Noss Nature Reserve will close to the public from Friday, 1st July, to help protect the seabird population from bird flu.
And NatureScot will also advise people not to walk through colonies at Hermaness too – instead asking them to observe birds from a safe distance.
The measures are the latest in response to growing concern over the spread and impact of the current strain of avian flu, particularly in seabird colonies.
Large numbers of dead and sick seabirds have been reported in Shetland recently, with bonxies and gannets hardest hit.
NatureScot’s deputy director of nature and climate change, Eileen Stuart, said the decision to close Noss and a reserve on the Isle of May “has not been taken lightly”.
“We are increasingly concerned about the devastating impact avian flu is having in Scotland, particularly on our seabird colonies.
“The situation has been rapidly evolving and deteriorating, and we feel at this time that restricting access to these sites, and reducing it at others, is a precautionary but proportionate approach that gives us the best chance of reducing the spread of the virus and its impact.
“We recognise that this will be disappointing for those planning a visit but we hope people understand that this is about protecting our precious seabird populations for the future.
“Visitors will still be able to enjoy the summer seabird spectacle at both island reserves by taking round-island trips without coming ashore, and at other reserves by viewing from a short distance without crossing through colony areas.”