After their capture, the animals were taken to the Highland Wildlife Park before being moved to Edinburgh Zoo where the surviving lynx will quarantine for 30 days.
Some conservation groups have been campaigning to have the wild cats reintroduced to Scotland.
Helen Senn, head of conservation at the RZSS, said: “Unfortunately overnight we’ve had the news that one of the lynx didnt make it.
“It was found dead this morning.”
She added that a full post mortem would be carried out.
