Using citizen science as a tool to investigate wild bird disease in peri-domestic habitats: Patterns of endemic and emergent disease in great britain

Background/Question/Methods

As a consequence of landscape change, agricultural intensification and urban development, private gardens have become an increasingly important habitat for free-living wildlife. Wildlife friendly-gardening is a common pastime with the British public. This close interface between the public and wildlife offers an ideal opportunity to utilise a citizen science approach for wildlife disease surveillance. Whilst anthropogenic provisioning has many associated benefits for wild birds, congregation of species in large numbers, interspecific mixing in close proximity and pathogen accumulation which can occur with poor hygiene conditions at garden feeding stations might increase opportunities for pathogen transmission and predispose to outbreaks of infectious disease. In 2005, the Garden Bird Health initiative was set up to investigate causes of mortality in British garden birds. A combination of two independent but complementary surveillance schemes were employed: opportunistic reports of garden bird mortality incidents were solicited from the general public and systematic surveillance on a weekly basis was undertaken by a citizen science network. Post mortem examinations were performed on a subset of incidents following a standardised protocol and set case definitions.

Results/Conclusions

In excess of 2500 post mortem examinations have been performed on over 60 garden bird species: these findings have revealed marked dynamism in these species’ disease ecology. Two previously known pathogens, one parasitic and the second viral, have emerged in new host species. Finch trichomonosis, caused by a single clonal strain of Trichomonas gallinae, is thought to have originated from sympatric British columbiforms. Seasonal epidemic mortality due to this EID has led to the decline of 35% (circa 1.5 million birds) of the UK greenfinch (Carduelis chloris) population within a 4-year period. Paridae pox has emerged as a cause of severe skin lesions, particularly in great tits (Parus major), with significant impact on individual bird survival and reproductive success. Incursion into south-east England of this strain of avian poxvirus is hypothesised to be from either Scandinavia or central Europe, where Paridae pox has previously been observed. The incidence of passerine salmonellosis, an endemic disease caused by host-adapted phage types of the bacterium Salmonella Typhimurium, has reduced markedly since 2008.

Citizen science offers a practical and cost-effective solution to achieve wildlife disease surveillance in peri-domestic habitats. Public engagement and education are important additional benefits of this approach.