title: Emerging infectious disease leads to rapid population declines of common British birds.
abstract: Emerging infectious diseases are increasingly cited as threats to wildlife, livestock and humans alike. They can threaten geographically isolated or critically endangered wildlife populations; however, relatively few studies have clearly demonstrated the extent to which emerging diseases can impact populations of common wildlife species. Here, we report the impact of an emerging protozoal disease on British populations of greenfinch Carduelis chloris and chaffinch Fringilla coelebs, two of the most common birds in Britain. Morphological and molecular analyses showed this to be due to Trichomonas gallinae. Trichomonosis emerged as a novel fatal disease of finches in Britain in 2005 and rapidly became epidemic within greenfinch, and to a lesser extent chaffinch, populations in 2006. By 2007, breeding populations of greenfinches and chaffinches in the geographic region of highest disease incidence had decreased by 35% and 21% respectively, representing mortality in excess of half a million birds. In contrast, declines were less pronounced or absent in these species in regions where the disease was found in intermediate or low incidence. Also, populations of dunnock Prunella modularis, which similarly feeds in gardens, but in which T. gallinae was rarely recorded, did not decline. This is the first trichomonosis epidemic reported in the scientific literature to negatively impact populations of free-ranging non-columbiform species, and such levels of mortality and decline due to an emerging infectious disease are unprecedented in British wild bird populations. This disease emergence event demonstrates the potential for a protozoan parasite to jump avian host taxonomic groups with dramatic effect over a short time period.
authors.affiliation: British Trust for Ornithology, Thetford, Norfolk, United Kingdom.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Robinson
authors.forename: Becki
authors.initials: B
authors.lastname: Lawson
authors.forename: Mike P
authors.initials: MP
authors.lastname: Toms
authors.forename: Kirsi M
authors.initials: KM
authors.lastname: Peck
authors.forename: James K
authors.initials: JK
authors.lastname: Kirkwood
authors.forename: Julian
authors.initials: J
authors.lastname: Chantrey
authors.forename: Innes R
authors.initials: IR
authors.lastname: Clatworthy
authors.forename: Andy D
authors.initials: AD
authors.lastname: Evans
authors.forename: Laura A
authors.initials: LA
authors.lastname: Hughes
authors.forename: Oliver C
authors.initials: OC
authors.lastname: Hutchinson
authors.forename: Shinto K
authors.initials: SK
authors.lastname: John
authors.forename: Tom W
authors.initials: TW
authors.lastname: Pennycott
authors.forename: Matthew W
authors.initials: MW
authors.lastname: Perkins
authors.forename: Peter S
authors.initials: PS
authors.lastname: Rowley
authors.forename: Vic R
authors.initials: VR
authors.lastname: Simpson
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Tyler
authors.forename: Andrew A
authors.initials: AA
authors.lastname: Cunningham
mesh_terms: D000818:Animals; D001483:Base Sequence; D001715:Bird Diseases / Q000453:epidemiology* / Q000469:parasitology; D001717:Birds / Q000469:parasitology; D003141:Communicable Diseases / Q000662:veterinary*; D003625:Data Collection; D004196:Disease Outbreaks; D005260:Female; D008297:Male; D011157:Population Dynamics; D013997:Time Factors; D016834:Trichomonadida / Q000235:genetics / Q000502:physiology
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