Cheetahs don't roar, like other big cats. They purr.
It's a deep, rumbling vibration that is simultaneously tranquil and terrifying. You can sense their calm, but you can also sense their power. I was transfixed as I listened to Nick, a five-year-old male cheetah, purring happily inches from my face on the other side of a chain-link fence.
It was a cold, grey day in the hills of Virginia, more than 7,000 miles away from the cheetah's natural habitat in the dry grasslands of sub-Saharan Africa. Nick paced the fence line, my view of him obscured by some plastic slats woven through the links.
"He's really hard to get pictures of because he's always right on the fence," explained Adrienne Crosier, a biologist and the head of the cheetah breeding program at the Smithsonian Conservation Biology Institute (SCBI) in Front Royal. She told me Nick, hand-reared for a few weeks as a newborn, is particularly fond of people.
"He always wants to come see you," she said, Nick's purr thrumming continuously.
Nick has spent his entire life in these hills at SCBI, where 21 endangered species are bred and researched. The cheetah program is considered one of the facility's biggest success stories. Over the last five years, SCBI has been responsible for bringing 34 healthy cheetah cubs into the world and contributing a wealth of scientific research to our understanding of the species. The goal is to gain knowledge that will help conserve cheetahs in the wild. Because of their nomadic nature and vast territories, studying cheetahs in situ has always been a difficult task, and a large portion of what we now know about the species—their health, fertility, endocrinology, genetics—came from research done on captive cats.
But there are conservationists who question whether this strategy does much to help the wild population. With just an estimated 10,000 cheetahs remaining in the wild and everything from habitat destruction, to conflicts with farmers and the exotic pet trade threatening the species's survival, is this strategy the most effective way to protect these cats? What good is a friendly cheetah in Virginia to the ones facing extinction in the wild?
SCBI is situated on 3,200 acres of sprawling woodland in Virginia's Shenandoah mountains. The property was once home to a US Army cavalry remount station; horse graves still top the hillsides. Some of the 301 animals here—from red pandas to white-naped cranes—will eventually find their way to the Smithsonian's National Zoo in Washington, or other zoos in the US, but the breeding facility itself is not open to the public. Its prime focus is on research and the conservation of species endangered in the wild. Every animal there is either endangered or, like the Przewalski's horse, extinct in its natural habitat.
Though SCBI has been active since the 1970s, the cheetah breeding program is a relatively new addition—one of many passion projects for Dave Wildt, a biologist who has been studying cheetahs for more than 30 years and currently serves as SCBI's head of the species survival programs. Wildt spent the early part of his career studying cheetahs, both captive and wild, across sub-saharan Africa.
"We went out and had all these great experiences running around the Serengeti catching wild cheetahs and collecting sperm and blood samples for genetic studies," Wildt recalled as we sat in his office at SCBI, the walls dotted with photos of Wildt cradling fuzzy-headed cubs.
During his time in Africa, Wildt and his colleagues made some landmark discoveries about the species, like the fact that cheetahs had historically suffered multiple population bottlenecks, leading to a lack of genetic diversity. It also highlighted how little we knew about cheetahs, which helped explain why so many zoos and research groups had struggled to breed them in captivity. For decades, zoos in North America relied on importing captive-bred cheetahs from countries like South Africa, in part because they couldn't figure out how to breed them adequately. Wildt recognized the potential benefits of researching captive animals and wanted to open a dedicated cheetah center stateside.
"As long as I could remember, people had said this facility would be great for a cheetah breeding center but we had no money to build it," Wildt told me.
In 2004, talks about a cheetah program finally started to firm up. An anonymous private donor provided enough seed money to begin construction, and by 2007 the first two cats moved in. Unfortunately, because captive cheetahs were still so difficult to come by, they were both female.
"So much for a breeding program," Wildt said.
From the beginning, the center has been helmed by Crosier, who was fresh from a three-year stint studying wild cheetahs in Namibia. With only two females, she and her team spent those early years collecting a lot of data and studying the cats. They finally got a group of males in 2009, and saw their first births by the end of 2010.
The program was designed to benefit conservation in the wild, but it also had more immediate goals. SCBI wanted to created a well-oiled, self-sustaining cheetah-making machine to ensure there was always a supply of cheetahs for zoos in North America without depending on imports from Africa. Crosier said they've done data modelling that showed if they didn't produce 35 cubs total each year across North America, there'd be no captive cheetahs left on the continent within 100 years. They had to learn how to breed cheetahs effectively and consistently.
But they were facing a chicken-and-egg dilemma: they needed to breed cheetahs to understand more about the species, but no one really knew how to consistently breed cheetahs because of how little we understood them.
The only species in the genus Acinonyx, cheetahs are unique from other big cats in almost every way, from their behavior, to their social system, to their biology. This distinction goes far beyond not roaring, and it's what makes cheetahs so difficult to breed.
"There's no end to the challenges that we have with cheetahs," Crosier said, sighing. "You name it."
Like domestic cats, cheetahs are induced ovulators: they don't ovulate until after they've mated. When the female's eggs and follicles have matured enough that they're ready to be released, a buildup of hormones signals to the body that now is a good time to mate. This is called estrus, or being in heat.
If you've ever seen a house cat in heat, you know there are pretty obvious signs it's raring to go: it will call out, arch its back, roll on the ground. They're not exactly subtle. But one of the biggest hurdles in cheetah breeding is the fact that the females typically don't show any behavioral signs at all to signal when they're in heat. Testing isn't refined enough yet to detect estrus hormones in the cat's urine and feces either, and since their reproductive systems don't follow a regular cycle the way most mammals do, it's impossible to predict when a female is ready to mate.
To get around this issue, researchers have enlisted the only other creatures that care as much about a female cheetah's estrus cycle as they do: male cheetahs.
"We rely on our males a lot to literally tell us when the females are ready," Crosier said.
To test if a female is in estrus, they'll remove her from her yard temporarily and bring in a male. After smelling around the yard, if the female is in heat, the male will give out a distinct vocalization—a bark—trying to call her back to him. That's the sign she's ready to mate.
But the cheetah's ambiguous fertility cycle is only the first barrier of many. To keep a genetically diverse population in North American zoos, captive cheetahs are paired based on their DNA. This would work great if the cats mated with any other cheetah you bring into their yard, but of course it's not that simple. Sometimes the female refuses to mate, or shows aggression toward the male. Sometimes the males don't like the females and lash out at them.
It all goes back to the cheetah's unique social structure. Mature females prefer to be on their own, carving out a fairly large territory where they live and hunt solo. Males, on the other hand, tend to live in groups or two or more, called coalitions. These are usually brothers, bonded at birth and living together for their whole lives. But the average litter size is three cubs, so occasionally lone males (male cheetahs born with sisters who kicked them to the curb once they matured) will find each other later in life and team up.
"They seem to really need or want that male bonding," Crosier said. "It's very rare and very odd in a lot of ways."
Because of this unique structure, cheetahs are very sensitive to which other cheetahs they roll with or allow in their space. Housing the cats at a facility like SCBI can be a balancing act—neighbors sometimes don't get along and snarl at one another through the fences—and finding a love connection is trickier still.
To protect both animals, first meetings for potential breeding pairs are always done with a fence in between, Crosier said. If they like each other, a more intimate rendezvous is arranged, but even then, as with humans, sometimes it just doesn't happen. Still, researchers have optimistically dubbed the path dividing the male and female enclosures at SCBI "lovers' lane."
It hasn't been an easy road, but over the last seven years the team at SCBI has refined its breeding process, and learned a lot about the species along the way. They've had nine successful litters, and fine-tuned a process for getting females to foster abandoned cubs. (Mother cheetahs often neglect solo cubs because they can't produce enough milk to care for them, Crosier said.) While part of the goal is to create a self-sustaining captive population to keep cheetahs on exhibition at zoos in North America, Crosier said their biggest ambition is to better understand the species so they can do more to preserve it in the wild.
"A lot of our funding goes back into supporting research to study the cheetah home ranges and figure out where the cats are living to improve ways to mitigate conflict so not as many farmers are trapping the cats and there's not as many cats being shot," Crosier said. "The more you know about a species, the better you're able to manage them either in facilities in North America or in the wild."
SCBI's work has led to better understanding of the species and improved breeding techniques, which they believe can only serve to benefit conservation efforts. But there are conservationists who argue this approach is coming at the problem backwards, and that a cheetah in a cage is ultimately doing the species harm.
"You can breed cheetahs and keep them in captivity but that doesn't have a positive conservation value," said Adam Roberts, the CEO of Born Free USA, an animal welfare group that prioritizes protecting wildlife in their natural habitat. "There's no correlation between that and protection in the wild."
Roberts told me cheetahs in the wild are under great threat, and that hasn't changed in recent years as captive breeding techniques improved. Cheetahs are listed as vulnerable under the International Union for Conservation of Nature Red List, endangered under the US Endangered Species Act, and listed in Appendix I under the Convention on International Trade in Endangered Species—the section for species considered by the treaty to be most endangered.
Roberts told me the biggest threat right now is the capture of wild cheetahs as exotic pets.
Around the world, but in particular the Middle East, pet cheetahs have become a status symbol and getting your hands on exotic pets in some areas is "as easy as acquiring a cupcake." With Instagram making it convenient to flaunt cheetahs-as-accessories, the market for big cats is growing, Roberts said. He argued that not only do captive breeding programs not contribute much to the solution, they may also be part of the problem.
"Captive breeding masks the trade," Roberts said. "You have people in places like South Africa who are breeding cheetahs and supplying the international trade for zoos. That creates a laundering opportunity where these captive cheetahs are finding their way into trade, but so are the poached animals from the wild in the horn of Africa. As long as you have an international trade, you're going to have a negative conservation result."
One of the biggest reasons the SCBI started its breeding facility was so it could help create a self-sufficient captive cheetah population in North America so cats no longer have to be imported, but we're not quite there yet. Roberts questioned whether they should be devoting resources to breeding cats while the wild cheetah population continues to be whittled away.
"If you're going to study cheetahs, you should be studying them in situ," Roberts said. "Study them in the wild, where they belong."
There are lots of different approaches to conservation, but it's hard to deny the results from on-the-ground efforts as opposed to the more amorphous benefit of understanding the species better through captive study.
In Namibia, where Crosier worked for years for both the Smithsonian and the Cheetah Conservation Fund, conservationists have seen success by addressing some of the threats head on. Farmers in Namibia often kill cheetahs in an effort to protect their livestock. This greatly depleted the cheetah population in the country until groups like CCF started to seek out solutions. They've taught farmers about predator-friendly farming techniques, like trapping the cheetahs and calling CCF to relocate them instead of shooting them. They've also provided free guard dogs to farmers to help keep cheetahs at bay. These techniques were developed not through studying the genetics of the cheetah, but by investigating the root of the problem in the area and seeking out effective solutions, something Roberts argues is a more efficient use of resources.
Still, it's hard to discount the work SCBI is doing. It's not the same boots-on-the-ground efforts as CCF in Namibia, but it's one of many attempts working to conserve this species. Conservation efforts don't have to be only in situ or only ex situ, there's room for multiple tactics. And when you're facing a situation as dire as the preservation of one of the most unique species on Earth, we need all hands on deck.
Conservation is a field rife with contention. We don't always know what the best steps are, and when facing stakes like the obliteration of an entire species from the face of the Earth, tensions can run high. The strategy SCBI is taking is one with some obvious benefits, not the least of which being that, should we fail to protect cheetahs in the wild, these captive cats may be the only ones of their species left on the planet. If we don't know how to make more, the species is doomed.
But there are no easy, obvious solutions to the problem, which is why researchers like Crosier and Wildt keep chipping away. SCBI recently created a network with the seven other cheetah breeding centers in North America to share data and strategies. They meet once a month. Crosier is also hopeful they'll soon be able to produce a litter from in vitro fertilization, a first for the species. They're making progress.
It is a strange experience to see these creatures in captivity outside of a zoo. Without the flashy, faux-Serengeti backdrop around them, their enclosures—just a chain-link fence and some grass—reminded me more of a dog pen than a cheetah habitat. But I could also see the affection the whole team had for these animals. They can look at a photo and tell you the cheetah's name and birthdate. They know who each cat gets along with and who they can't stand. They know when Ashaki's brother died, and for how many days he stopped eating afterwards.
And the cheetahs? To me, they seem at the very least content. It may not be the Serengeti, but they're active. They're healthy. They're purring.