Captive-bred mountain gazelles have been successfully released into the wild for the first time in 10 years.
Conservationists released 17 of the creatures into the Ibex reserve in Saudi Arabia.
The mountain gazelle (Gazella gazella) is at a high risk of extinction because of factors such as habitat loss and hunting.
Some of the gazelles have now been radio-tagged so scientists can track them as they explore their new home.
The radio collars will provide information about the dispersal and establishment of the animals on the reserve, as well as their survival.
"After many years of dedicated work to identify and conserve different species of gazelles in Saudi Arabia, it is fantastic to see a successful release of these elegant creatures," said Dr Richard Kock, head of the Deserts and Rangelands Conservation Programme at the Zoological Society of London (ZSL).
The gazelles were bred and raised at the King Khalid Wildlife Research Centre, in Thumamah, Saudi Arabia.