Parasite threatens many of Britain’s best-loved birds

Scientists from the Garden Bird Health initiative (GBHi) discovered that trichomonosis, an emerging infectious disease of garden birds led to dramatic declines in greenfinch populations across much of England. The findings of their study are described in a paper published in the journal PLoS ONE this week.

 The study also revealed that chaffinch populations fell by up to 20%. Most birds died in the summer and autumn months, and outbreaks of the disease have continued to occur each year since its emergence in 2005.

 Dr Rob Robinson, a Principal Ecologist at the British Trust for Ornithology (BTO) joint lead author, commented “These findings demonstrate that virulent infectious diseases can cause sharp population declines in common wild birds in just a short period of time”.

 In order to determine the scale of the disease outbreak, the study used data drawn from public observation and a volunteer survey. Further data were collected through post mortem examination of hundreds of birds, which were collected from gardens across the country.

 Becki Lawson, a wildlife veterinarian from the Zoological Society of London and joint lead author, said “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”.

 Trichomonosis is well known in doves and pigeons but appears to have jumped the species barrier in 2005. The current effects of the disease in greenfinches and chaffinches highlight the highly unpredictable impact of parasites able to move between different species.

James Kirkwood, Chief Executive of the Universities Federation for Animal Welfare and founder of the Garden Bird Health initiative said “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 GBHi team is now investigating possible factors underlying the emergence of this disease in garden birds and its continued impact on our garden birds.

Members of the public can assist this ongoing project by reporting cases of disease or mortality in their garden birds – http://www.rspb.org.uk/advice/helpingbirds/health/sickbirds/greenfinches.asp