It's not an easy time to be a conservationist. Between the climate crisis, single-use plastics and mass deforestation, the world's wildlife is under constant threat from what some scientists are calling a 'mass extinction event'. But an increasing number of programmes are attempting to shore up threatened species by reintroducing animals to places they once lived. These are the best-known and best-loved animals to have been reintroduced to their former habitats...

Perhaps the world's most famous – and controversial – reintroduction to date, it took conservationists six decades to return grey wolves to their historic home in Yellowstone National Park. While some species are carelessly killed off by changes to habitat or climate, Yellowstone’s wolves were mercilessly and deliberately exterminated by hunters in the 1930s. Often unfairly vilified in films and fables (looking at you Little Red Riding Hood), even the so-called ‘conservation president’ Theodore Roosevelt called them "the beasts of waste and destruction".

In the wolves’ absence elk numbers ballooned, grazing entire landscapes bare, and conservationists were finally granted permission to reintroduce 31 Canadian grey wolves to the park between 1995 and 1997. One of the pack leaders was promptly shot by a hunter in Montana (who went to jail), but his eight pups survived and started a bloodline shared by most of the park’s wolves today. Conservationists will feel vindicated by the decades since. When the wolves returned a congressman remarked that there would be a dead child within a year; 26 years on, there has not been a single recorded attack inside the park.

Read more about the conservation efforts in Yellowstone National Park

A rare example of a non-native species being artificially introduced by conservationists, European bison technically never lived in Britain pre-2022, but were chosen as suitable stand-ins for the globally extinct forest bison that roamed the country during the last Ice Age. In July, Britain’s first three wild bison wandered out of a paddock in the Wildwood Wildlife Park in Kent, soon to be joined by a young bull from Germany, intended to be the patriarch for the British bison baby boom.

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They’ve been away for millennia, but bison are considered a ‘keystone species’ – animals of such size and influence that they can manage an environment in ways humans can’t – and these woollen battering rams are now the UK's largest land animals by some margin. The programme will also shore up the precarious population of European bison on the continent, which came within a hair’s breadth of extinction during the 20th century. Every one of the 7,500 animals alive today is descended from just a dozen individuals bred in a Polish zoo in the 1920s, and the species was categorised by the IUCN as 'Extinct in the wild' until 1996.

Once widespread across northern India, even the world's fastest land animal could not outrun the hunter's gun. The country's last three known Asiatic cheetahs were shot dead by a maharajah as they rested beneath a tree in 1948. After an aborted attempt to import cheetahs from Iran in the late 1970s (derailed by the Iranian Revolution), eight animals made the 11-hour flight from Namibia in September 2022 on a chartered Boeing 747 widely nicknamed 'the cat plane', before being released into the Kuno National Park. 12 more cheetahs from South Africa are now set to join them, with more expected to follow.

The plan is not without its critics. Some experts believe the conditions in India will lead to unacceptably high mortality among the sub-Saharan animals, while others cite potentially deadly clashes with local leopards. The cheetahs were welcomed to their new home by Indian Prime Minister Narendra Modi on his 72nd birthday, and some observers have dismissed the whole affair as a 'PR exercise'. Is it? Only time will tell.

These remarkable ecosystems have bounced back from the brink

A massive three-phase reintroduction programme spanning 12 time zones, Operation Oryx has set the standard for international conservation over the last seven decades. In the 1960s, with the species teetering on the brink, a so-called 'world herd' of nine Arabian oryxes were transferred from Yemen, Saudi Arabia, Kuwait and London Zoo to Phoenix Zoo in Arizona – a decision that unquestionably saved these desert-dwellers from extinction.

By 1972 the species was extinct in the wild, but the 'world herd' flourished in Arizona's dry heat, and reintroductions began just a decade later. In Oman the oryx is a revered symbol, and the country welcomed the animals back with controlled releases in 1982, with Saudi Arabia, Israel, Jordan, Syria and the United Arab Emirates following suit. In 2011 the Arabian oryx was downlisted from 'Endangered' to 'Vulnerable', becoming the first ever mammal to go from 'Extinct in the wild' to not being on the IUCN Red List at all.

The word 'vulture' does not have positive connotations, but the loss of these raptors left a massive hole in the Alpine ecosystem when they were hunted to extinction in the early 20th century. Often nicknamed 'nature's binmen', the birds clean up dead matter and limit the spread of disease, but myths abounded that they were in league with the devil and would carry off small children – even though they solely feed on carrion.

In the late 1980s a captive breeding and release programme started slowly trickling vultures back into the valleys – based in five centres across Switzerland, Austria, Italy and France – and the first wild bearded vulture chick for almost a century was born in 1997. Progress has been slow, but today more than 300 birds (including 60 breeding pairs) patrol the Alpine peaks.

Check out the world's most beautiful natural wonders

The Eurasian lynx is not the most famous entry on this list, nor was it particularly near extinction, but we'd be surprised if any animal on Earth had been successfully reintroduced in quite so many places. Historically ranging from Scotland to the central steppes of Asia, this small big cat was absent from central Europe for a good two centuries, but has triumphantly returned to France, Switzerland, Slovenia, Croatia, the Czech Republic, Italy, Germany and Austria since the 1970s.

The UK might well be the next stop on the lynx's reintroduction tour. Studies suggest that Scottish woodlands could benefit from a healthy helping of lynx, as they would thin out Britain's overabundance of deer and limit overgrazing by keeping prey animals on the move. Not unlike the wolf, the lynx's long-term welfare relies on the good will of the people it must live alongside, so it seems responsible to point out that there's no record of any unprovoked attack by a lynx on a human.

It seems only reasonable that Tasmanian devils be found only on the Australian island of Tasmania, but 3,000 years ago this mini-but-mighty marsupial scampered across most of the mainland too. Known for their dogged temperaments, rasping cries and conspicuous fangs that can dismember carcasses in minutes like adorable, terrestrial piranhas, devil numbers in Tasmania have declined by 90% since the 1990s thanks to a contagious form of mouth cancer, and mainland reintroductions could help the embattled species stabilise.

From bloodthirsty domestic cats to rabbits with myxomatosis, non-native wildlife has played havoc with Australia's biodiversity for centuries, and it is thought that the reintroduction of a native predator might help bring balance back to the country's unique ecosystems. In 2020, 28 healthy devils were released with radio collars into a wildlife park north of Sydney, and the 2022 breeding season has yielded nine confirmed devil joeys so far.

See the best shots from this year's Australian Nature Photographer of the Year awards

Short, squat and distinctly pony-like, you would never guess that this agreeable equine was the world's last truly wild species of horse. Known as 'the P-horse' for short, Przewalski's horses (pronounced 'shuh-val-skee') have resisted repeated attempts at taming, preferring to endlessly roam the steppes of central Asia in packs. But as recently as the 1960s, harsh winters and overgrazed pastures left these defiant little horses staring down the barrel of total annihilation – extinct in the wild and kept alive mostly in European zoos.

With only 12 breeding individuals worldwide at the lowest ebb, it took some time for breeding programmes to coax the species off life support. It was not until the 1990s that conservationists felt bold enough to give the horses a run-out in the wild, and the first 16 Przewalski's horses arrived at Hustai National Park in Mongolia on World Environment Day in 1992. Three decades and many more reintroductions later, hundreds of horses patrol the plains of Mongolia and northwest China, and the species has been upgraded twice on the IUCN Red List to merely 'Endangered'.

A well-loved rodent with goofy front teeth, tousled fur and a big floppy tail, it wasn't hard to drum up public support for bringing beavers back to Britain. The animals have long been a reintroduction staple – there are currently 200 or so projects across Europe restoring beaver populations – but the UK was quite late to the party by releasing its first breeding pair in Scotland in 2009. The aquatic mammals were hunted to extinction in the UK in the 16th century, prized for their fur, their meat and a glandular secretion called 'castoreum', used in perfumes, medicines and flavourings.

The successful Scottish Beaver Trial debuted a pair of beavers from Norway in Knapdale Forest in 2009, and four tiny kits were born within the year. Trials have since been greenlit in several other locations – including Argyll, Devon, Dorset and the South Downs – and the new settlements are going from strength to strength. Britain's beavers have managed to exceed the plans of conservationists, as escapees have set up several unlicensed colonies in England that have retrospectively gained legal protection. Sometimes, life just finds a way.

The black-footed ferret is an outlier on this list in that it was thought to be fully extinct – not just in the wild – before making its improbable comeback. In 1979 the critter was declared gone forever until one turned up fortuitously (for the species, if not for the ferret) in the mouth of a rancher's dog in Wyoming two years later. A small colony was subsequently discovered outside the nearby town of Meeteetse, and all 24 remaining individuals were eventually captured and placed in a breeding programme.

A classic case of ecological damage moving up the food chain, black-footed ferrets suffered because their prey suffered. Prairie dogs make up 90% of an adult ferret's diet, and even a moderate prairie dog decline had devastating knock-on effects. Fortunately ferrets are efficient breeders, and their reward was a steady stream of releases through the 1990s and early 2000s. Ferret populations remain extremely precarious, and conservationists are focused on securing their food supply. Save the prairie dog; save the black-footed ferret.

As iconic American birds go, surely only the bald eagle occupies a higher perch than the California condor. Its 10-foot (3m) wingspan and 12kg (26lbs) bulk put it squarely among the largest and heaviest birds in the world (it's the biggest flying bird in North America), and historically its massive shadow loomed everywhere from Florida to the Canadian west coast. Their decline started centuries ago, but the use of lead in bullets – fatal for carrion-eaters that feed on hunted carcasses – pushed them almost to annihilation through the 20th century. In 1987 the last wild condors were captured and put into breeding programmes. There were only 27 individuals left on Earth.

Conservationists started releasing the birds back into the wild in 1992, but condors are long-lived creatures that mature and reproduce slowly, so it's taken decades to nurse the species back to health. In 2004 the first post-reintroduction chick was born in the wild, and there are now (relatively) stable colonies in California, Arizona and northern Mexico. The free-flying and captive population now tops 400, though the birds remain critically endangered. Perhaps most importantly, in 2019 California became the first US state to ban lead ammunition.

Now discover these beautiful creatures that could soon become extinct