Is the Carnivore Preservation Trust creating a genetic future for threatened species—or genetic junk?
Originally published in Discover.
LORI WIDENER OPENS THE GATE of the 12-foot-high fence that surrounds the Carnivore Preservation Trust outside Pittsboro, North Carolina, and walks toward the home of her favorite resident, Scooter. “Where’s my boy?” she coos, peering into an enormous walk-in cage that holds two binturongs—Asian bear cats. Slowly, a whiskery black head with blond tipping pops out of a wooden den, and Scooter’s pupils contract as they adjust to the brightness. When Widener slips inside the cage, Scooter nuzzles her to mark her with his scent. Then he climbs her body and hangs from her neck by his muscular prehensile tail.
Four years ago, when they were 2 weeks old, Scooter and his littermates were taken from their mother and given to Widener to hand raise in her trailer just outside the 35-acre compound’s fence. Four times a day, she bottle-fed the animals a specially prepared formula of milk substitute, vitamins, and bananas. Most of the cats stayed two months, but the anemic Scooter required a blood transfusion from his mother and ended up recuperating inside the mobile home for an additional four months. During that time he developed a laid-back personality that made him very easy for his keeper to handle. “He is not tame,” insists Widener, an energetic 38-year-old who wears her hair in three waist-length braids. “He is not domesticated. He is merely socialized.”
Scooter certainly lives more comfortably than his wild cousins do in the rain forests of southeast Asia. Binturongs, a threatened species of tree-dwelling civet cats, are hunted for their meat. Males are also slaughtered for their genitalia, which are used as an aphrodisiac. At the same time, land development is shrinking their natural habitat. Yet binturongs, which don’t have the mass appeal of, say, elephants or tigers, have not been the focus of massive conservation efforts. Most American zoos, if they have any binturongs at all, have two or three. So the Carnivore Preservation Trust stepped in and now has the largest captive population in the world, as well as sizable populations of a handful of other threatened species of small wildcats. At last count, the nonprofit organization had 50 binturongs, 50 caracals, 39 servals, and 33 ocelots. The goal is to maintain large numbers of a few overlooked species, says the trust’s executive director, Margaret Tunstall. “Then, when somebody realistically tries to protect these animals and their habitats, we will breed a generation of animals that can be reintroduced into the wild.”
Laudable as that mission sounds, not every wildlife conservationist has embraced it. That’s because the Carnivore Preservation Trust has upended scientific orthodoxy, defiantly dissenting from the principles and methods used by most zoos to raise and breed animals in captivity. While mainstream animal conservationists adhere to the doctrine of having mothers raise their own litters, the trust follows a policy of raising young carnivores by human hand. And while most scientists believe in keeping subspecies lines as pure as possible, the trust intentionally disregards those lines, creating “generic” animals not found in nature.
“You’re not going to hear me say, ‘Hey, these people don’t have a clue,'” says Dave Wildt, head of the department of reproductive services at the National Zoo’s Conservation and Research Center in Front Royal, Virginia. “They know about science, and they are amazing about putting resources into housing large numbers of animals. Their animals are healthy and in great shape.” But by refusing to fully coordinate their breeding efforts with the greater zoo community, he says, the trust is creating “genetic junk”—hybrid animals whose descendants can never be reintroduced into the wild. He is blunt: “These people are not contributing to conservation.”
THE CARNIVORE PRESERVATION TRUST GREW out of the personal passion of the late Michael Bleyman, a gray-bearded geneticist who left his University of North Carolina faculty job in 1975 to follow his real love: studying tigers, jaguars, and other large felines whose survival was threatened in the wild. His interests were only partly academic. “Mike was a scientist who had a strong interest in wildcats, and he wanted to save those cats,” recalls Wildt. “But he also liked the excitement of having a 500-pound Siberian tiger in his backyard.”
From the time he got his first felines, Bleyman tried to learn everything he could about taking care of them. He knew that some large cats had trouble breeding in captivity, and he wondered if different husbandry practices, including a more natural diet and more secluded environs, could improve the animals’ reproductive success. In his quest for information, he traveled the world and began to grasp the broader connections between animals and their habitats. “He saw that in order to do good, you have to have a full-out effort to save the environment as well as the animals,” says his daughter, Anne Bleyman. “There has to be land set aside that people would not develop. At the same time, he thought if he could start breeding these species, and do it in such a way that there would be an outbred, genetically sustainable population in captivity, then down the line people might start setting aside land.”
The trust formally began in 1981, on the farm where Bleyman was living. Lacking money, he rallied an enthusiastic platoon of volunteers, drawn by the organization’s mission and Bleyman’s own charisma. By all accounts, even the cats responded to his powerful personality. “All the tigers thought he was God,” says Widener, the trust’s development director. She remembers being in a cage with Bleyman, who was only about 5 feet 7 inches tall, and looking on with awe as he tried to separate two angry cats. “This tiger had its ears back, snarling, growling,” she recalls. “And Michael was standing there, three feet away, his hands on his hips, yelling back, ‘You want a piece of me? Come on!'”
Over time, Bleyman decided he was breeding the wrong animals. He couldn’t possibly keep enough tigers, leopards, and jaguars on his parcel of land to make a difference in the species’ survival. Instead, he switched his focus to animals he could house in large numbers. The trust never got rid of its big felines, but it stopped breeding them and concentrated instead on smaller carnivores. In addition to binturongs, Bleyman selected caracals, lightning-fast hunters from Asia and Africa with long, tufted black ears and powerful jaw muscles. Capable of taking down large animals such as gazelle—and of jumping into the air to knock down birds with their front paws—caracals are considered pests by farmers. Ocelots were another choice. Coveted for their lush pelts, they were hunted nearly to extinction during the 1960s and 1970s and remain rare throughout the Americas. Bleyman completed the small-cat menagerie with long-necked servals. Natives of Africa, servals are also hunted for their fur, which can be passed off as cheetah or leopard, and their habitat is shrinking from human encroachment. Bleyman described his efforts as “an insurance policy.” The mission of the Carnivore Preservation Trust, he said, “is to provide a living time capsule, holding these animals in trust for the world until the world is able to protect them.”
Even as he amassed disciples, however, Bleyman clashed with animal conservationists. “He fell out with people with whom he should have used words of honey rather than vinegar,” says Trudy Raumann, a retired physicist who has volunteered at the trust for the past 10 years. “Like so many geniuses, he wasn’t so easy to be with all the time.”
But it was his scientific principles that really irked the conservation community. Bleyman believed that too much value is placed on keeping subspecies breeding pure. “Generic animals are virtually useless for reintroduction purposes,” says Michael Hutchins, director of conservation and science for the American Zoo and Aquarium Association. The reason? “We don’t know whether subspecies are important ecotypes—how closely adaptive they are to a certain environment. If you don’t know, it’s better to maintain the differences.”
Bleyman maintained that endangered subspecies’ genetic pools were often too small to propagate healthy offspring indefinitely. In his view, the only hope of survival for tigers and some other wildcats was to breed across subspecies lines—to purposefully create specimens that would be more genetically diverse than their parents. “He was very unpopular with the zoo community for this,” says Widener. “They called them ‘mutt tigers’—American generic tigers.” When animal-conservation organizations established breeding protocols for certain animals, Bleyman ignored them.
So how important is it to keep a subspecies pure? And what defines a subspecies, anyway? Nineteenth-century mammalogists “named populations with little more criteria than a hide or skeleton from a particular geographic locale,” says Stephen O’Brien, who heads the genomic diversity laboratory at the National Cancer Institute. Nowadays, however, researchers are distinguishing animal groups by their DNA. Some subspecies, it turns out, are distinctly different from one another, while others are almost identical. “They’re closer, in many cases, than human ethnic groups, and nobody argues that we should keep the ethnic groups separate, at least not anymore,” says O’Brien.
One example of how dicey divisioning has been is the traditional sectioning of leopards into 27 subspecies. Scientists studying the DNA of 14 of these groups have found justification for only eight of the partitions. In particular, the African subspecies of leopards are almost indistinguishable. “There’s no obvious line at which you say these are different subspecies,” says Jonathan Ballou, population manager at the National Zoo. “So far, though, there isn’t a consensus.”
Indeed, wildlife conservationists tend to fall into two camps: lumpers, who aggregate similar animals, and splitters, who keep them more strictly separate. Splitters, who dominate the mainstream conservation community, have decided on occasion to lump. The most famous case of the last decade involves the Florida panther, a type of cougar whose population dwindled to a few dozen because of hunting and habitat invasion. With such small numbers, the cats were dangerously inbred—more prone to infectious disease, low sperm production, and life-threatening heart defects. After considerable debate, scientists agreed to introduce Texas cougars into the Florida cats’ habitat. Preliminary field reports indicate the project has been a success. About a fifth of the 36 kittens born since the program’s 1995 start are the offspring of Florida-Texas pairings. “Is it admirable to mix them naturally? Sometimes,” says geneticist O’Brien, who collaborated on the project. “That Florida population was doomed otherwise.”
More often, scientists prefer to err in the other direction. “We take a conservative approach: When in doubt, don’t breed them,” says Jill Mellen, a research biologist at Disney’s Animal Kingdom in Orlando, Florida. For instance, the American Zoo and Aquarium Association has asked members not to crossbreed ocelot subspecies. Instead, the association is focusing on propagating a particular Brazilian ocelot. There will be a scant 18 in captivity in North America—if several can be imported from their native continent. At the trust, things will go predictably in the opposite direction: Members are convinced the zoo community will not get enough specimens for successful outbreeding and therefore plan to continue breeding their own generic ocelots.
“In an ideal world with large and healthy captive populations of all extant subspecies and an infinite number of zoos and wild animal parks in which to breed these subspecies, it might be prudent practice to maintain these populations as genetic breeding isolates,” Bleyman wrote. But, he added, the animal conservation community needs to “face reality” and aim to preserve species rather than subspecies. “If we look, for example, at the registry of all ocelots in captive breeding, we see a rather pathetic scattering of subspecies spread out throughout the world’s breeding institutions. Many subspecies are represented by only one or two individuals in captivity in the whole world. The entire weight of practical experience suggests that these fragments of breeding populations cannot be maintained with any success at all.”
Who’s right? Based on the available science, there’s no clear answer. The National Zoo’s Ballou, who is not involved in the ocelot project, says 18 founding animals might be sufficient to maintain 90 percent of the gene pool for 100 years, but only if the descendant population can eventually grow to 400 or more. “We usually think of 25 or 30 [founding] animals as necessary,” he adds. With fewer, “it wouldn’t take much time to run into all sorts of problems. In that case, some people might argue to combine them.”
MICHAEL BLEYMAN ALWAYS EXPECTED to die young, and his loved ones didn’t doubt him. “I always assumed he’d be off in some other country, tick somebody off, and get killed there,” says his daughter, Anne. Still, it came as a surprise when he was diagnosed in 1996 with kidney cancer, which killed him within three months. He was 58.
For a couple of years after Bleyman’s death, the organization foundered. The Carnivore Preservation Trust was so much Bleyman’s personal project that he had never laid the groundwork for anyone to succeed him. At one point, the compound was down to one keeper, who was stretched to the limit trying to care for more than 200 animals. But during the past two years, the trust has been professionalized, hiring its first staff veterinarians, boosting the number of keepers, and working to strengthen its ties with other conservationists. It even participates in American Zoo and Aquarium Association meetings. One result: Following the recommendation of a zoo official, the trust is paring its populations, keeping only the most diverse breeding stock.
At the same time, the trust has sharpened its research mission, inviting scientists to come to North Carolina to work with its large samples of understudied animals. “If you think that research on how things vary among carnivores is important, then the trust provides a real resource,” says Bill Peake, a professor of electrical and bioengineering at the Massachusetts Institute of Technology. Peake has traveled to Pittsboro to examine the ears of the trust’s large and small cats as part of a study of feline acoustic sensitivity. His findings indicate that the middle ears of large tigers and jaguars are structured to respond better to the low frequency sounds emitted by the large prey they favor, like buffalo. In contrast, the middle ears of smaller caracals, servals, and ocelots are more sensitive to the high frequencies of mice and the other small animals they hunt.
Still, even with its forays into the mainstream community, the Carnivore Preservation Trust hasn’t lost its reputation as a renegade operation. Five years after Bleyman’s death, the organization clings closely to his heretical principles—and not just in its generic breeding program. Bleyman believed strongly in hand rearing young animals. Every animal born at the compound is separated from its mother after two or three weeks of receiving the protein—and antibody-rich colostrum, or first mother’s milk. Then each animal is raised by the trust’s keepers in their homes and in the farmhouse’s nursery. Eureka and J. Edgar, two 4-week-old servals, received typical treatment. They slept in a blanket-lined playpen next to an electric heating pad set on low to mimic the heat their mother would generate, sucked low-lactose infant formula from handheld bottles, and were burped.
Caretakers at the trust say such care not only makes animals more manageable, it reduces their stress around humans, making them more reproductive. The trust doesn’t have statistics to measure that success, but it evidently has no problem getting animals to mate. Recently, the compound crawled with 22 babies, all simultaneously hand reared. “Here, breeding is very natural,” says Allison Larios, who until last month served as the trust’s head curator. “In fact, we can’t get them to quit.” She agrees that hand-raised animals aren’t candidates for reintroduction into the wild, but she maintains that the trust is no more than three generations away from producing animals that can fend for themselves.
Zoos vehemently oppose hand rearing, trying instead to keep young mammals with their mothers for as long as possible. “It’s well documented that hand raising has long-term behavioral effects,” says Hutchins of the American Zoo and Aquarium Association. “Animals become socially attached to human caretakers, and later on in life can develop a sociosexual attachment to the species that hand raised them. In a popular sense, you can say they are confused about their species identity. This can have a long-term effect on breeding.” The most oft-cited study, conducted by biologist Mellen, indicated that maternally reared domestic cats were more likely to breed than cats separated from their littermates and raised by humans. Cats hand reared with their siblings—like the animals at the trust—fell somewhere in the middle. But Mellen notes that her findings are not conclusive: The results for the hand-reared sibling group were not statistically significant compared to the other two groups.
Even so, as long as the trust continues separating babies from their mothers, it will not be a welcome player in mainstream efforts to conserve the species it wants to save. That is a consequence the trust is willing to accept. “If mortality rates are going to increase when babies are left with their mothers, I’d just as soon hand raise them,” Larios says.
The Carnivore Preservation Trust is willing to ruffle still more feathers by following Bleyman’s breeding agenda. The American Zoo and Aquarium Association wants to reduce the world’s captive caracal population from 250 to 75, noting that their numbers remain healthy in the wild. “Caracals are not an endangered species,” says Alan Shoemaker, collection manager at the Riverbanks Zoological Park in Columbia, South Carolina. “They have huge ranges. They are never going to become extinct in your lifetime or mine.”
Nonetheless, the trust, which owns about a fifth of all captive caracals, says it has no plans to stop breeding them. Larios points to an earlier lesson. “When we started working with ocelots and binturongs, they weren’t endangered either,” she says. “If we don’t take strides to preserve the caracals here, then what will happen when those numbers drop off in the wild? It’s only a matter of time.”