Pigeon disease kills one in three greenfinches

Michael McCarthy,Environment Editor
Thursday 19 August 2010 00:00
Comments

Populations of greenfinches, among Britain's most handsome and popular garden birds, dropped by a third in parts of England within a year of the emergence of a new disease, a new study reports.

Scientists from the Garden Bird Health initiative discovered that greenfinches declined dramatically after trichomonosis, a disease normally associated with pigeons, apparently "jumped the species barrier" and began to affect finches in 2005.

Populations of chaffinches were also hard hit, their numbers falling by up to 20 per cent in some places, and other garden birds were affected.

The cause of the disease is a parasite, Trichomonas gallinae, well known as a cause of disease in pigeons and doves, and in birds of prey that feed on them, but not hitherto in songbirds.

The parasite is vulnerable to dryness and cannot survive for long periods outside its host, so transmission of infection is most likely to be through birds feeding one another with regurgitated food during the breeding season; or through food or drinking water contaminated with saliva.

Outbreaks of trichomonosis are most severe and frequent between August and October, when sick birds tend to stay close to feeders and sources of water, and often die there.

The findings of the study, which is described in a paper published in the online journal PLoS ONE this week, show that most birds died in the summer and autumn months, and that outbreaks of the disease have continued to occur each year since its emergence in 2005.

"These findings demonstrate that virulent infectious diseases can cause sharp population declines in common wild birds in just a short period of time," said Dr Rob Robinson, a principal ecologist at the British Trust for Ornithology and one of the lead authors of the paper.

To determine the scale of the disease outbreak, the study used data drawn from public observation and a volunteer survey. Further data came from post-mortem examinations of hundreds of birds collected from gardens across the country.

"This citizen science project highlights the valuable role that volunteers can play in helping us learn more about wildlife diseases, even by just watching birds in their gardens for a couple of hours each week," said Becki Lawson, a wildlife vet from the Zoological Society of London and another lead author of the study.

The Garden Bird Health initiative was established in 2003 to develop guidelines about how best to feed garden birds so as to maximise the benefits in terms of their conservation and welfare.

James Kirkwood, chief executive of the Universities Federation for Animal Welfare and founder of the initiative commented: "Health surveillance of British wildlife species is crucial for us to recognise new and emerging disease threats that not only adversely affect the welfare of individual animals, but have the potential to impact entire populations."

The Garden Bird Health initiative team is now investigating possible factors underlying the emergence of this disease and its continued impact.

Register for free to continue reading

Registration is a free and easy way to support our truly independent journalism

By registering, you will also enjoy limited access to Premium articles, exclusive newsletters, commenting, and virtual events with our leading journalists

Please enter a valid email
Please enter a valid email
Must be at least 6 characters, include an upper and lower case character and a number
Must be at least 6 characters, include an upper and lower case character and a number
Must be at least 6 characters, include an upper and lower case character and a number
Please enter your first name
Special characters aren’t allowed
Please enter a name between 1 and 40 characters
Please enter your last name
Special characters aren’t allowed
Please enter a name between 1 and 40 characters
You must be over 18 years old to register
You must be over 18 years old to register
Opt-out-policy
You can opt-out at any time by signing in to your account to manage your preferences. Each email has a link to unsubscribe.

Already have an account? sign in

By clicking ‘Register’ you confirm that your data has been entered correctly and you have read and agree to our Terms of use, Cookie policy and Privacy notice.

This site is protected by reCAPTCHA and the Google Privacy policy and Terms of service apply.

Join our new commenting forum

Join thought-provoking conversations, follow other Independent readers and see their replies

Comments

Thank you for registering

Please refresh the page or navigate to another page on the site to be automatically logged in