Wild asses are returning to the grasslands of Kazakhstan where they once roamed in large numbers.
The equine animals, known as kulans, are native to the area but have been pushed to the brink of extinction by illegal hunting and loss of habitat.
Conservationists have started reintroducing the horses to their natural landscape.
This month, more kulan were released in the Altyn Dala nature reserve to establish a fourth population.
The project is being organised by the Association for the Conservation of Biodiversity of Kazakhstan (ACBK).
Sergey Sklyarenko said reintroduction started in a reserve on an island in the Aral Sea with fewer than 20 animals.
"We have got to now about 4,000 kulans in three wild populations," he said.
"The creation of a fourth population will allow to provide new areas for the species and increase its sustainability."
The wild asses were captured in the Altyn Emel National Park in the autumn.
The population there has reached about 3,000 individuals, but there is little potential for future growth.
The kulans were moved to a centre at Alytn Dala in Central Kazakhstan, where they were kept in captivity over the winter to allow them to bond and adjust to local conditions.
Mares have been fitted with GPS collars so that the movement of herds can be tracked.
The animals have already started exploring the area, and it is hoped that they will thrive and breed.
Asian wild ass once ranged across the Russian Federation, Mongolia, northern China, northwest India, Central Asia, and the Middle East.
Today their main stronghold is southern Mongolia and China.
The Equus hemionus (Asian Wild Ass, Asiatic Wild Ass) is listed as Endangered, and considered to be facing a high risk of extinction in the wild, on the IUCN Red List of Threatened Species.
Although they are a protected species, they are hunted for their meat and their skins in some areas.