The first release of young black-footed ferrets into the wild was a disaster. It was 1991 and scientists had released 49 animals in Shirley Basin, north of Medicine Bow, Wyo. Nearly every one died in the first year, mostly in the jaws of coyotes and badgers.
The animals had been raised in captivity. Their species, Mustela nigripes, had at one point been thought extinct. But after a small population was rediscovered in 1981, scientists captured the remaining 18 animals. The goal was to breed the ferrets and then reintroduce their species back into the wild.
But it wasn’t as easy as just letting young ferrets loose, the scientists quickly learned. Having grown up in a sheltered environment, the animals didn’t know how to hunt. They also didn’t know how to avoid predators.
And they paid the price.
Now, before any are released into the wild, black-footed ferrets must go to “boot camp.” It’s an intensive period of training when they learn how to fend for themselves. The hardest part for most of them is recognizing — and escaping from — those animals that want to make a meal out of them. But the program has been a success. As of 2017, some 350 black-footed ferrets could be found roaming North America, largely in Wyoming, South Dakota, Montana, Arizona, Colorado and Kansas.
Black-footed ferrets are now a poster child for something called “rewilding.” This is the careful and planned reintroduction of animals to an environment from which they had disappeared.
Scientists have been working to rewild many animals around the globe. That’s because wild animal species are quickly disappearing in many parts of the world. Humans are destroying the places where they live. We are doing this by building cities, logging forests, mining rocks and taking oil and gas out of the ground. Sometimes people hunt too many animals for their populations to recover.
All of this puts more and more animals are at risk of extinction. To save them, some of these animals are being bred and raised in captivity. Examples include the eastern quoll (an Australian marsupial) and the scimitar-horned oryx (a type of African antelope).
For many species, though, there is a problem: If the animals are to survive long enough to have babies, they must be fed and protected from predators. But such protection stops the young ones from learning how to hunt for their own food and find shelter.
And here’s where scientists are stepping in to help.
Robo-badger and a stuffed owl
Thirty-seven years ago, a Wyoming rancher's dog carried home a strange-looking animal carcass. The slim, cream-and-black creature was about the size of a house cat. Its feet, face and tail tip were black. The rancher didn’t recognize it. Intrigued, his wife asked some wildlife biologists if they could identify the animal. And to their shock, the could. It was a black-footed ferret — a creature they had assumed was extinct.
These members of the weasel family are the only ferret native to North America. Ferrets mostly eat prairie dogs and use their burrows for shelter. But early in the last century, as people turned prairie into farmland, many populations of prairie dogs disappeared. Those animals now occupy less than 2 percent of their original habitat.
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The rancher's property had enough prairie dogs to support a small population of black-footed ferrets. But six years after their discovery, the ferrets got sick with a serious disease. Just 18 survived. Government biologists raced to round up each one and place it in captivity. The goal was to one day release future generations of them back into the wild.
Since that first failed attempt at rewilding, all black-footed ferrets raised in captivity attend boot camp before release. This takes place at the U.S. Fish and Wildlife Service’s facility in Fort Collins, Colo. Wildlife biologist Dean Biggins of the U.S. Geological Survey developed the program for toughening up these creatures. He started by bringing in Siberian polecats from China.
Siberian polecats are the black-footed ferrets' closest relatives. Biggins figured they would respond to his training much as the ferrets would. There were so few ferrets that he didn’t want to risk testing boot-camp techniques on them, in case they failed.
Biggins and his fellow biologists raised the polecats in the same 1-by-1.2-meter (3-by-4-foot) cages in which the ferrets were reared. They then tested their reactions to pretend predators. This included something Biggins and his co-workers called “the robo-badger.”
It was a roadkill badger. The researchers mounted it onto the chassis of a toy truck, then had it chase the polecats around. “But robo-badger was slow," Biggins recalls. “And although he looked like a badger, he just didn't behave like one.”
So the researchers obtained a more convincing stuffed owl, also a ferret predator. Biggins tied the stuffed owl to a line so he could make it swoop down on the polecats.
When the first generation of polecats born in captivity saw the owl, they fled to their boxes. There they cowered for hours. But each new generation became less wary. By the fourth generation, the owl didn’t worry them at all.
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Re-scaring these potential prey
The results were no surprise. Biggins hoped his next experiment would show was that this unwary behavior was reversible. He wanted the polecats to fear those predators again.
To do this, he raised the third generation of polecats in larger, outdoor pens. These resembled the polecats’ natural environment. Biggins hoped this would help the babies relearn how to be wary and avoid animals that viewed them as lunch.
While it was a relatively normal habitat, the animals were still protected from predators. The animals had to live long enough to unlearn bad habits, of course. To Biggins’ relief, each new generation became more and more frightened of the owl. Eventually, their reactions were close to normal.
"Why that happened, we don't know," Biggins says. "Was it simply lack of human attention? Or being in burrows where mom can transmit escape behavior? Or are they more physically fit?"
Biggins’ team is now using the same technique with ferrets. He knows not every animal is ready for release. Still, he points out that it's too expensive to test each ferret. They are simply given the best possible training. The rest is up to them.
And he must be doing something right. Black-footed ferrets released today have survival rates 10 times better than those raised in the original small cages.
California condors look like something out of prehistory, because, in a way, they are. “They lived back 10,000 years ago with American mastodons and saber-toothed cats,” says Michael Mace. He is the director of animal collections and strategy at the San Diego Zoo Safari Park in California. “Of all the giants of that time,” he notes, “the condor is the only one to be with us today.”
The condors are a type of vulture, birds that scavenge dead animals as food. Their wing span is just over three meters (nearly 10 feet), making them the largest bird in North America. They have bald heads and black feathers with patches of white on the underside of their wings.
Though the birds outlived mastodons and saber-toothed tigers, they are in trouble now. Habitat destruction in the American West and Southwest, along with hunting, has dramatically reduced their numbers. Indeed, by the late 20th century they were nearly wiped off the face of the Earth. And the major reason: their vulture habits. Some of the carcasses the birds scavenged had been riddled with lead from bullets. That heavy metal is toxic. Over time, it sickened the condors — and they died.
By 1987, there were just 22 California condors left. Biologists rounded them up and took them to zoos in San Diego and Los Angeles, Calif. Protected and fed, these birds reproduced. By 1991, there were enough condors to start releasing them back into their ancestral homes — California, Arizona, Utah and Baha, Mexico.
But first, the condor chicks had to learn how to be wild. Like many birds, California condors form tight bonds — called imprinting — with their caregivers. They see these caregivers — whether condor or human — as a parent. They try to imitate them.
The zookeepers had to make sure the chicks didn’t look to a human as their parent. That wouldn’t be healthy for wild birds. To avoid this, the researchers used a leather hand puppet to feed and care for the chicks. That puppet looked like an adult condor. The staff stood behind a curtain, thrusting the puppet toward the chicks through a hole in the fabric. A recording of a babbling brook masked the sound of human footsteps and other unnatural noises.
Zookeepers learned how to care for chicks by watching videos of condor parents. Proper care requires more than just placing raw meat in the nest. Just like real condor parents, the puppets must poke at the meat, nudging it toward the chicks.
The puppet birds also play with the chicks and groom them. When a chick tries to bite a “parent” or strays too close to the edge of the nest, the puppets even discipline the chick. The puppet will hit the misbehaving offspring, though, of course, not hard enough to injure them.
But the chicks also need to see real adult condors. So zookeepers installed a big window in the chicks’ enclosure. It looks onto the aviary where the chicks can see captive adult condors flying by.
“We are always reinforcing to the chicks, ‘You are a condor, not a person,’” says Mace.
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Despite all of these precautions, the first condors released into the wild were kind of wild, but not in a good way. “It was like a school yard without a teacher monitoring them,” recalls Mace. “They would fly into people’s yards, tear up the cushions on their lawn chairs, drink out of their swimming pools and stand on their porches.”
But by the time those birds started having babies of their own, the condors had learned to stay out of trouble. And when it came time to release the next batch of condors from the zoo, they now had adult role models in the wild. Explains Mace, things went smoother after that.
Today, there are 275 California condors flying free in the American west and Mexico. Another 200 or so are in captivity, awaiting their turn to fly free.
While humans don’t make good condor parents without a disguise, no such camouflage is needed when working with young orangutans. Humans and orangutans are both primates. As such, we have much in common. And that has proven useful in the southeast Asian nation of Indonesia.
Some 55,000 orangutans live on the Indonesian island of Borneo, according to one estimate. On the neighboring island of Sumatra, there are another 14,000 or so. That may sound like a lot, but all the orangutans in the world could fit into one U.S. football stadium — with room to spare. Their numbers have been dwindling due to habitat destruction and hunting.
Today, roughly 1,200 orangutans live in rescue centers. Some of these tree-dwelling apes were brought to them from recently logged areas. Others came from private homes, where they had been kept illegally as pets. And still others came from circuses where they were made to perform — riding bicycles, or dancing.
“Many have lost their culture to some extent,” says Leif Cocks. “We try to replace it by showing them how to be orangutans.”
Cocks is a biologist and an expert in primate behavior. He runs a rescue center in the Indonesian jungle called the Orangutan Project. The center is in Sumatra near Bukit Tigapuluh National Park (which is also known as “30 Hills”). It is home to about 175 rescued orangutans.
Before their training can begin at 30 Hills, human caregivers check each animal for disease. They don’t want to run the risk of reintroducing an orangutan into the wild only to have it spread disease to others.
When it has a clean bill of health, the animal can meet its fellow orangs. Through trial and error, each slowly learns how to socialize with others. It also goes to “jungle school” from 9 a.m. to 3 p.m.
In jungle school, human caregivers carry the animal into a large enclosed space within the jungle. There, it can climb trees and swing on vines, building up its strength. The orangutan also learns an important skill: assessing which branches and vines are strong enough to take its weight.
If they don’t recognize specific fruits and plants that are good to eat, human caregivers will help the animals out. An orangutan at 30 Hills must be able to do two things before qualifying for release. First, it must identify 120 different food sources, including termite mounds. Second, it must be able to successfully build its own nest.
Cocks says the whole process of learning to be an orangutan takes an average of three years.
Even then, orangs go through what’s called a “soft release.” This means they have small radio trackers implanted in their shoulder blades. That lets caregivers monitor them and return to help animals that run into trouble. An orangutan’s soft release can also take up to three years.
Cocks estimates that more than 1,000 orangutans have been reintroduced into the jungles of Indonesia since the late 1960s. The problem now is that much of their habitat is gone. Unless we conserve and restore jungles, he says, there may be nowhere for them to go, no matter how much help people give them while growing up.
Such rewilding efforts are clearly costly and time-consuming. They also may be the only way to ensure that species on the brink of extinction — often due to human activities — get a second chance at survival.
ape A group of rather large “Old World” primates that lack a tail. They include the gorilla, chimpanzees, bonobos, orangutans and gibbons.
average (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.
badger Muscular, short-necked members of the weasel family found across several continents. Only one species lives in the Americas. Today, its dwindling and fairly solitary populations roam the arid western United States.
behavior The way something, often a person or other organism, acts towards others, or conducts itself.
biology The study of living things. The scientists who study them are known as biologists.
Borneo The largest island in Asia and third largest in the world. It is mountainous, covered by vast expanses of rainforest and sparsely populated by people. Part of its land belongs to the nation of Indonesia, a small part to the sultanate of Brunei and the rest to the nation of Malaysia.
breed (noun) Animals within the same species that are so genetically similar that they produce reliable and characteristic traits. German shepherds and dachshunds, for instance, are examples of dog breeds. (verb) To produce offspring through reproduction.
camouflage Hiding people or objects from an enemy by making them appear to be part of the natural surroundings. Animals can also use camouflage patterns on their skin, hide or fur to hide from predators.
chassis The frame of a vehicle that supports its working parts, including its wheels.
conserve To protect, as from loss or degradation.
coyote This relatively long-legged member of the dog family (Canis latrans) is sometimes referred to as the prairie wolf. It is, however, notably smaller and its build more scrawny than a true wolf. Found from Alaska down into Central America, coyotes have lately expanded their range into all 50 U.S. states. Many now hang out in urban areas where they have no predators and can easily dine on rodents and scavenge trashed food.
culture (n. in social science) The sum total of typical behaviors and social practices of a related group of people (such as a tribe or nation). Their culture includes their beliefs, values and the symbols that they accept and/or use. Culture is passed on from generation to generation through learning. Scientists once thought culture to be exclusive to humans. Now they recognize some other animals show signs of culture as well, including dolphins and primates.
curator Someone who manages a collection of items, for instance in a museum, library or art gallery. This person’s primary job is to design exhibits, organize and acquire collections and do research on the artifacts included in the collection.
environment The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of components in some electronics system or product).
extinction The permanent loss of a species, family or larger group of organisms.
ferret A mammal belonging to the family of animals that includes weasels, skunks, otters and badgers.
generation A group of individuals (in any species) born at about the same time or that are regarded as a single group. Your parents belong to one generation of your family, for example, and your grandparents to another. Similarly, you and everyone within a few years of your age across the planet are referred to as belonging to a particular generation of humans. The term also is sometimes extended to year classes of other animals or to types of inanimate objects (such as electronics or automobiles).
groom (in zoology) The practice of some animals to clean another, usually in places the groomed animal can’t see or reach, such as the back, head or face. Sometimes a groomer will remove ticks or other parasites. Other times it might remove tangles in fur or debris such as leaves. The attention the groomed animal receives can be calming and is usually accepted only from a family member or close member of its social group.
habitat The area or natural environment in which an animal or plant normally lives, such as a desert, coral reef or freshwater lake. A habitat can be home to thousands of different species.
imprint (in biology) A term for process by which a young animal comes to view some other animal (or person or thing) as its parent or trusted caregiver.
lead A toxic heavy metal (abbreviated as Pb) that in the body moves to where calcium wants to go (such as bones and teeth). The metal is particularly toxic to the brain. In a child’s developing brain, it can permanently impair IQ, even at relatively low levels.
monitor To test, sample or watch something, especially on a regular or ongoing basis.
native Associated with a particular location; native plants and animals have been found in a particular location since recorded history began. These species also tend to have developed within a region, occurring there naturally (not because they were planted or moved there by people). Most are particularly well adapted to their environment.
orangutan One of the great apes (which also include gorillas, chimpanzees and bonobos), this red-haired tree dweller shares 97 percent of its genes in common with humans. They can live for 60 years, with adults weighing 48 to 130 kilograms (105 to 286 pounds) depending on gender, age and health, with males being bigger. They have opposable thumbs (as humans do) and also opposable big toes, which aids in their gripping.
oryx The genus name for six species of large antelopes that are native to Africa and the Arabian peninsula. All have with horns (some straight, some curved), with the females sporting the longest horns. Their pale coats help reflect heat in the hot environments in which many live. They also may have dark markings, mostly on their faces.
population (in biology) A group of individuals from the same species that lives in the same area.
prairie A type of fairly flat and temperate North American ecosystem characterized by tall grasses, fertile soils and few trees.
prairie dog A social animal (Mustela nigripes) about the size of a large squirrel that lives in burrows that form large colonies — known as prairie-dog towns. Each “town” may extend across many hectares (acres). The animals have a bark-like call, short legs and sharp claws. They can live for up to 8 or 10 years.
predator (adjective: predatory) A creature that preys on other animals for most or all of its food.
primate The order of mammals that includes humans, apes, monkeys and related animals (such as tarsiers, the Daubentonia and other lemurs).
quoll A small, meat-eating marsupial that has a spotted coat and looks similar to a cat. These animals are native to Australia and New Guinea.
radio To send and receive radio waves, or the device that receives these transmissions.
rewilding (v. to rewild) The careful and planned reintroduction of animals to an environment from which they have disappeared.
risk The chance or mathematical likelihood that some bad thing might happen. For instance, exposure to radiation poses a risk of cancer. Or the hazard — or peril — itself. (For instance: Among cancer risks that the people faced were radiation and drinking water tainted with arsenic.)
saber-toothed cat Once popularly referred to as a saber-toothed tiger, this cat (Smilodon fatalis) is not closely related to tigers at all. Adults of this bobtailed species were about 30.5 centimeters (roughly one foot) shorter than today’s lions but would have weighed twice as much. Unlike lions and other big cats of Africa, the saber-toothed cat probably did not chase down its prey, but instead ambushed it from a hiding place. The species died out roughly 10,000 years ago.
scavenge To collect something useful from what had been discarded as waste or trash.
species A group of similar organisms capable of producing offspring that can survive and reproduce.
Sumatra A part of the island nation of Indonesia, this is one of its bigger islands (and indeed, the sixth largest island in the world).
termite An ant-like insect that lives in colonies, building nests underground, in trees or in human structures (like houses and apartment buildings). Most feed on wood.
toxic Poisonous or able to harm or kill cells, tissues or whole organisms. The measure of risk posed by such a poison is its toxicity.
transmit (n. transmission) To send or pass along.
U.S. Fish and Wildlife Service A research agency of the U.S. Department of the Interior, it was created in 1871 as the U.S. Commission on Fish and Fisheries. Fourteen years later, it acquired an office of ornithology (the science of birds). In 1905 it was renamed the Bureau of Biological Survey. It now has authority for research on and the conservation of land-based species, of freshwater species and of migratory birds.
U.S. Geological Survey (or USGS) This is the largest nonmilitary U.S. agency charged with mapping water, Earth and biological resources. It collects information to help monitor the health of ecosystems, natural resources and natural hazards. It also studies the impacts of climate and land-use changes. A part of the U.S. Department of the Interior, USGS is headquartered in Reston, Va.