A conservation trust based in Jersey said a rewilding project on a huge estate will be its first in Scotland.
Durrell Wildlife Conservation Trust said its bold plan for the Dalnacardoch Estate in Perthshire would leave its 18,500 acres "pulsing with life". The 100-year project includes the recovery of rare bird species the capercaillie.
Dr Lesley Dickie, Durrell's CEO, said it marked a "transformational moment" for Durrell.
She said the UK was among the world's most nature-depleted countries with "diminished species and missing ecological functions".
Leasing the "degraded" Dalnacradoch estate, which sits mostly within the Cairngorms National Park, was an "incredible opportunity", she added.
She said their work would "transition" the estate to a "nature-positive landscape" to benefit local people and wildlife.
Prof Carl Jones MBE, Durrell's chief scientist, said Durrell would bring with it "six decades" of experience in saving species from extinction and rebuilding ecosystems. "We look forward to restoring the plant and animal communities of Dalnacardoch so that the glens and moors are vibrant with bird song and pulsing with life," he added.
Among goals cited by the charity was to recover the capercaillie, a bird facing extinction in Scotland. It would also manage a "transition away" from the estate's historic use as a sporting estate, towards activities to provide "economic, social and environmental benefits".
Ecological audits were already under way, it said, with the team's "immediate focus" to engage with neighbouring estates and potential partners.
Grant Moir, chief executive of the Cairngorms National Park Authority, said the collaboration would be "vital" in areas including ecological restoration, woodland expansion and achieving net zero. The land was bought earlier this year by a family foundation with charitable aims, specifically with the intent to lease it to Durrell for a rewilding project, the charity said.