Greenfinch are among the worst hit by the parasite
A parasite affecting birds and recently recorded in the Highlands will continue to kill garden species until they build up an immunity to it, a charity claims.
RSPB Scotland said people can play a part in fighting the spread of trichomoniasis by cleaning feeders and feeding areas.
Cases have been reported among greenfinch in Strathspey.
Though not transmittable to humans, the organisation warned people against handling dead birds.
Public agency Scottish Natural Heritage (SNH) confirmed the recent cases.
The parasite causes inflammation of the gullet and throat and can lead to a complete obstruction of an infected bird's upper digestive tract.
RSPB Scotland said it first surfaced in the UK in 2005 and has emerged every summer since.
A spokesman said: "Greenfinches are the main species affected, but other finches, as well as house sparrows, are also susceptible.
"There's no risk to humans, cats or dogs from the disease, and the best way to try and halt the spread is to keep all feeding areas clean and tidy.
If there is a bird affected in your garden, you can fill out a form and send it to us to help monitor the spread of the disease, and it's probably best to stop feeding for a couple of weeks so as not to infect other birds.
"Unfortunately it looks like something that will continue to affect greenfinches until they can hopefully develop a resistance."
SNH asked anyone who spots a dead finch in their garden to contact the Department for Environment Food and Rural Affairs.