Hooked on Elephants
by Janine Brown
When I was growing up, my favorite stuffed animal was an elephant named Dumbo. By the time I started high school, he had no eyes and almost no stuffing in his trunk. Little did I know that many years later I would become an elephant expert.
I wish I could say that was my plan all along, but it wasn’t. In graduate school, I studied reproduction in dairy cattle and became an endocrinologist— a person who studies hormones.
By 1988, I was working at the Uniformed Services University in Bethesda, Maryland, when I got a call from the Smithsonian National Zoo’s elephant manager asking if I could measure hormones in elephants. At the time, the Zoo had three Asian elephants—Shanthi, Ambika, and Toni—and one African elephant, Nancy. I had no idea how to work with elephants, but I said “yes.” The goal of the study was to find out if Shanthi, then 12 years old, had reached puberty. I played around with several techniques I had learned in graduate school and found an assay that could measure progesterone, a major reproductive hormone. The keepers would send blood samples from all the elephants to my new lab at the Zoo’s Conservation and Research Center (CRC) in Front Royal, Virginia. I was able to determine that Shanthi’s hormones did indicate that she had reached puberty, and she was sent off to Syracuse, New York, to breed with a bull named Indy.
By that point the work had really piqued my interest. Back then, we knew almost nothing about the reproductive biology of elephants, especially their hormones. By examining all of the elephants at the Zoo, I found that the elephant has the longest fertility cycle of any mammal—about 3 to 4 months. I was intrigued by the variability in cycle lengths among the three Asian female elephants; Ambika had the shortest at 14 weeks, Toni the longest at 17 weeks, and Shanthi was in between at 15.5 weeks. Nancy, on the other hand, was not cycling at all, and she was producing milk from her mammary glands despite the fact that she had never been bred. This was very strange. What could it be? I knew of only two hormones that could initiate milk production: estrogen and prolactin. We determined her estrogen levels were normal, so we focused on prolactin. After a year, I developed an assay to measure prolactin in elephants. It turned out that Nancy did indeed have elevated levels of prolactin, which meant she would never conceive.
By this time, Shanthi was pregnant in Syracuse, so I decided to monitor her pregnancy. This monitoring led to some important findings that have made our Zoo a leader in elephant reproduction. First, we found out that our new prolactin assay was perfect for diagnosing pregnancy. We also learned that progesterone declines to baseline two to five days before birth, which meant we could predict the time of an elephant calf’s birth quite closely. This measure has since become a vital birthing management tool. Another big development was our discovery of a unique hormone pattern in elephants that lets us predict three weeks in advance of when a female is going to ovulate. This knowledge is key to timing artificial insemination (AI), and is how we enabled Shanthi to become pregnant with our young male Asian elephant Kandula.
As the National Zoo became known for our work on elephant reproduction, other zoos contacted me to assess their female elephants, too. Then the Elephant Species Survival Plan committee asked me to be its reproductive advisor to help identify viable breeding candidates. By 1994, I established a “fertility clinic” that focused specifically on elephant reproductive health. Our team now monitors more than 120 female elephants at some 30 institutions. We help zoos determine if their females are cycling normally, when to time natural mating or AI, if an elephant is pregnant, and when she is going to give birth.
This year, as Ambika turns 60, we continue to learn from her. As one of the oldest Asian elephants in North America, and the oldest one being hormonally monitored, she is helping us determine whether elephants experience menopause like humans do. We know reproduction slows down in wild elephants once they reach about 50 years of age, but based on what we see with Ambika, they may not actually stop cycling. She continues to plug along with her 14-week cycles. With 20 years of hormone data on Ambika, she is one of the best-studied elephants in the world.
As for me personally, the best part of my job has been getting to know our elephants. Each one is unique. Shanthi is a bit lazy, but well-tempered and a terrific mother. Ambika is reserved, but is also known to have a stubborn streak. My favorite story about Ambika is when we made elephant footprints several years ago for a fundraiser. We had to paint the bottom of the elephants’ feet and have them step on a piece of paper. Shanthi dutifully stamped out several dozen footprints. Ambika, on the other hand, would start to put her foot down, but as soon as she was close to the paper she would suddenly move it away. We ended up with many partial footprints and finally gave up. By the twinkle in Ambika’s eye, she knew exactly what she was doing.
Our elephants and those I work with throughout the country are my extended family. I am so proud to be part of the elephant program at the National Zoo, and wouldn’t want it any other way.