August 26: Utamu's Expecting
We are excited to announce that Utamu, an 18-year-old chimpanzee at the Saint Louis Zoo, is pregnant and due to give birth this fall at Jungle of the Apes. The pregnancy is based on a breeding recommendation by the Association of Zoos and Aquariums Chimpanzee Species Survival Plan.
Photos: Ethan Riepl
September 2: Getting to know Utamu
September 9: Discovering a pregnancy
So just how did the primate care team find out that Utamu was pregnant you might wonder?
It might be helpful to begin with a little background information on chimpanzee female reproductive cycles.
Chimpanzees have about a 36-day reproductive cycle. The primate care team is able to track this cycle for all the female chimpanzees as part of our daily husbandry monitoring. When a female is ovulating or “can become pregnant,” she develops what is called an estrus swelling. Her behind swells up looking a little like a small inflated pink balloon. For the rest of her cycle, this area is deflated and has loose pink skin. Female chimpanzees also menstruate during their cycle. So if one of these events is missing or late, it can often be the first indication of a potential pregnancy to the primate care team.
Utamu with full estrus swelling.
Rosebud with no estrus swelling.
How do we confirm a chimpanzee pregnancy?
We use an at home pregnancy test, the exact same type that you would use to confirm a pregnancy for a human! Utamu is trained to urinate when asked and this can then be collected and applied to a home pregnancy test.
We also have a secondary method to confirm pregnancy:
You might not know this but the Saint Louis Zoo has its own endocrinologist, Corinne Kozlowski, Ph.D., and an endocrinology laboratory. One way to have a secondary verification of a chimpanzee pregnancy is to compare progesterone levels of a suspected pregnant chimpanzee to progesterone levels of a non-pregnant female chimpanzee. Progesterone levels rise during pregnancy. The care team is able to submit fecal samples from the chimpanzees collected during daily cleaning to the lab where Dr. Kozlowski can evaluate them.
Continue to follow Utamu: Path to Motherhood to learn more about Utamu’s pregnancy and the work being done by Saint Louis Zoo staff in preparation for the upcoming birth.
September 16: Being a Chimpanzee Mom
The length of a chimpanzee pregnancy is just slightly shorter than that of a human pregnancy at 8 months. Chimpanzee moms are very hands-on for the first several years of the infant’s life and typically have intervals of 4 to 6 years between births because of this. Even when a chimpanzee mother has another baby, the older siblings will typically still stay close to mom, giving the juvenile female offspring the opportunity to learn important skills about caring for infants that will aid them with their own offspring in the future.
Chimpanzee babies will typically nurse from their mother for up to 5 years, even after regularly eating solid foods. Chimpanzees are born with very strong grasping abilities, as they need to cling to their mother’s belly as she climbs and moves around. As they get older they will transition to riding on their mom’s back. Eventually they will start to venture off of mom to explore and play, but always staying in close range and still climbing on her back for a ride when moving from place to place.
Being a chimpanzee mom is a very important and difficult job. They may have help from other members of the troop but they are the main caretaker and are responsible for keeping their offspring safe. Mother chimpanzees are also responsible for teaching their offspring what food to eat, how to act in the social hierarchy, how to use tools, how to build nests, and a lot of other vital information that will help the young chimpanzee survive and thrive. We are looking forward to seeing what an amazing mom Utamu will be!
Utamu and Rosebud
Utamu and Rosebud
Beauty and Utamu