On a recent November afternoon, a white-naped crane named Walnut squawks loudly, then juts her long neck back and forth, mimicking the movement of an animal keeper nearby.
The hand-raised crane has come a long way since she arrived at the Smithsonian Conservation Biology Institute (SCBI) in 2004. Then 24 years old, she had never been able to breed due to her close relationship with people. In fact, when she tried to breed naturally at other facilities, she killed two male cranes in the process.
But SCBI staff have been able to use artificial insemination to help Walnut produce six chicks since she arrived.
Walnut is just one success story of the institute, a 3,200-acre (1,290-hectare) campus among the rolling hills and hayfields of Front Royal, Virginia (map).
As a home for the nearly extinct, SCBI welcomes endangered animals from all over the world so their species might be saved. Twenty-one species of birds and mammals live on campus. (Related: "Pictures of Nearly Extinct Species.")
The institute leads conservation efforts for the National Zoo in Washington, D.C., and other sites around the world. Its Center for Species Survival focuses on studying and breeding rare species and, in some cases, supporting efforts to reintroduce them back into the wild.
Although SCBI has been doing this work for nearly four decades, it's needed now more than ever, experts say.
"Every day we are seeing the loss of species and the habitat these plants and animals are dependent on for their survival," says Paul Marinari, the institute's senior curator of animal operations.
Stuart Pimm, president of the group SavingSpecies and a conservation ecologist at Duke University in Durham, North Carolina, says that places like SCBI are truly the last hope for some species.
"The first thing we should be doing is protecting species in the wild, in their habitats. But the reality is, for some species, the only thing we can do is to keep it in captivity. And then, with luck and with time and with opportunity, we can put them back in the wild," says Pimm, who has no affiliation with the center.
"This is a difficult, last-ditch effort to save species, but sometimes we don't have any other alternatives."
For the Birds
Before these grounds were a refuge for rare species, they served as a U.S. Army remount depot.
Driving around the campus, Marinari pointed out an old stallion barn where the military readied horses and mules for war efforts during the first half of the last century. He says that the area was later used as a detention facility for hundreds of German and Italian prisoners of war. The stone walls they built are still scattered around the campus today.
Along a winding road not far from one of these walls live groups of hooded, red-crowned, and white-naped cranes—one of the largest crane collections in North America. Among the most endangered bird species in the world, cranes are threatened by habitat loss.
Zoos from all over the continent send their most difficult cranes—those with behavioral and physical problems, many of whom have never been able to breed—here. Because the cranes have never reproduced, often they are the most genetically valuable of their species.
Watch a video of SCBI's white-naped cranes making unison calls.
"You want to make sure that every single individual passes on its genetic material," Marinari says. (Learn more about the role zoos play in conservation.)
Another rare bird species, the mammal-like New Zealand brown kiwi, lives in a series of burrows that weave in and out of a nearby building. Warren Lynch, a supervisory biologist who began his career at SCBI as a volunteer 20 years ago, helped coax one of the nocturnal animals out of its burrow, but the unhappy bird quickly moved underground to go back to sleep.
Watch a video about the North Island brown kiwi.
Not yet considered endangered, the brown kiwi population is estimated to be less than 25,000, a stark difference from the millions that once existed.
Since little is known about the flightless birds, biologists here are studying their reproductive cycles to determine whether they are seasonal breeders.
Once a species becomes extinct in the wild, Marinari says, the lack of genetic diversity among animals that remain makes it difficult to do research.
"The time when you want to do basic science is when you don't only have a few left," he says. (Watch video: "Should We Resurrect Extinct Species?")
But funding for this work is an ongoing struggle. In 2001, the center was threatened with being shut down, and budget cuts in more recent years have led to a lack of resources.
Last week, the death of a young Przewalski's horse at SCBI—which followed the deaths of an antelope, gazelle, and red river hog earlier this year at the National Zoo—sparked concerns about the welfare of Smithsonian's animals. (Related: "National Zoo Deaths: 'Circle of Life' or Animal Care Concerns?")
Dennis Kelly, director of the National Zoo, told the Washington Post that budget uncertainties and a thinly stretched staff may have contributed to the incidents. "We take every concern seriously and have protocols and processes in place to evaluate and update our management techniques," the zoo said in a statement.
SCBI's bird collection started in 1975. Nine years later, two endangered Micronesian kingfishers were brought here after their population dropped to just a few dozen animals due to predation by the invasive brown tree snake. (Related: "Heads Up to Invasive Pests: Poison Mice Falling From the Sky.)
In the two decades afterward, the worldwide kingfisher population stayed under 60—all in captivity—but now, thanks to breeding efforts, the population is steadily increasing.
Watch a video of kingfishers at the Smithsonian institute.
Today there are an estimated 124 Micronesian kingfishers alive, five of which live at the Front Royal facility. If the trend continues, scientists may begin to reintroduce the species back into the wild.
But if a species has gone extinct in the wild once, what's to keep it from going extinct again? "Circumstances can change," says Pimm, who is also a contributor to National Geographic's News Watch blog.
For instance, in the case of the kingfisher, its habitat may be a bit less threatened now than in the 1970s: The U.S. government is killing many of the invasive snakes by air-dropping dead mice stuffed with Tylenol, which is toxic to the reptiles.
"In the case of some animals, better protection [of their habitat] gives those animals a chance to make it back."
Hope for the Oryx
One of those animals may be the scimitar-horned oryx of northern Africa. Declared extinct in the wild in 2000 by the International Union for Conservation of Nature, there are fewer than 2,000 of these antelopes in the world, most of which live in captivity, according to Budhan Pukazhenthi, a reproductive physiologist at SCBI.
But ongoing research may make it possible for this species to eventually return to and thrive in its native lands.
For instance, SCBI was among the first to successfully breed scimitar-horned oryx via artificial insemination, and its scientists are beginning to experiment with how to mate the large mammal naturally. (Related: "First Przewalski's Horse Born Via Artificial Insemination.")
SCBI is also launching a new initiative in conjunction with Conservation Centers for Species Survival—a group of five centers that collectively manage more than 25,000 acres (10,000 hectares) dedicated to endangered species—called the big-herd scenario.
"We are trying to look at the pros and cons of breeding these animals in small groups, one on one, versus having a large herd system, which is natural to their social behavior," says Pukazhenthi. He expects that breeding in the herd will produce more oryx with better social skills at lowered costs.
The big unknown is understanding the genetics of individual oryx. "We really don't know the true [bloodlines] of some of these animals," Pukazhenthi explains. "We are launching a process where we can identify every individual in the population and we can then go back and reunite their pedigree, which will allow us to better manage the population for the future."
Into the Wild
SCBI also recently entered a partnership to help reintroduce the scimitar-horned oryx back into Chad.
"We are talking about hundreds of animals being reintroduced in a short window," Pukazhenthi says.
The greater the number of animals reintroduced, the more likely they are to thrive, but drought, hunting, and competition from livestock could still threaten reintroduced oryx populations.
What's more, even for species considered successes, there can be setbacks, notes Marinari. For instance, some of the endangered black-footed ferrets raised at the institute and reintroduced back to their western U.S. habitats have been hit with disease.
"We meet these challenges head-on," he says, by adapting to the situation as it happens and learning as much as possible about the species and its threats.
Despite the risks, conservationists say trying to save rare species is a battle worth fighting.
"It's a profoundly ethical issue," says Duke's Pimm.
"Are we going to hand to our grandchildren a world that is much poorer in species than the one we inherited from our grandparents?"
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Want to continue the conversation? Ask conservationist Quentin Wheeler, @DeanWheeler, about how to save Earth's rare species during a Twitter chat on Friday, December 20, at 11:30 a.m. ET. Follow Quentin and use #NatGeoLive to tweet questions.