Historically, says Brown, zoo biologists went to Asia or Africa to replace lost animals. But dwindling wild populations and new legal restrictions on endangered animals have led zookeepers to explore captive breeding as an alternative. The first known captive-born Asian elephant to survive infancy in North America was Packy, who was delivered in 1962 at the Oregon Zoo. The continent’s first captive African birth came when a female named Little Diamond was born in 1978 at Knoxville Zoological Gardens. All told, only 129 Asian elephants and 38 African elephants have been born in North America since 1962. The infant mortality rate is above 30 percent. To make matters worse, a mystery disease killed at least 7 of the 34 Asian elephants born in North American zoos between 1983 and 1996. Among the dead was 16-month-old Kumari, who died in 1995 at the National Zoologica lPark in Washington, D.C. Through careful sleuthing, National Zoo pathologists Richard Montali and Laura Richman discovered that Kumari had died from a previously unknown form of the herpes virus. Richman, who now works for a private company, and Montali believe that one way Asian elephants pick up the disease is from contact in zoos with African elephants, which can carry the disease without ill effect. U.S. zoo-keepers have saved the lives of three sick animals by administering Famciclovir, an antiviral drug also used to fight herpes in humans.
Meanwhile, wild elephants have become even scarcer. In Africa, authorities estimate that the elephant population has dropped from 1.3 million in the 1970s to between 270,000 and 500,000 to-day. In Asia, elephant populations have dropped from an estimated 100,000 in 1900 to between 38,000 and 48,000 today. Among the threats to wild elephants are poachers, who kill the animals for their ivory tusks and meat; roads and railways that cross elephant migration routes; and farmland, which is replacing stamping grounds. In some places, farmers have killed elephants that have trampled crops and fences. “Elephants get killed every year,” says Steve Osofsky, senior policy adviser for wildlife health at the New York-based Wildlife Conservation Society.
North American zookeepers hope to breed elephants not only to curb the need for further imports but also to develop new reproductive techniques that can be applied to wild herds. But captive breeding is fraught with physical obstacles and philosophical quandaries. Zoos cannot easily replicate life in the wild, where females generally live in matriarchal groups of 8 to 12 members that are usually related. In contrast, captive females often end up in small groups of unrelated individuals. Some groups contain Asian and African species. In addition, many zoos are unable to accommodate a full-grown bull, which can weigh up to 16,000 pounds and can be aggressive toward other elephants and zookeepers.
For years, some zoos have facilitated elephant courtship by loading a female onto a truck, driving her to a breeding bull and hoping for the best. The hope was usually forlorn. Infertility is a problem. Females older than 30 who are conceiving for the first time have a high incidence of stillbirths, and about 15 percent of captive Asian females and 25 percent of captive Africans of calf-bearing age are known as flatliners, meaning their reproductive hormone cycle is inactive.
Artificial insemination, which has worked well on many other species, is a challenge with captive elephants. Designing a means of navigating an elephant’s eight-foot-long, curving reproductive tract and timing an elephant’s estrus are among the obstacles. (An elephant’s period of fertility—only two or three days out of every four-month estrus cycle—has been difficult to predict until recently.) In addition, facilities without a resident male must import bull sperm, which remains potent for only 24 to 48 hours. (Elephant sperm usually loses its viability when frozen, so establishing a sperm bank is not an option.) At the National Zoo, which doesn’t have a bull, veterinarians must obtain samples from several bulls at different locations across North America and must time inseminations precisely. “It’s like cooking a huge meal,” says Brown, adding, “It takes a lot of planning to make sure that all the different courses come out at the right time and it’s all hot when you go to serve it.”