Bird lovers are advised to clean feeders regularly
Researchers at the Scottish Agricultural College (SAC) are concerned that garden bird feeders could be putting birds at risk.
A 13-year study has found that the salmonella infection can build up on feeders and then spread among birds.
The study revealed that greenfinches and house sparrows appeared to be particularly vulnerable to the disease.
Bird lovers are being advised to disinfect feeders regularly to minimise the risk of infection.
The research has been published in the journal, The Veterinary Record.
Tom Pennycott, from the SAC consulting veterinary service, examined the findings from 198 incidents of salmonellosis in garden birds in Scotland between 1995 and 2008.
The research also found that in the north of Scotland, finches, especially greenfinches, were most commonly affected, but in the south of Scotland, the salmonella infection was found in house sparrows.
The long-term survey also highlighted significant differences in the strains of salmonella found in the north and the south of Scotland.
In the north, one type predominated but in the south of Scotland two types were commonly found.
However salmonella was not the only challenge facing our garden birds.
Long-term monitoring from 1995 identified a recent dramatic fall in the number of greenfinches found dead from salmonellosis.
For the first three years of the survey, 34 of 36 garden birds with salmonellosis were greenfinches.
In the past three years, to the end of March 2010, only eight of 38 infected birds were greenfinches.
Mr Pennycott believes the reduction in greenfinches found with salmonella may be to do with a more significant overall fall in greenfinch numbers.
He said this may be due to another infection of garden birds, called trichomonosis, which was first diagnosed by SAC veterinary services in Scotland in 2005 and has since become widespread in Britain.
He said: "Long-term monitoring like this shows that salmonellosis of garden birds is a more complex disease than we originally thought.
"And when another disease such as trichomonosis appears out of the blue, the combined effects can be disastrous.
"Members of the public can play a key role in all this, by maintaining good hygiene at bird feeders and by alerting us if they find unusually large numbers of dead birds."