Bonxies have been found dead in Foula.
Avian flu is on the way to becoming “the most catastrophic threat to the life of birds”.
Nature lover Brydon Thomason, who runs travel agency Shetland Nature, said urgent action was needed to tackle the epidemic which continues to plague Shetland’s seabird population.
“It is unquestionably already on its way to becoming the most catastrophic threat to birdlife as we know it,” he said.
“All organizations/authorities that can must absolutely prioritize action.”
Local RSPB official Helen Moncrieff said she had “cried” after witnessing the dwindling number of birds on Noss.
She described the experience as “both awesome and awful”.
“So many birds dead and dying from bird flu,” she said.
“I cried. Again. Yet another anthropogenic pressure on such magnificent birds that bring us joy.
“We owe them. We need to share their story and take action.
Concerns have already been raised that thousands of birds may have been killed by bird flu.
Nature Scot says bird flu continues to affect wild bird populations across the country.
Anyone who sees a dead wild bird is advised not to touch it, but to contact Defra’s UK National Helpline on 03459 33 55 77.