The National Zoo’s Elephant Reproduction Project and its associated Endocrine Lab, led by National Zoo scientist Janine Brown, studies the biology of elephants through basic and applied research to enhance species conservation and management.
Elephants in zoos breed poorly or not at all. The current populations of elephants—both African and Asian—are not reproducing fast enough to replace themselves, and few elephants are being imported from the wild. Within the next 50 years, there may not be elephants in zoos. What a loss—many people develop their first interest in wildlife from experiencing the wondrous elephant.
What’s the Problem?
There are several. In zoos with both male and female elephants, potential pairs are sometimes incompatible or not the most genetically suitable for breeding together. In addition to the obvious challenges involved in moving 15,000-pound animals from zoo to zoo for breeding, is the fact that few zoos are equipped to handle adult males, whose breeding behaviors include prolonged periods of aggressive, potentially destructive and dangerous behavior.
In addition, many female elephants in zoos do not display normal estrous cycles. In fact, some don’t cycle at all, and this precludes their being interested in mating and their being fertilized, even by artificial insemination. Brown and Elizabeth Freeman are examining the factors that lead to females’ not cycling so they can find ways to restore normal reproductive cycles. Their results so far.
Still artificial insemination is a critical tool for increasing reproduction in zoo elephants. This technique gets around problems of mate incompatibility while maximizing genetic management. It eliminates the need to transport elephants from zoo to zoo, and thus reduces stress and lets females remain with their herds.
The key to successful artificial insemination is timing. The insemination must take place during a two-to-three day window around the time of ovulation when fertilization is most likely. Brown and her partners discovered how to accurately predict ovulation in female elephants by monitoring their hormones.
For most elephants, hormones are monitored in blood samples collected weekly. But, the Endocrine Lab scientists can also measure steroid hormone metabolites excreted in urine and feces. The data they collect and analyze are now routinely used to time breedings, especially those using assisted-breeding techniques such as artificial insemination.
The National Zoo's Endocrine Research Lab has helped zoos use artificial insemination to perform more than a dozen assisted breedings, several of which resulted in pregnancy. The Lab also provides a host of other services to other zoos to help increase reproduction in elephants in North American zoos. Endocrine Lab Services
Apart from their use in timing insemination or mating, hormone patterns indicate which animals are cycling, enable us to monitor pregnancy and predict impending birth, aid in diagnosing certain diseases such as thyroid and adrenal function. Other hormone analyses can be used to measure animal well-being, allowing zoo environments to be enriched to enhance welfare and chances of successful reproduction.
This research is one of the highest priorities of the American Zoo and Aquarium Association’s Elephant Species Survival Plan.