British homeowners should clean their bird feeders and bird baths regularly to keep greenfinches and chaffinches from a nasty parasitic disease, experts say.
Trichomonosis, a disease caused by the parasite Trichomonas gallinae, causes birds’ throats to swell, causing them to vomit food and starve.
Affected birds show signs of general illness — such as lethargy and ruffled feathers — and may show difficulty swallowing or shortness of breath.
Gardeners could unwittingly kill the birds, as dirty feeders and bird baths can spread the pathogen, which is why experts are urging them to clean them regularly.
Trichomonosis has been killing greenfinches and chaffinches for over a decade, according to experts who have published a new study into the disease’s impact on bird populations.
Between 2008 and 2018, chaffinch numbers in the UK fell by 29 per cent, while 67 per cent of the county’s greenfinches were lost, the study shows.
Pictured is a common chaffinch suffering from trichomoniasis, transmitted through contaminated food and drinking water or through birds feeding each other vomited food during the breeding season. Garden owners can help slow down transmission rates by making sure garden bird feeders are cleaned regularly
The research was carried out by the British Trust for Ornithology (BTO) and the Institute of Zoology (IoZ) of the Zoological Society of London (ZSL).
“The emergence of trichomoniasis in 2005, and the dramatic decline in finches that have occurred since then, underscores the importance of understanding threats affecting the health of our garden birds and how diseases can negatively impact biodiversity,” said co-author of the study, dr Becki Lawson from the ZSL Institute of Zoology.
Experts say the public should follow best practice advice on feeding garden birds to reduce the spread of disease.
This includes regularly cleaning bird feeders and bird baths and, if possible, rotating the position of bird feeders in the garden to avoid food waste accumulating in one area.
If sick birds are seen, temporarily stopping feeding allows the birds to disperse and may reduce the risk of transmission.
Other species susceptible to T. gallinae infection may also be at risk, say the researchers, such as pigeons and pigeons.
dr Michelle Reeve, manager of BTO Garden BirdWatch, told MailOnline: “Hygiene is really important when it comes to feeding garden birds.
“We recommend cleaning the feeders weekly with soapy water or a very weak household bleach and providing fresh drinking water daily.
“Only provide enough food for a day or two and remove any food that has not been eaten after that time.
“Where possible, feeders can be rotated around the garden and areas underneath regularly cleaned to prevent food waste from building up.
Between 2008 and 2018, the UK’s chaffinch population fell by 29 per cent, while 67 per cent of the county’s greenfinches were lost
“If you spot an unwell bird in your yard, stop feeding for two weeks to encourage the birds to disperse.
“These measures should reduce the risk of transmission of trichomoniasis and other diseases.”
The BTO adds that Trichomonas gallinae is a parasite of birds and poses no health risk to humans or their pets.
For the study, published in Scientific Reports, the scientists examined patterns of change in populations of greenfinches and chaffinches since the onset of trichomoniasis.
They found that the declines were caused by a reduction in adult bird survival, a pattern consistent with the high disease rates observed.
Gardeners could unwittingly kill the birds, as dirty feeders and bird baths can spread the pathogen, which is why experts are urging them to clean them regularly. Shown, a greenfinch on a bird bath
The study also found that greenfinch and chaffinch survival rates were lowest in human-like habitats.
Disease transmission may be higher in these environments as birds often congregate at garden feeding stations.
Trichomonosis was first identified in British finches in 2005. Initially, greenfinches were hit the hardest, but now chaffinches are dying much faster.
Due to the impact of the disease, the greenfinch was redlisted in the latest Birds of Conservation Concern assessment, published last year.
According to the 2021 assessment, the greenfinch was moved from the Green List to the Red List after a population crash caused by trichomoniasis (62 percent since 1993).
Other red and yellow birds in the assessment include the house sparrow and bullfinch, which are also susceptible to the disease.
