Parasitic disease is killing Britain’s greenfinches and finches

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UK owners should regularly clean their feeders and birdbaths to save greenfinches and finches from a nasty parasitic disease, experts say.

Trichomoniasis, a disease caused by the parasite Trichomonas gallinae, causes birds’ throats to swell and cause them to regurgitate food and starve to death.

Affected birds show signs of general illness – such as lethargy and swollen plumage – and may have difficulty swallowing or labored breathing.

Gardeners can unintentionally kill birds because dirty bird feeders and baths can spread the pathogen. Experts therefore urge them to clean them regularly.

Trichomoniasis has been killing greenfinches and finches for more than a decade, according to experts, who have published a new study on the disease’s effect on bird numbers.

Between 2008 and 2018 finch numbers fell by 29% in the UK, while 67% of the county’s greenfinches were lost, the study reveals.

Pictured is a common finch with trichomoniasis, spread through contaminated food and drinking water, or by birds feeding on regurgitated food during the breeding season. Garden owners can help slow transmission rates by ensuring garden bird feeders are cleaned regularly

WHAT IS TRICHOMONOSIS?

Trichomonosis is the name given to a disease caused by the protozoan parasite Trichomonas gallinae.

It has been recorded in a number of garden bird species and is widely accepted to be the causative factor in the rapid population decline of British Greenfinches which was first observed in late summer 2006 .

It can easily pass from bird to bird through contaminated regurgitated food and water and lead to premature death.

The disease is also known as “canker” when seen in pigeons and doves, and as “frown” when seen in birds of prey. It has been known for some time as a disease of cage birds.

Source: BTO

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 declines in finches that have occurred since highlight the importance of understanding the threats that affect the health of our garden birds and how the disease can negatively affect biodiversity,” said study co-author Dr. Becki Lawson of ZSL’s Institute of Zoology.

Experts say the public should follow good practice advice for feeding garden birds to reduce the spread of disease.

This includes regular cleaning of feeders and birdbaths and, if possible, rotating the position of feeders in the garden to avoid the accumulation of food waste in one area.

If sick birds are seen, temporarily suspending feeding will allow the birds to disperse and may reduce the risk of transmission.

Other species susceptible to T. gallinae infection may also be at risk, the researchers said, such as pigeons and doves.

Dr Michelle Reeve, head of BTO Garden BirdWatch, told MailOnline: ‘Hygiene is really important when it comes to feeding garden birds.

“We recommend that feeders are cleaned weekly with soapy water or a very weak solution of household bleach, and that fresh drinking water is provided daily.

“Only provide enough food for a day or two and remove any uneaten food after that time.

“Where possible, rotating the position of feeders around the garden and regularly cleaning the areas below will prevent the accumulation of food waste.

Between 2008 and 2018 finch numbers fell by 29% in the UK, while 67% of greenfinches in the county were lost

Between 2008 and 2018 finch numbers fell by 29% in the UK, while 67% of greenfinches in the county were lost

“If you spot a sick bird in your garden, 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, scientists looked at patterns of change in populations of greenfinches and finches since the emergence of trichomoniasis.

They found that the declines were due to reduced survival of adult birds, a pattern consistent with the high levels of disease observed.

Gardeners can unintentionally kill birds because dirty bird feeders and baths can spread the pathogen.  Experts therefore urge them to clean them regularly.  Pictured is a greenfinch perched on a birdbath

Gardeners can unintentionally kill birds because dirty bird feeders and baths can spread the pathogen. Experts therefore urge them to clean them regularly. Pictured is a greenfinch perched on a birdbath

The study also found that survival rates of greenfinches and finches were lowest in human-associated habitats.

Disease transmission may be higher in these environments, as birds often congregate at garden feeders.

Trichomonosis was first detected in finches in the UK in 2005. Greenfinches were initially the most affected, but now finches are dying at a much faster rate.

Due to the impact of the disease, the greenfinch was moved to the red list in the latest assessment of birds of conservation concern, published last year.

According to the 2021 assessment, the greenfinch moved from green list to red list after a population crash (62% since 1993) caused by trichomoniasis.

Other birds on the assessment’s red and amber list include house sparrows and bullfinches, which are also susceptible to the disease.

MORE THAN ONE IN FOUR BIRD SPECIES ‘IN BIG PROBLEM’, SAYS RSPB

More than one in four bird species in the UK need urgent conservation action, warns a new report from the RSPB.

Last December the charity revealed its latest assessment of the status of all 245 species of birds that regularly occur in the UK.

A total of 70 species, or 29% of the total, are now ‘of most conservation concern’ and have been placed on the assessment’s red list.

Bird species currently on the Red List – including the Swift, House Swallow and Greenfinch – are of “highest conservation priority” and require “urgent action”, mainly due to severe decline of the population, the RSPB said.

Each species has been assessed against a set of objective criteria and placed on the green, orange or red list, indicating a growing level of conservation concern.

Worryingly, the Red List now represents 29% of UK species, more than ever before, and almost double the figure (36 species) noted when it was first reviewed in 1996.

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