These animals went extinct in the wild.

Extinct across Central Europe since the 1800s, the Eurasian lynx has returned to several countries, including Switzerland, France, Italy, Austria and Germany, thanks to a series of reintroduction programs that began in the 1970s. However, the fragmentation of these populations is still a barrier and conservationists are now exploring ways to connect animals scattered in isolated groups across the continent. The Tasmanian devil hasn't always been restricted to Tasmania. Around 3,000 years ago, the cute marsupials once roamed across Australia but were forced out when dingoes arrived. Their numbers were further decimated by Devil Facial Tumor Disease (DFTD), a contagious form of cancer that killed 90% of the remaining population. In 2020, the creatures were reintroduced to a wildlife sanctuary in New South Wales in Australia, helping to expand the animal's population beyond its namesake island and control feral cat and fox numbers. Once widespread across the Yangtze River basin, the Chinese alligator's numbers declined drastically as much of their habitat was converted to rice fields. In 1999, a survey found around 100 animals in the wild at just 10 locations, but in 2001, captive breeding and reintroduction programs started returning small numbers of the reptiles to protected areas. In 2019, a further release of 120 alligators more than doubled the wild population. The Steppe bison was an important part of England's ecosystem until the giant mammals went extinct around 10,000 years ago. Now, Kent Wildlife Trust is leading a project to bring back its close relative, the European bison. The UK is one of the world's most nature-depleted countries, and the project hopes that as "ecosystem engineers" the bison will help to revive Kent's ancient woodland. The first herd is due to be released into woods near Canterbury in 2022 Adapted to desert life, the Arabian oryx can go long periods without water in its harsh, arid habitat. But having been hunted for its meat, hide and horns, the species disappeared from the wild in the 1970s. Since then, it has been reintroduced in Israel, Oman, Saudi Arabia, Jordan and the United Arab Emirates. The IUCN estimates more than 1,200 Arabian oryx live in the wild, with over 6,000 in captivity, and changed its status from "endangered" to "vulnerable" in 2011, reflecting the success of the reintroduction programs. The black rhino's population was decimated in the 20th century, with less than 2,400 left in the wild by the 1990s. In recent years, conservation efforts have more than doubled their numbers, and reintroduction programs are returning the rhino to countries and communities where it was entirely extinct. Translocating 3,000-pound animals like rhinos is no easy task: in the past decade, conservationists have started moving some animals from areas that can't be accessed by road, by helicopter -- hanging them upside down in the air. Robin Radcliffe (pictured), a researcher at Cornell University, studied how being hung upside down affects rhinos, and found that it's better for their health than lying them on their sides Between 1995 and 1997, 41 gray wolves were reintroduced to Yellowstone National Park. Their 70-year absence had a huge knock-on effect across the park's ecosystem: the elk population expanded unchecked, overgrazing on willow and aspen trees, and in turn, beavers had no food or shelter, and almost disappeared from the park too. As of January 2020, there were at least 94 wolves in the park, and more than 500 in the greater area, but the program has struggled to manage the population beyond the park's borders. There continues to be opposition from ranchers over concerns for livestock, despite the fact that only 2% of adult cattle deaths in 2015 were caused by predators, and of those only 4.9% involved wolves -- less than half the number of cattle killed by dogs. Wolves beyond the boundary of the park are offered little to no protection: in Wyoming, wolves can be hunted freely across 85% of the state Przewalski's horse has become one of the most iconic reintroduction success stories. The free-ranging horses of Central Asia's steppes went extinct in the wild in the 1960s, but a captive breeding program in 1985 sparked hope they could be brought back. A reintroduction program was launched in Mongolia in 1992, and as of 2018, it is estimated over 500 horses are roaming free in the country. China launched its own program in 2001, releasing the horses into semi-wild nature reserves for part of the year. Przewalski's horse also returned to Russia's Ural region in 2016, and there are plans for future reintroductions in Kazakhstan. The combined wild and captive population numbers around 1,900 today