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Conceiving a Future for Cheetahs
by Phyllis McIntosh

In the wee hours of November 23, 2004—the day before Thanksgiving—head cheetah keeper Craig Saffoe sat alone in his office at the Smithsonian's National Zoo, staring nervously at a video screen. On it, he watched live images of Tumai, a four-year-old female cheetah (Acinonyx jubatus) that had been refusing her food, pace agitatedly around her enclosure. These are classic signs of an impending birth, but, like all female cheetahs, Tumai gave few outward indications that she was having contractions. It's a vulnerable time for a mother-to-be and her unborn cubs, Saffoe says, and loud vocalizing or other obvious birthing behavior could attract predators.

One of Zazi's cubs
One of Zazi's cubs, born April 14, 2005. (Jessie Cohen/NZP)

Suddenly, at 2:15 a.m., Tumai stood up, almost as if surprised, and started nudging something on the ground. Saffoe watched anxiously for a few moments until she lifted her head and he spotted a tiny cub wriggling around. Over the next nine hours Tumai, a first-time mother, gave birth to three more healthy cubs—two males and two females in all—the first cheetahs born at the National Zoo since it was founded in 1889.

As if this were not exciting enough, just five months later three-year-old Zazi, also a first-time mother, gave birth to five healthy cubs, two males and three females. A sixth cub was stillborn. The Zoo's population explosion accounts for about 20 percent of all cheetahs born in North America since the beginning of 2004. But most impressive of all, the nine cubs are thriving and being successfully reared by their mothers—no small feat for a species that in zoos is prone to difficulties at every stage of the reproductive process, from mating to mothering.

These cheetah moms make it look easy, but their breeding success is the result of years of painstaking research into the biology and management of cheetahs, much of it pioneered at the National Zoo. While both Tumai and Zazi mated with males at the Zoo, the Zoo's reproductive physiologists are poised to take the next step: determining how to use assisted breeding technologies such as artificial insemination and in vitro fertilization to help maintain a stable captive cheetah population.

Once plentiful throughout the Middle East and South Asia, cheetahs are now found only in Africa and in small pockets in Iran. Threatened by habitat loss, disease, and conflicts with humans and other animal predators competing for the same limited space, their numbers have dwindled to an estimated 12,000 to 15,000 in the wild. A healthy zoo population is essential to educating the public about these fascinating creatures—the fastest mammals on land, capable of reaching speeds of about 65 miles an hour—and the importance of protecting them in the wild.

Notoriously Difficult to Breed
The Zoo's Cheetah Conservation Station exhibit, which opened in 1992, was designed as a breeding facility, and the Zoo has been actively trying to breed the cats since 1999. At that time, many zoos faced the same challenges: getting cheetahs to mate and then determining why females that had mated did not conceive.

At first the low reproduction rate was blamed on the males, which were known to have very high rates of abnormal sperm, most likely because of inbreeding that followed a catastrophe some 10,000 years ago when the cheetah population may have dropped to just a few animals or perhaps even one pregnant female. But further study revealed that wild cheetahs were reproducing just fine despite the faulty sperm; the males were off the hook.

"We started focusing on the females and found that many were not regularly going into estrus," says Zoo reproductive physiologist JoGayle Howard. If two females are housed together and are not compatible, one will cycle and the other will shut down. Because signs of incompatibility are subtle—perhaps just a few hisses and growls—the Zoo has housed females separately since the Cheetah Conservation Station opened.

Tumai's cubs
Tumai's cubs, born November 24, 2004. (Jessie Cohen/NZP)

Other management techniques also proved critical in encouraging the cats to mate. Zoos looked at studies of cheetahs' behavior in the wild for clues to facilitating successful mating in zoos. In the wild, adult males (usually brothers) live in coalitions of two or three individuals and defend a single territory as a group, while females are nomadic and completely solitary except when they have a litter, Saffoe explains. And females decide when and with which males they will mate. When a female is in estrus, she enters the males' territory only when she is ready, and she also determines how long she waits for the males to come and find her. "In zoos we have historically tried to choose when we want females to breed and who we want them to breed with, and that does not work with cheetahs," says Saffoe. "Once zoos started paying attention to the behavior and biology of cheetahs and listening to what they were telling us, we started getting successful births."

Unlike domestic cats, which moan, spray, and roll when in heat, female cheetahs exhibit few outward signs when they are ready to mate. Chemical changes in a female's urine are one of the few indicators, and the scent of a female's urine signals to males that she is in estrus. When the Zoo wants to breed a female cheetah, keepers give her a few days to saturate the ground in an enclosure with her urine, and then introduce a male into the yard. "We wait for the males to tell us the female is in estrus," says Saffoe. If the time is not yet right, the male may just walk around, sniff, and lie down. But if the female is in estrus, "it's like someone flicked a light switch," Saffoe says. The male chirps, yelps, and runs around the yard. If the female is then allowed into the adjacent yard, he usually starts stuttering, a low throaty sound like a pigeon cooing, which is a direct solicitation to the female to mate.

While the males make their intentions well known, the females' signs of interest are much subtler, Saffoe says. If the female raises her tail and exposes her genital area, or lies down and starts rolling, she may be willing to mate. But even those behaviors are not foolproof indicators. "The trick is in knowing whether she's rolling because she's interested in mating or because her back itches," says Saffoe. "We have to spend a lot of time looking at those signs and learning to interpret them."

Before Tumai's and Zazi's pregnancies, there were nine natural matings at the National Zoo. Two females also were artificially inseminated via a method developed by Howard in which a thin rod called a laparoscope is inserted through a tiny incision in the cheetah's abdomen to deposit semen directly into the uterus. Throughout North America, this method has achieved a 45 percent pregnancy rate and produced 19 cubs since the early 1990s. But with the National Zoo's cheetahs it failed.

Over and over, hopes were dashed when signs of pregnancy proved to be false alarms. Once a female cheetah has mated and ovulated or been artificially inseminated after a hormonally induced ovulation, her body switches into pregnancy mode. Hormones rise tantalizingly for about 60 days—two-thirds of the way through the normal gestation period of about 90 days—then drop if the cat is not pregnant. Because cheetahs excrete the hormones used to determine if they are pregnant in their feces rather than their urine, confirming a pregnancy is a complicated process. Fecal samples must be collected up until about 70 days after mating to make sure hormone levels are accurately reflected. The samples must be dried in a giant vacuum freezer for about two weeks, then sent to the hormone lab at the Zoo's Conservation and Research Center (CRC) in Front Royal, Virginia, and the results reported back to the Zoo, which takes another week. By the time keepers get conclusive test results, months of uncertainty have elapsed, and the gestation period is nearly over.

Why weren't the Zoo's cheetahs conceiving? The females were housed separately and were cycling and breeding, so management was not the problem. "Age was the only thing we could think of," says Howard, so she and Jack Grisham, the Zoo's associate curator and coordinator of the cheetah Species Survival Plan, analyzed data on cheetah births at other facilities back to 1970. They found that the majority of births, whether from natural mating or artificial insemination, occurred in females between the ages of three and eight. Fertility dropped significantly between ages six and eight, which explained the failures in the Zoo's cheetahs, all age seven or older. Tumai and Zazi, both of prime breeding age, arrived from other zoos in spring 2004, and a year later the Zoo had two litters of cubs.

During those pregnancies, keepers learned that an animal's weight may be as reliable a sign of pregnancy as fecal hormone tests and can yield results more quickly. "Weight follows the same pattern as the hormones," Saffoe says. Up to 60 days after mating, females gain weight, and in each false pregnancy their weight has dropped between 60 and 70 days after mating, Saffoe says, noting that "what made us relatively certain Tumai was pregnant was that her weight shot up after day 60." Zazi followed the same pattern.

Cheetah Parenting
Conceiving and giving birth are just the first hurdles. Cub rearing does not always come naturally to cheetah moms, which incidentally get no help whatsoever from the cubs' fathers.

"What is astounding about these litters is that all the cubs born alive have survived," Saffoe says. "There's a huge potential for at least one cub to die or be neglected or for something to go wrong. It's phenomenal to have nine healthy cubs that the moms attend to just fine." Zazi is such a good mother that she even cleaned and moved her stillborn cub as though it were part of the living litter.

Zazi and cub
Zazi (pictured, with cub) and Tumai are excellent mothers. (Jessie Cohen/NZP)

Saffoe attributes part of the mothering success to good natural instincts and the fact that both Tumai and Zazi were reared by their mothers rather than by humans. But the Zoo can take some credit as well. Keepers decided long ago that, if possible, they would adopt a hands-off policy during the first few weeks to allow mother and cubs to bond. To avoid imprinting the newborns with human scents or inadvertently transmitting diseases that their undeveloped immune systems could not fight, even the Zoo's veterinarians did not handle the cubs until they were four weeks old.

Peace and quiet are also essential to mothering success, the Zoo staff believes. "The cold, hard fact is that it's not terribly uncommon for cheetah mothers—or any carnivores—to destroy their young," Saffoe explains. "The statistics are probably a little higher for cheetahs, because they're very sensitive animals and easy to scare. Anything from a thunderclap to a truck driving by to a door slamming could make the mother snap and turn on the nearest thing to her." To avoid disturbing or startling the new mothers, the entire Zoo mobilized to limit staff and volunteer access to the cheetah enclosures and to reduce public traffic on the walkway in front of the nursery yard. Trash collectors help keepers take waste out to the roadway, so trucks don't have to come too close to the yards.

The Cubs' Future
In the wild, cheetah cubs stay with their moms for about 18 months. After the mom and cubs separate, siblings remain together for perhaps another six months until they approach sexual maturity. The females then go off to live alone, while brothers usually form a permanent coalition, find a territory, drive off any other male cheetahs they find there, and stake it out as their own.

In zoo environments, cheetah cubs don't need to perfect the same hunting and survival skills their mothers would teach them in the wild, so separation occurs earlier, usually when the cubs are between nine and 12 months old. When keepers notice that mom is vocalizing less and lying farther and farther away from the cubs, they will remove her for an hour or so at first, then for longer periods until the separation is complete. Once they see a similar separation occurring among the cubs themselves, the females will be housed independently, and brothers will likely stay together as a coalition wherever they go.

By age two most, if not all, of the cubs likely will be sent to other zoos. The Cheetah Conservation Station is currently filled to capacity, and the Zoo will want to breed Tumai and Zazi again because they have a proven track record.

Ultimately, the cubs' fate depends on recommendations from officials of the cheetah Species Survival Plan (SSP), a cooperative management program among zoos that collectively house the 300 cheetahs in North America. The goal of the SSP is to move animals and manage breeding to ensure the greatest genetic and age diversity possible within the population, says SSP coordinator Jack Grisham. Every 18 to 24 months, the SSP surveys zoos with cheetahs, ascertains their needs, and writes a master plan that makes recommendations on moving cheetahs from one facility to another. "We'll probably make recommendations this winter on where our cubs go," says Grisham.

The Future of Cheetah Conservation
In hopes of expanding its cheetah program and giving more cats the space and seclusion they need to reproduce successfully, the Zoo is designing and seeking funding for a state-of-the-art breeding and research facility at its Conservation and Research Center. Planned to comfortably hold at least 14 cheetahs, the new quarters ideally would become one of several regional facilities where the bulk of captive breeding would take place, says assistant curator Tony Barthel.

Some cheetahs would remain at the Zoo's Rock Creek facility to educate the public about cheetahs and the Zoo's conservation efforts on their behalf, Barthel notes. As for future cubs being on exhibit at the Zoo, Barthel says he would be "very interested in exploring" whether a pregnant cheetah or mother with young cubs could be safely moved between facilities. "We do know what kind of breeding facility we need to build at the Conservation and Research Center, we know how to manage the cats, and if we can get the new facility built quickly enough, we know how to fill it with cats," he adds.

The long-term future of the population of cheetahs in zoos depends on continued research into the basic reproductive biology of cheetahs and ways to assist breeding for greater genetic diversity and an increased population in the species. In the mid-1990s, Howard and other National Zoo scientists, working with scientists from other institutions, used artificial insemination with fresh semen to achieve a total of seven cheetah pregnancies at three facilities in Texas and Michigan. After those successes, Howard and a team of Zoo scientists traveled to Namibia, the southern African nation with the largest wild cheetah population in the world. There they showed they could safely catch wild cheetahs and anesthetize them to collect semen for freezing. The team then worked with the cheetah SSP to select females in U.S. zoos for insemination with the frozen Namibian sperm, an effort that resulted in three pregnancies, one in Florida and two in New Mexico.

Once laparoscopic artificial insemination proved successful with both fresh and frozen sperm, Zoo cryobiologist Budhan Pukazhenthi took the lead in developing new methods of freezing and banking cheetah semen for future use. Reproductive physiologist Adrienne Crosier continued the work between 2002 and 2005 at the African headquarters of the Cheetah Conservation Fund (CCF), which works to protect cheetahs and their habitat in Namibia.

Cheetah cubs in the wild
National Zoo scientists study cheetah reproduction in Namibia.

Using non-releasable resident cheetahs at CCF as sperm donors, Crosier further perfected freezing techniques and then began collecting samples from wild-caught cheetahs that were brought in for medical examination and treatment before they were released back into the wild. In the three years she worked at CCF headquarters, she banked 140 sperm samples from about 60 wild-born animals and taught her African colleagues at CCF how to carry on with the project after she left. The collected sperm is part of the Genome Resource Bank at CCF, which stores genetic material from cheetahs as a precaution against catastrophes such as an epidemic that would wipe out much of the population. As Zoo scientists have shown, frozen sperm from wild cheetahs also can be used to enhance the genetic diversity of cheetahs in zoos.

Over the next few years, National Zoo scientists will study aging in female cheetahs and explore the potential of in vitro fertilization for allowing older females to reproduce. Almost half of the females in North American zoos are over eight years of age, and many of them have never reproduced. "We want to salvage their genes. But nobody has ever looked at things like menopause in a cheetah, or indeed in any carnivore," says Crosier. Zoo scientists will investigate whether eggs from older females are viable, or whether, as with women over 40, there are problems with uterine health or fetal abnormalities in older female cheetahs.

Researchers will use ultrasound and laparoscopy on older females to examine the ovaries and uterus and will collect eggs to study their quality. "Older cats may have uterine cysts that would prevent a fertilized egg from implanting," says JoGayle Howard, "but if we're able to get embryos through in vitro fertilization, we could freeze them or transfer them to a younger cheetah and get some representation from those older females that are genetically valuable but have never reproduced."

All of these efforts are directed toward one end: saving cheetahs in the wild. "The best way to ensure that fewer people contribute to the destruction of the wild population is to bring cheetahs near and dear to people's hearts," says Craig Saffoe. He believes that seeing cheetahs at zoos educates people about their plight and helps them understand how cheetahs are an important part of the world around us. But the future of cheetahs in zoos rides on the success of zoo breeding programs. "The only way to guarantee that cheetahs will be in zoos for the long-term is by breeding them in zoos," says Saffoe, who notes that the Zoo does not remove cheetahs from the wild for its breeding programs. "We want to make sure that generation after generation is able to learn about these beautiful animals and to appreciate them the way we all do."

—Phyllis McIntosh is a freelance writer and a volunteer interpreter at the Cheetah Conservation Station.

ZooGoer 34(5) 2005. Copyright 2005 Friends of the National Zoo.
All rights reserved.

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