Six swans have been found dead, suspected of having contracted avian bird flu.
The swans were discovered at Rescobie Loch in Angus.
It is the latest incident after a fourth outbreak was detected on Saturday in Dumfriesshire, near Moffat.
A white tailed eagle was also earlier found dead on the Isle of Skye.
Scottish rural affairs secretary Mairi Gougeon urged the public not to touch or pick up any dead or sick birds.
“We know that avian influenza is here in Scotland,” she said.
“In order to try to keep their birds safe and stop the spread of the disease, producers and bird keepers are reminded to comply with the Order to house birds, which came in to effect on November 29, or to ensure their birds are kept separate from wild birds.
“It’s important that the public remain vigilant and report any findings of dead wild birds to the GB-wide helpline run by Defra. Do not touch or pick up any dead or sick birds that you find.”
Scotland’s chief veterinary officer Sheila Voas said keepers worried about the health or welfare of their flock should seek veterinary advice immediately.
“We have already made clear that all bird keepers – whether major businesses or small keepers with just a few birds – must ensure that their biosecurity is up to scratch to protect their birds from disease and prevent any contact between their birds and wild birds,” she said.
“Keepers who are concerned about the health or welfare of their flock should seek veterinary advice immediately.
“Your private vet, or your local Animal and Plant Health Agency office, will also be able to provide practical advice on keeping your birds safe from infection.
“Any dead wild swans, geese, ducks or birds of prey, or five or more dead wild birds of other species (including gulls) in the same location at the same time, should be reported to the GB-wide telephone helpline run by Defra.
“Public health advice is that the risk to human health from the virus is very low and food standards bodies advise that avian influenzas pose a very low food safety risk for UK consumers, and it does not affect the consumption of poultry products including eggs.”