Zoos can effectively work together to conserve some of the endangered animals. Zoos have the necessary knowledge and experience in animal care, veterinary medicine, animal behavior, reproductive biology, and genetics to establish captive animal populations of endangered animals.

Seven North American zoos are joining with universities and the Defenders of Wildlife to form breeding colonies of endangered amphibians as part of the Panama Amphibian Rescue and Conservation Project. 

Here are best and successful examples of the zoos in the world.

IUCN pinpointed "After the 'rediscovery' of the Przewalski's Horse for western science, western zoos and wild animal parks became interested in this species for their collections." About 200 horses are covered by this program, and purebred Przewalski's horses are now well established in captivity.

Przewalski's wild horse

Excessive hunting, competition with domestic stocks, and interbreeding with domestic horses have effectively caused the extinction of purebred of Przewallski's horse in the wild. Przewalski's wild horse (Equus przewalskii)  is named after the Russian general who discovered it while exploring Central Asia in 1879. 

International Union for Conservation of Nature and Natural Resources (IUCN) said, "Przewalski's wild horse previously listed as Extinct in the Wild (EW) from the 1960s up to the assessment in 1996. The species was then reassessed as Critically Endangered (CR) due to at least one surviving mature individual in the wild. Successful reintroductions have qualified this species for reassessment. The population is currently estimated to consist of more than 50 mature individuals free-living in the wild for the past seven years." 

But who did save Przewalski's wild horse from extinction vortex? Zoos. Przewalski's wild horse were never domesticated but kept as a rarity in zoos. From a low point of just 13, animal numbers have been steadily increasing, and over 1,000 have been born in zoos. As a result of the small number of horses involved early on, inbreeding was a problem, leading to poor breeding success and low survival rates. 

However, zoos in Europe, North America, and the former Soviet Union collaborated constructively to manage a cooperative breeding program that aimed to share animals and to avoid mating between close relatives. 

IUCN pinpointed "After the 'rediscovery' of the Przewalski's Horse for western science, western zoos and wild animal parks became interested in this species for their collections." About 200 horses are covered by this program, and purebred Przewalski's horses are now well established in captivity.

Many generations of captive breeding, artificial food, confinement in small enclosures, and living in mild climates away from Central Asia may all combine to reduce the ability of the animals to survive in the extreme conditions of their native home. 

In 1989 an experiment was started at the Bukhara Breeding Center in Uzbekistan to find out whether horses bred for generations in zoos could actually survive the challenge of living wild in the semi-desert conditions of Central Asia. A stallion and four mares were released into a huge fenced area and studied.

The horses seemed to manage well; they bred successfully and didn't suffer ill-effects from mixing with wild asses also present in the area. Efforts being made to restore Przewalski's horse to the wild in Mongolia, where they have begun to breed successfully in a protected reserve. 

IUCN confirmed that Mongolia was the first country where truly wild reintroduced populations existed within the historic range. Reintroductions in Mongolia began in the Great Gobi B Strictly Protected Area in the Dzungarian Basin (9,000 km2) and Hustai National Park in Mongol Daguur Steppe (570 km2) in 1994. A third reintroduction site, Khomintal, (2,500 km2), in the Great Lakes Depression, was established in 2004, as a buffer zone to the Khar Us Nuur National Park in Valley of the Lakes. Releases began in the Kalamaili Nature Reserve (17,330 km2), Xinjiang Province, China in 2001 and in the Dunhuang Xihu National Nature Reserve (6,600 km2), Gansu Province, China in 2010, although almost all of these animals are corralled and fed in winter. Further reintroduction sites are planned in Kazakhstan and Russia.

Zoos in Europe, North America, and the former Soviet Union collaborated constructively to manage a cooperative breeding program that aimed to share animals and to avoid mating between close relatives.

Arabian Oryx

In the vast deserts of the Middle East the oryx was hunted to extinction in the 1970s. It has now been reintroduced to the wild from captive herds bred in zoos. Arabian oryx lives in small herds, usually with fewer than 10 animals per group, which lessens the impact of their feeding on the sparse desert vegetation. Big-game hunters used to pursue oryx for trophies, and for generations the animals were hunted by men riding on camels. Although some escaped, many did not, and they were steadily eliminated from countries such as Syria and Egypt. 

By the 1950s the increased availability of four-wheel drive vehicles, abundant fuel, automatic rifles, and oil based local wealth combined to make hunting in Arab countries both more widespread and more efficient. Gunmen in vehicles hunted the animals to extinction. The last wild oryx were killed in the 1970s. 

Fortunately, several Arab countries had already made efforts to keep and breed the oryx in captivity. In 1962 international cooperation between zoos made it possible to assemble a few animals in Phoenix, Arizona (where the climate is very similar to that of the native home of Arabian oryx), from which to breed animals specifically for release back into the wild. This was the first such international project for any endangered or extinct species, and it has been highly successful. 

Oryx were released in Oman in 1982, Jordan in 1983, and Saudi Arabia in 1990. As IUCN confirmed, "An estimated 6,000-7,000 animals are held in captivity worldwide, most of them on the Arabian Peninsula. Some of these are maintained in large fenced enclosures, receiving various amounts of supplemental food and care, including those in Qatar, Saudi Arabia, Bahrain, and UAE.
The reintroduced population in Oman reached a high point of 450 in 1994 when illegal live capture began and severely reduced numbers. Many of the released animals were taken back into captivity for security."