Birdwatch News Archive
Everyone likes to see Greenfinches on their bird feeders, but it is this communal behaviour taht helps transmit the disease trichomonosis. Photo: Steve Young (www.birdsonfilm.com).
Finch disease continues to spread
Posted on: 22 Sep 2012
A new BTO study has shown that the finch trichomonosis disease has almost halved the population of Greenfinch across Britain, since the epidemic was first recognised in 2005.
The study, which used data from the Garden Bird Watch, Gardcen Bird Feeding Survey and the Breeding Bird Survey, shows that the British population of breeding Greenfinches has fallen from approximately 4.3 million to 2.8 million birds since the protozoan parasite disease’s emergence in 2005, and that the number of Greenfinches visiting gardens has also halved during this time. Chaffinches also suffer, but have been less severely affected, and the disease seems to be on the decline within that species.
Trichomonosis initially took hold in central and western parts of England and Wales, before spreading east and north into Scotland from 2007 onwards. Incidences were reported in Ireland from autumn 2007. This geographical expansion is thought to have occurred with the seasonal movements of infected individuals, as flocks move from Fennoscandia to Britain and Ireland and ack.
The study suggests that trichomonosis might have jumped to finches from Woodpigeon. Pigeon populations are traditional reservoirs of the parasite and, as they have similar food preferences at similar places, the spill-over from Woodpigeons to finches and subsequent transmission between finches could have taken place at shared feeding sites. This study has important implications for managing the on-going impact of the finch trichomonosis epidemic, and for assessing the likely effect of any future wildlife disease outbreaks. The team says that: "further investigation is required to determine the continuing impact of finch trichomonosis and to develop our understanding of how protozoal diseases jump host species."
Lawson, B, Robinson, R A, Colvile, K M, Peck, K M, Chantrey, J, Pennycott, T W , Simpson, V R , Toms, M P and Cunningham, A W. 2012. The emergence and spread of finch trichomonosis in the British Isles. Philosophical Transactions of the Royal Society of London B 367 doi: 10.1098/rstb.2012.0130.
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