July 24, 2018

By Corinne Kozlowski, Ph.D.

On November 26, 2017, Bingwa, a 4-year-old female cheetah, gave birth to eight healthy cubs at the Saint Louis Zoo. While the birth may have come as a surprise to the St. Louis community, scientists in the Saint Louis Zoo Endocrinolgy Lab had been closely following Bingwa’s hormone levels for several months to ensure that she had a healthy pregnancy.

While pregnancy tests for humans are easily purchased at any drug store, commercial pregnancy tests are not available for Zoo animals. Additionally, females often hide behavioral indicators of pregnancy and do not start showing until close to their due date, which can make it very difficult for keepers to determine if an animal is pregnant. However, early pregnancy detection is important as it allows animal care staff to provide the mom-to-be with everything she needs for a healthy pregnancy and safe delivery.

Scientists in the Endocrinology Lab have developed methods for detecting pregnancies for many species here at the Zoo. Our tests usually involve measuring concentrations of the hormone progesterone, which increases substantially when a female is pregnant. For humans, progesterone is usually measured by collecting a blood sample. However, collecting blood samples from animals at the Zoo can be difficult. Fortunately, concentrations of progesterone can also be accurately measured in samples collected non-invasively, including saliva, urine and feces. Of these, feces samples are the easiest to obtain and best for our animals, as collections do not disturb the animals. Thus, much of the work in the Endocrinology Lab involves measuring hormones in fecal samples.

Endocrinology Lab scientists had been regularly following Bingwa’s hormone concentrations through fecal sampling since her arrival in 2015. We first measured her cortisol levels to assess how well she had settled into to her new home in St. Louis and continued to monitor her estrogen levels to determine that she was having healthy reproductive cycles. In August 2017, we discovered that Bingwa’s progesterone concentrations had increased. This timing matched an introduction period with male cheetah Jason, indicating that she had mated and ovulated. Unlike humans, who ovulate (release an egg) monthly regardless of mating, cheetahs only ovulate after mating (known as induced ovulation). After ovulation, progesterone concentrations remain elevated for about two months and then decline if a mating was infertile. However, if a mating was fertile and a female is pregnant, her progesterone concentrations remain elevated until delivery, which occurs around 100 days after mating.

Excitement grew as we continued to monitor Bingwa’s progesterone concentrations throughout the fall. In October, we determined that her progesterone concentrations were still elevated. This was more than two months past her mating date, indicating that she was indeed pregnant. We immediately informed the animal care and veterinary staff who then began preparing for the birth and delivery. A little over a month later, Bingwa gave birth to her eight cubs.

We continue to follow Bingwa’s hormone levels, as well as those for many of the Zoo’s large felids, bears, elephants, primates and ungulates. By monitoring reproductive cycles, pregnancies, and measurements of well-being, we provide information that allows the Zoo to deliver the highest levels of care to our animals. We enjoy all of the testing performed in the lab, but diagnosing pregnancies is certainly one of the most exciting aspects of our work.

Now, Bingwa’s eight cubs – affectionately referred to as the Bingwa Bunch – can be seen out at their habitat in River’s Edge. The five females and three males are playful, healthy young cheetahs. This birth is a testament to the Saint Louis Zoo’s 44-year commitment to saving cheetahs in the wild. Read more about our cheetahs here.

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