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March/April2010 cover
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Cheetah Challenges

The Smithsonian’s National Zoo has become a leader in the challenging field of cheetah reproduction.

By Phyllis McIntosh

You might call it speed dating, cheetah style. A male strolls down an alleyway dubbed Lovers’ Lane and sniffs around yards where females are hiding out of sight. He tries to catch a whiff of a receptive female. If he announces that he likes what he smells, he and the female may introduce themselves through a fence. If she likes him too, she will roll on the ground or exhibit some other breeding behavior. Keepers will then make sure the couple gets a chance to meet—and, fingers crossed, mate.

The site of these amorous activities will be the 8.5-acre, state-of-the art cheetah facility, funded by your contributions, at the Zoo’s Front Royal, Virginia, campus. With the flexibility to shift cats between Front Royal and Washington, D.C., where the Zoo staff have successfully produced two litters, the Zoo can optimize care and breeding of its cheetahs and is poised to become a national leader in rebuilding and maintaining the captive population.

A cheetah surveys its enclosure at the Zoo's Front Royal, Virginia, campus. (Mehgan Murphy/NZP)

Cheetahs in Crisis

Cheetahs need all the help they can get. Numbers in the wild have dwindled to an estimated 12,000, the result of habitat loss and competition with people and other animal predators for limited space. The captive population is also in crisis, despite a Species Survival Plan (SSP) that ranks and recommends individual cheetahs for breeding. “In the effort to genetically manage a group of animals, you sometimes end up with feast or famine, and we’re definitely in a famine now,” says Craig Saffoe, a biologist and longtime cheetah keeper at the Zoo. Of the 249 cats in American and Canadian zoos, only 16 percent have ever reproduced.

Part of the problem is an aging female population. Recent research has shown that fertility declines dramatically in females between six and eight years of age. Females up to age 12 still cycle and produce hormones. Their ovarian pathways are intact, and they willingly mate. Yet they do not get pregnant, most likely because of problems such as cysts, fibroids, and buildup of fluid and tissue in the womb. Females above the age of six that have not given birth are unlikely ever to conceive. Even for those who have reproduced, chances of subsequent pregnancies diminish considerably when three or four years have elapsed since their last litter. Among North American cheetahs, only six proven breeding females currently are under the age of eight.

The sleek cats—famous as the fastest animals on land—are also notoriously difficult to breed. “Everything about their biology is unique,” says Adrienne Crosier, a cheetah research scientist in Front Royal. “Estrous cycles are short and inconsistent among females and even in the same female. Most females do not show outward signs of estrus, and there may be subtle changes in behavior from cycle to cycle.”

Keepers know that when females are housed together, a dominant female may “shut down” another’s estrous cycle. Now, Zoo biologists suspect there may be some suppression among males as well. For example, Ume, the father of five cubs born at the Zoo in 2005, exhibited no breeding behavior until two unrelated males died.

As if all these were not hurdles enough, sometimes genetically desirable pairs simply aren’t interested in one another.

Boosting Breeding

Because about 80 percent of births since 1960 have occurred at large regional breeding centers with the space, staff, and experience to best manage cheetahs, SSP scientists are now focusing breeding efforts on a handful of regional centers. The National Zoo is one of six such centers, along with White Oak Conservation Center in Florida, Fossil Rim Wildlife Center in Texas, The Wilds in Ohio, San Diego Wild Animal Park in California, and Wildlife Safari in Oregon.

Newest of the six centers, the cheetah facility in Front Royal is modeled on the design and breeding strategies of Fossil Rim and successful centers in South Africa. With 14 enclosures—four at one end and ten flanking the central alleyway— keepers can visually separate males and females prior to mating investigations and introductions. With cheetahs, absence, or at least separation, can indeed make the heart grow fonder.

The facility can comfortably house 20- plus cats, including mothers with cubs and groups of brothers, known as coalitions. Coalition members form a tight bond and remain together for life both in the wild and in captivity. The goal is to keep some yards empty at all times to maintain the flexibility to move cats as needed for breeding and their own welfare. “If one of the boys in a coalition has a minor injury, you but he can’t be in with his brothers either, so we could put him right next door where they can still see each other,” Crosier says. “Or, if we have a litter of four or five cubs and they’re a year old, we might need a couple of yards for them.”

The staff closely monitors both biology and behavior in all the cats. Fecal samples yield important hormonal clues about stress levels and readiness for breeding. “If we’re trying to keep track of a certain female to see if she’s cycling, we need to get at least five samples a week, because the estrous cycle is so short that you can easily miss it,” Crosier explains.

Biologists also assess the temperament of individual cats to make sure that females especially are in a settled, relaxed situation, crucial for breeding. At Front Royal, one cheetah enjoys her own space and likes to retreat to the back of the yard where no one can see her. A young, more anxious cat, on the other hand, is comforted by the presence of an older female next door.

Breeding efforts will focus first on two five-year-old females highly recommended by SSP scientists and on three brothers, recently transferred from the downtown Zoo. The brothers are genetically valuable because their parents, orphans at a captive facility in Namibia, were born in the wild.

The decision to move the males from Rock Creek to Front Royal accords with recent behavioral research, which suggests that it is better to move males among zoos for breeding and leave females in place. It can take some females a long time to adapt to new surroundings; meanwhile, biological clocks are ticking. Males, especially coalition members, tend to adjust more easily, perhaps because they have each other.

Because of the current crisis in the captive population, seven of the Zoo’s eight cheetahs are in the breeding mix. The staff will even attempt to mate Zazi, an eight-year-old who gave birth to five cubs in 2005 but failed to conceive following two subsequent artificial inseminations
“We know from her fecal samples that she is still cycling, and because she’s had a litter, we think there’s some protection on her uterus,” Crosier says. “Plus, she was an excellent mom. If nothing else, it will be good for the boys to witness the behavior of an older, experienced female.”

So far, biologists have been stymied by the brothers’ apparent lack of interest in mating. At four years of age, however, they are still young. Saffoe points to several captive males in the past which didn’t start exhibiting breeding behavior until they were seven, eight, or nine.

Looking to the Future

At the same time that the Zoo is trying to coax cheetahs into breeding, scientists and veterinarians are also exploring other ways to boost the captive population. A major goal is to salvage the valuable genes of aging females who have never reproduced by fertilizing their eggs in the lab and transferring them to a younger cat.

The Smithsonian's National Zoo hopes to repeat its success at breeding cheetahs, which are vulnerable to extinction. (Mehgan Murphy/NZP)

“We know the eggs of older cats are mature and do fertilize, but we have to figure out how to get a four-year-old female hormonally ready to receive fertilized eggs,” Crosier says. “We’re looking at different hormones and combinations of hormones, but this first step will take a couple of years.”

The Zoo is also pursuing ways to import non-releasable, wild-born cheetahs from Africa. Another, more likely scenario is to obtain frozen sperm and embryos from wild-born animals. Already, some 300 African sperm samples and a handful of embryos are stockpiled at the Cheetah Conservation Fund in Namibia, which works closely with the Zoo. Although there may be complicated paperwork involved in importing such genetic material, it will likely be easier than bringing in live animals.

Since 1992, when the Zoo opened its highly successful cheetah exhibit, the Zoo has had a strong cheetah program, Saffoe notes. “Now, with the addition of a science facility, we will be even stronger leaders in cheetah conservation,” he says. “We have a combined staff of research scientists working toward improved natural and assisted reproduction, husbandry scientists who are making huge strides in recognizing how cheetahs should be managed, and vets who are learning tremendous amounts about cheetah illnesses and how to treat them. You don’t find many facilities that have that many pieces of the puzzle within the same walls.”

— Freelance writer Phyllis McIntosh has been a volunteer interpreter at the Zoo for eight years, including six at the Cheetah Conservation Station.

 

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Smithsonian Zoogoer 39(1) 2010. Copyright 2010 Friends of the National Zoo. All rights reserved.