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Garden birds at risk from feeders


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.

Different strains

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.
   
Long-term monitoring like this shows that salmonellosis of garden birds is a more complex disease than we originally thought
Tom Pennycott
SAC Consulting Veterinary Service

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."

Infected garden feeders and bird baths blamed for deaths of one fifth of Britain's Greenfinches


For millions of cold and hungry birds, feeders hanging in gardens are a lifeline during the hard days of winter.

But some wildlife experts are warning that they can also be a deathtrap.

They say dirty feeders and infected bird baths are spreading a disease that has killed a fifth of Britain's greenfinches in recent years.

They are urging nature lovers to clean up their bird tables, and temporarily stop feeding birds if they are signs of infection in their garden.

Around 20 million people in Britain regularly leave out food for birds.

They spend £250million a year on specialist seeds and the figure is rising.

Charities and conservation groups say garden feeders are an essential resource for birds, especially during the winter.

But a conference in London next month will hear evidence that they have contributed to the spread of at least two diseases in last decade.

In Britain, around one in five greenfinches has been killed by the disease Trichomoniasis, or 'trich', since 2005.

The disease makes their throats swell, causing them to starve, New Scientist reports today.

In 2007, around 500,000 greenfinches were killed by trich according to the British Trust for Ornithology.

Other types of finches, pigeons and house sparrows are also susceptible.

The disease is caused by a parasite-that lives in the upper digestive-tract of birds and is spread when they feed each other, and when they visit tables and feeders contaminated by infected birds.

Birds with the condition have fluffed up plumage, are lethargic and may drool saliva.

In the U.S., dirty bird feeders are fuelling an epidemic of an infectious eye disease called mycoplasmal conjunctivitis, the conference will hear.

It has wiped out around 60 per cent of house finches in the eastern U.S.

Bird feeders can also be a source of salmonella and E-coli.

Dr Jim Reynolds, an ornithologist at the University of Birmingham, said little was known about the impact of bird feeders on wild populations.

'We should have a huge amount of data, but we don't,' he said.

The Royal Society for the Protection of Birds said feeders saved the lives of countless birds and should not be scrapped.

But Nik Shelton of the RSPB said: 'It's important that feeders and bird baths are hygienic to stop the spread of disease.'

'Bird tables should be cleared of food and scrubbed with weak bleach and water once a fortnight. Water containers should be washed out, and feeders should be washed.'

If greenfinches are showing signs of disease, people should stop feeding birds for a couple of weeks.