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Update on Uzumma's pregnancy. What to Expect When You’re Expecting: Gorilla Edition

Posted by Elizabeth Bacher with Stephanie Jacobs

Uzumma, who is pregnant with her first baby due next spring, is doing really well! Photo: Jeremy Dwyer-Lindgren/Woodland Park Zoo
We recently announced that Uzumma, our 12-year-old western lowland gorilla, is expecting her first baby next March. The father is 20-year-old Kwame and this baby will be their first offspring together. Kwame arrived at Woodland Park Zoo in 2018 following the unexpected death of Leonel. The absence of a silverback (a male leader and protector) can be very destabilizing for a gorilla family, but Kwame’s confident leadership has unified the whole family group over this last year—enabling Uzumma and her whole troop to be ready for this exciting new chapter. We chatted with animal keeper Stephanie Jacobs to find out how our gorilla team prepares for a gorilla pregnancy and why they think Uzumma has what it takes to be a great first-time mother.

Kwame—silverback of the family, and father of Uzumma's baby. This will be their first offspring together. Photo: Jeremy Dwyer-Lindgren/Woodland Park Zoo

WPZ: First of all, how’s Uzumma doing? 

Stephanie: As she finishes her 2nd trimester, Uzumma is doing great. She exhibited a few food preferences in her 1st trimester—soaked chow as opposed to dry and cooked carrots over raw, and those have continued throughout her 2nd trimester. She has also been accepting more water from us (we give the gorillas big cups that they can gulp down in addition to the water that’s available to them 24/7 in their habitats), which had not been her habit prior to pregnancy. Her appetite has always been strong, but we’ve been offering her as much browse as we can in order to accommodate any subtle appetite fluctuations that may be occurring. The term “browse” refers to plant materials eaten by browsers—that is, herbivores or plant-eaters that eat the leaves, stems, bark and flowers right off the tree or bush instead of grazing on the ground. For our gorillas, browse is always a favorite and it’s also something that encourages natural, comfortable social behavior amongst the group. As a result, it not only quells any hunger pains, it also serves as a salve to any possible emotional shifts Uzumma or the group may be experiencing. 

Uzumma is 12—a great age for a mature young female to have her first baby. Photo/Dennis Dow/Woodland Park Zoo

WPZ: This is Uzumma’s first pregnancy, right?

Stephanie: Correct! At 12, Uzumma is a mature young adult female, which is a great age for a gorilla to have her first baby. Female gorillas can be reproductively receptive as young as 4 to 6, and in zoos are given birth control pills (the same kind as we humans use) to prevent any unwanted pregnancies. Experience has shown that fully mature females are more successful with the demands of motherhood.

In the gorilla unit, the first thing we do upon our arrival in the morning is collect urine samples from the females in their behind-the-scenes bedroom areas. This is a non-invasive method to test and follow their cycles.

Uzumma knows that she will be rewarded—with a favorite item from her diet—for sitting in a particular, elevated area in her room and urinating. We have a urine collection device, a modified piece of PVC, that she is conditioned to have held underneath her, allowing for a clean catch. All other gorillas in the group are rewarded for not interfering with whomever we’re collecting urine from. It was this training that allowed us to closely follow Uzumma’s cycle, and by documenting when and how often she and Kwame were seen mating we know when she was in estrus. Gorillas can breed all year round and not just seasonally—females menstruate and ovulate monthly, just like humans. There are very specific cues that indicate a female is in estrus. They become very assertive, standing right in front of the silverback, staring directly at him. These are behaviors that don’t happen at other times in a female’s cycle and some visitors may have even observed a few of them on exhibit. 

Uzumma's pregnancy testing stick—two lines means she's pregnant! Photo: Jeremy Dwyer-Lindgren/Woodland Park Zoo

Following her charts, we knew when the best time would be to test for pregnancy, and after a few negative cycles, we finally got a positive. Then we calculated her due date based on her documented cycles and estrus-based behavioral observations. She had shown strong estrus behavior, accompanied by several complete copulations, on June 28th and 29th, and again on July 7th. We are approximating conception to be around those dates. Gorilla gestation is similar to ours, approximately 8.5 months, which places Zum’s due date in early-mid March. Spring baby!

WPZ: A lot of planning goes into a gorilla pregnancy, tell us more about that!

Stephanie: We did plan for it, or at least hoped that our plans would come to fruition. We can only do so much—the gorillas have to do the rest! All of the females were on birth control upon Kwame’s arrival. This was intentional, as we didn’t want any surprise estrus behaviors to complicate the introductions. Once the group was cohesive, however, discussions began about who should be taken off birth control first.

All the adult females in Kwame’s group have breeding recommendations from the Gorilla Species Survival Plan—also known as the SSP. It is a program that monitors the variability of the gorilla gene pool for accredited conservation zoos, ensuring its diversity and a healthy, robust future for the population that lives in human care.

Since all three females had a breeding recommendation, our discussions focused more on personality and past experience to determine who should become pregnant by Kwame first. Of the three females, Uzumma is the only individual who was completely parent-reared. Her gorilla mother Amanda was exceptionally attentive and nurturing, and we are hoping those characteristics have been passed down through personal experience. Since good maternal behaviors are typically more predictable with mother-reared gorillas, we thought Uzumma may set an excellent example for Akenji and Nadiri, both of whom were partially hand-reared for the first few months of their lives because of their mother Jumoke’s inability to care for them.

Once it was agreed upon that Uzumma and her group were ready for this next stage, she was taken off birth control and the wait-and-watch began.

WPZ: You know all our gorillas very well. Has pregnancy changed Uzumma’s behavior at all? Do gorillas get morning sickness?

Stephanie: Uzumma is the dominant female in the group, a role which has so far continued through her 2nd trimester. We can’t use pregnancy as the excuse for her very, we like to say “passionate,” approach to life. She’s vivacious and energetic, and so far, those characteristics have remained intact. Gorillas do indeed get morning sickness, and their symptoms are similar to ours; no interest in eating, probably due to nausea or the gorilla equivalent, and accompanying exhaustion. Nadiri really struggled with morning sickness during her pregnancy with Yola and it was a challenge to get enough calories into her for a while, but so far, Uzumma hasn’t shown us any indications of such symptoms.

We have noticed her playing less with Yola, and keeping more to herself, but she can still be seen trying to get Kwame’s attention occasionally.

WPZ: What about Kwame and the other gorillas … does he/they seem to notice anything different?

Stephanie: Everything has been pretty status quo, so far. Kwame continues to be an excellent silverback who hasn’t shown favoritism for one female over another. He’s fair and reasonable and he and his group really seem to be thriving. One of the reasons we were interested in Kwame coming to WPZ in the first place was his calm temperament with little sister Kibibi at his prior facility. He was always gentle with her and appropriate when navigating the sometimes tumultuous social situations that occur in family groups. He had the reputation as a peace-keeper, rather than an instigator, a trait we knew would be necessary when leading our group of confident females and one little (albeit confident as well) Yola.

So far, Kwame hasn’t shown any observable change in behavior towards Uzumma, nor has anyone else, though it’s difficult to know what exactly they can sense amongst one another. They have ways of communicating that are observable to us, such as body posturing, facial expressions and vocalizations, but a lot of their interactions and understanding of one another goes beyond our comprehension. I wouldn’t be surprised if they sense that something different is happening.

In 2015, Nadiri gave birth to Yola—the last gorilla baby to be born at Woodland Park Zoo. Photo: Jeremy Dwyer-Lindgren/Woodland Park Zoo

A new mother’s status will increase in the group at the birth of her baby. We noticed this with Nadiri’s status when she had her baby Yola as part of Leonel’s group. Leo’s favorite female had always been Akenji, but with the addition of Yola, Nadiri found out that Leo was protective of them both. Nadiri was often seen sitting right next to Leo, and Akenji had to watch her step. Silverbacks protect new mothers and their babies—they don’t like an upset baby—even if mom is upsetting her baby the father is likely to display and lightly prod the mother, which causes her to pay attention to her baby and help it settle. 

WPZ: Thanks, Stephanie, for sharing the details of preparing for a baby gorilla and the inside scoop on how our mama-to-be is doing!

Click here to read part two of our Q & A with animal keeper Stephanie—and learn more about Uzumma’s pregnancy, getting ready for delivery and what comes next. 

One way you can help gorillas is to recycle old cell phones. Woodland Park Zoo partners with ECO-CELL to recycle minerals found in many handheld electronics, reducing the demand for mining in gorilla habitat. look for ECO-CELL drop boxes on zoo grounds. Photo: Woodland Park Zoo
Conservation Action for an Endangered Species

Every visit to Woodland Park Zoo supports conservation of animals in the wild—so when you come to visit Uzumma, Kwame and the others you are also helping support wild gorilla research and conservation. Woodland Park Zoo supports conservation efforts for the western lowland gorilla and mountain gorilla through the Mbeli Bai Gorilla Study and Dian Fossey Gorilla Fund. To help support these important projects, you can drop off used handheld electronics (cell phones, MP3 players, handheld games, e-readers, digital still and video cameras, GPS, portable hard drives, etc.) at the zoo. The handheld electronics are turned over to ECO-CELL, which operates a strict NO LANDFILL program and reimburses organizations for their recyclable contributions. ECO-CELL reuses mineral ore from these devices to reduce the demand for unsustainable coltan mining in the Congo that destroys habitat for critically endangered gorillas. The zoo directs funds from ECO-CELL toward the Mbeli Bai Gorilla Study, Dian Fossey Gorilla Fund and other great ape conservation projects.

Thank you for loving gorillas as much as we do and stay tuned right here for more on Uzumma and baby.