Abstract
Provision of supplementary food for wild birds at garden feeding stations is a common, large-scale and year-round practice in multiple countries including Great Britain (GB). While these additional dietary resources can benefit wildlife, there is a concomitant risk of disease transmission, particularly when birds repeatedly congregate in the same place at high densities and through interactions of species that would not normally associate in close proximity. Citizen science schemes recording garden birds are popular and can integrate disease surveillance with population monitoring, offering a unique opportunity to explore inter-relationships between supplementary feeding, disease epidemiology and population dynamics. Here, we present findings from a national surveillance programme in GB and note the dynamism of endemic and emerging diseases over a 25-year period, focusing on protozoal (finch trichomonosis), viral (Paridae pox) and bacterial (passerine salmonellosis) diseases with contrasting modes of transmission. We also examine the occurrence of mycotoxin contamination of food residues in bird feeders, which present both a direct and indirect (though immunosuppression) risk to wild bird health. Our results inform evidence-based mitigation strategies to minimize anthropogenically mediated health hazards, while maintaining the benefits of providing supplementary food for wild birds.This article is part of the theme issue ‘Anthropogenic resource subsidies and host–parasite dynamics in wildlife’.
Highlights
With habitat loss, degradation and progressive urbanization, there is increased focus on the value that domestic gardens provide for wild birds
The methods used have evolved over this period in several ways, most notably involving a shift from opportunistic reports only (1992–2004) to an integrated system of independent opportunistic and systematic surveillance approaches (2005–present) [22], which has been greatly facilitated by expansion of an already existing national citizen science scheme [23]
The reason for the sharp decline in this endemic disease remains unknown, but we propose two potential hypotheses: first, that the decline in DT56(v) incidents reflects the development of herd immunity to this biotype and the populations are vulnerable to emergence of a new variant; or, second, that passerine salmonellosis has density-dependent transmission, and the dramatic reduction in greenfinch numbers in garden habitats, due to finch trichomonosis, has had a secondary impact on occurrence of this bacterial disease
Summary
Degradation and progressive urbanization, there is increased focus on the value that domestic gardens provide for wild birds. Citizen science offers a cost-effective means to undertake large-scale, year-round, longitudinal disease surveillance in conjunction with the monitoring of wildlife populations, their distributions and abundances [20] This approach lends itself to monitoring species, such as songbirds, that use peridomestic habitats and are positively perceived by the public [21]. For small passerines in North America, the investigation of the spread of house finch conjunctivitis is perhaps the best-studied example This has combined examination of field data, to provide information about spatio-temporal disease spread and house finch (Haemorhous mexicanus) population declines [24], with experimental studies to elucidate factors (e.g. behaviour) influencing Mycoplasma gallisepticum transmission We focus on three of the best-characterized and most frequently diagnosed infectious diseases, with contrasting modes of transmission, caused by a protozoal, a viral and a bacterial pathogen, each of which has been known to occur over the duration of the study period (1992– 2016) but for which the epidemiology, prevalence and impact have changed markedly over the past decade
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
