another sanctuary. I was just getting to know two young adult chimps named Jethro and Rachel and I enjoyed interacting with both of them each time I visited. Then one day, all I did was say hello to Rachel and before I knew it, Jethro had spit a huge mouthful of water directly in my face. The lesson was clear: Rachel was off limits when she had her swelling.

We don’t see mate guarding per se here at CSNW, but that’s not to say that Burrito is unaffected by the swellings of the females in his group. He loves them. He loves them so much that he follows the girls wherever they go when they have their swellings. He loves them so much that he sleeps on the floor below the benches where the girls makes their nests so that he can stare at them all night.


Sadly, Burrito never exhibits any other mating behavior. Many chimps raised in unnatural environments like laboratory nurseries or human homes never develop these skills, despite some rather obvious biological urges. But while his interest in the girls may be limited to looking, he is unrelenting. In the wild, the young, tumescent females – dubbed “pink ladies” by Jane Goodall – are said to like the attention it brings them. My guess is that Burrito’s group mates would gladly send him off on a vacation one week each month if they could.


Among the Cle Elum Seven, only Annie, Jamie, and Jody experience sexual swellings. Foxie and Missy had complete hysterectomies shortly before coming to the sanctuary due to the discovery of uterine tumors during their pre-shipment physicals. As a result, they no longer experience the same estrogen and progesterone cycles that govern these swellings. And while we have no record of Negra undergoing a hysterectomy, she doesn’t cycle either. Menopause isn’t common in chimpanzees, but just as we see in humans, there are other factors that can disrupt or cease menstrual cycles.


There is a lot of natural variation in the size of the females’ swellings, and on top of that, physical trauma to the sex skin can cause it to lose its shape. So some swellings, like Annie’s, are barely noticeable, while others, like Jody’s, are so big they make sitting down difficult. According to Burrito (and much of the scientific literature) it seems that bigger is generally better, but that probably depends on your perspective.







Nothing Much Going On

June 30th, 2016 by Elizabeth

If you follow our blog regularly, you might get the impression that the chimpanzees are always up to something. And they do spend a lot of time playing, eating, grooming, and exploring. But they also enjoy downtime.

Summer mornings

June 29th, 2016 by Katelyn

Our recent heatwave is on the down-slide, but it’s still quite warm and the chimps and humans are each enjoying the summer days in their own way. After breakfast, most of the chimpanzees headed for the still cool grass of Young’s Hill (with the exception of Negra who took a break from her adventures for the day and made a nest at the top of the greenhouse where she could enjoy the morning breeze). Annie chose to take a walk up the hill bipedally to join Foxie and her troll. If you look closely you can spot the troll’s red hair on Foxie’s back.






Missy took her breakfast chow and literally ran out to climb up a structure where she could enjoy it with a view:


Jody was the first to head out onto Young’s Hill this morning and quickly disappeared into the tall grass to forage for wild greens before her buddy, Burrito, could catch up with her. So he opted to sit in the raceway which leads from the greenhouse to the hill and enjoy the morning sun with me, remaining on the lookout for Jody’s return.



After a busy morning on the hill, by late morning things got pretty warm and Jamie sprawled out in a comfy nest to cool off and doze in the summer breeze.





How profoundly grateful we are that the chimpanzees’ days are filled with such serenity, comfort and peace. Thanks to all of you who make the hours, days and seasons of their lives so beautiful.

Three tips for beating the heat- Chimpanzee style.

June 28th, 2016 by Anna

Tip #1: Exercise first thing in the morning (or late at night if you ask Jamie)…

Boss Jamie (front) and her posse explore Young’s Hill first thing this morning :

Tip #2: Nap in the coolest area of your home, keeping your limbs elevated… If done properly you may even require a light blanket…

Jamie relaxes on the floor in the shady playroom :

Tip #3: Make sure you eat lots of refreshing snacks…

Burrito stays cool as a cucumber:

In memory of Bryan

June 28th, 2016 by Katelyn

This day of sanctuary was sponsored by Judy Riner in memory of her husband, Bryan Riner, and she shared this beautiful message about her special gift in his honor:

“Bryan Riner loved and respected chimps. He especially enjoyed following the lives of the Cle Elum Seven, and he would be proud to know that his family honors his memory in this way. He was a loving husband and father, and that love and compassion extended to all species.”

Judy, thank you so very much for this special gift in Bryan’s memory. You and your family have been such good friends to the chimpanzees and we are honored to celebrate Bryan here today. All of us here at the sanctuary will be holding you all in our hearts and minds. We hope that the love you extend to the chimpanzees, enabling them to live their lives full of joy and comfort, is felt all around you as you celebrate Bryan and his wonderful legacy of compassion and respect for all our fellow beings.

Annie and Missy:


Burrito and Jody:

web Burrito Jody groom platform greenhouse GH IMG_3121

Foxie and Negra:

web negra foxie groom cute greenhouse GH IMG_9850

Jamie and Negra:

Negra kiss Jamie


June 27th, 2016 by Elizabeth

Once in awhile we make bubbles for the chimps with a small drop of non-toxic dish soap. They seem to like how the bubbles feel in their mouths.

Today is in memory of Susan

June 27th, 2016 by Katelyn

This day of sanctuary was sponsored by Jennifer and James Douglas to honor the memory of their dear friend, Susan von Beck Turner, and her legacy of care and compassion. Jen and James shared that “Susan touched the lives of many dogs and humans and made them better.”

Susan made a difference in the lives of so many dogs. It was her lifelong passion to rescue them and she saved hundreds, healing their health and spirits and finding them forever homes. When Susan’s own dog, Cardiff, began failing in health and she was unable to find the kind of boarding care she wanted for him, she decided to leave her job and went on to build a well-respected and successful dog boarding facility, Cardiff’s Lodge, here in Washington.

Jen and James, thank you so much for celebrating Susan’s life with such a compassionate and generous gift for the chimpanzees. We are profoundly grateful for all that you do for them and we are honored to celebrate such a special soul today. To you, and Susan’s family and friends, our thoughts are with you all and we hope that your memories of Susan bring you the joy, love and comfort that she provided to so many others.




Playing with a caregiver, Foxie style

June 26th, 2016 by Keri

Foxie gets pretty excited when she sees a new troll or Dora the Explorer doll. Today, thanks to our generous supporters, Foxie had a plethora of troll dolls to choose from. Instead of giving them to her one troll at a time, this morning we thought it would be fun to put them all into one container and wait to see which one(s) she would choose.


Turns out, she grabbed one with bright red hair first (you can just see a little tuft of the red-haired doll’s hair sticking up on the left hand side in the the above photo) but quickly went back for another when Jamie took it away.

Jody showed some interest in the dolls as well.


When I walked out to the Greenhouse a little while later, I saw Foxie and staff caregiver Katelyn playing….

She had chosen a new doll (with yellow hair) to pass back and forth to Katelyn.



What’s in a Nest?

June 25th, 2016 by Diana

An intriguing article is making the rounds about a primatologist named Koichiro Zamma who has developed a bed, called the humankind evolution bed, that is based on how chimpanzees construct their own beds in the forests. Apparently he tried out a chimpanzee-constructed nest  while tracking chimpanzees in the wild and found it to be very comfortable, waking up quite refreshed after his night of nesting.

A prototype of his invention is currently on display at Kyoto University Museum in Japan. Articles say this about the bed: “The mattress features a depression in the centre to replicate the natural dip in a chimp’s treetop bed and has a raised periphery for the head, legs and arms. It is supported by a frame made from woven paper string for maximum breathability, and eight curved legs that are designed to allow the bed to rock almost imperceptibly.”

humankind evolution bed

Megumi Kaji of the Research Association of Sleep and Society takes a nap on the humankind evolution bed. Photograph: Koichiro Zamma


As we’ve written in the past, chimpanzees in captivity make similar constructions for their nests as their free-living counterparts, building up walls of material (blankets, straw, paper, etc), and laying in the middle.

Jody is a master nest-maker:


Missy makes a pretty mean nest too. This was one of my favorite photos from the early days of the sanctuary:

Missy in tire nest

In fact, these two were featured in this tutorial-style blog post about how to nest.

Here are some more photos of nesting from the Cle Elum Seven:

Jamie's paper nest

Missy constructed nest

Missy sleeping in a big nest

Negra nesting


I have to admit that I wonder if perhaps Zamma’s restful night of sleep was due to being particularly exhausted after a day of following chimpanzees around the forest, but I remain intrigued.

What do you think – are chimpanzees on to something that we should be paying attention to? Should we ditch our flat mattresses? Would you want a humankind evolution bed?


Playful mornings

June 24th, 2016 by J.B.

The staff have a lot do to each morning before they are ready to serve the chimps their breakfast. What’s a chimp to do in the meantime?