Keepers at the RZSS Highland Wildlife Park are carrying out pioneering work to help save the rarest big cat in the world – the Amur leopard.
Construction recently finished on a very large facility for new couple - Freddo and Arina - at the attraction by Kincraig.
It’s been a hush hush operation so far with the two leopards moving on site last year but they were just introduced recently in their new home.
Keepers said it encloses a wonderful portion of natural Highland habitat that despite its high profile inhabitants, will not be on show to visitors.
Douglas Richardson, Head of Living Collections, RZSS Highland Wildlife Park, said: "Earth Day tomorrow is about celebrating environmental protection and conservation.
"At RZSS we have some very exciting conservation projects which are challenging traditional perceptions of zoos.
"Most zoos today exhibit animals which are threatened species, whose zoo populations are maintained as part of a wider conservation effort.
"At RZSS Highland Wildlife Park, we are going one step further.
"A specially designed, off-show, breeding complex for Amur leopard is now complete and it was made possible due to a very generous anonymous donation.
"As the park has large, undeveloped areas, it gave us the opportunity to build an extensive leopard facility that would allow us to produce and rear cubs that were not familiar with humans, making them directly eligible for the Russian reintroduction project."
RZSS Highland Wildlife Park focuses on cold weather adapted species and has had notable breeding success with a range of threatened carnivores and the addition of Amur leopards intends to build on that success.
The male, Freddo, was born in Tallinn Zoo in Estonia and Arina was reared at Twycross Zoo in the Midlands. Both were born in 2014.
Mr Richardson said: "If our leopards produce and rear cubs this year, we could be in a position to return cats to Russia by mid to late 2018, which is very exciting as our approach will dramatically abbreviate the reintroduction process.
"Our Amur leopards will never be on show to our visitors but we hope to create an information hub that will explain all about this exciting conservation project and hopefully educate people about the plight of these animals."
Although now better protected, the population of Amur leopards is less than 70 remaining in the wild.
Classed as Critically Endangered on the IUCN Red List they had been illegally hunted for their coat and other body parts for the traditional medicine trade.
The proposed release site in Russia is now completely devoid of leopards and so the reintroduction project hopes to return the leopard to this part of their historical range.