Health hazards to wild birds and risk factors associated with anthropogenic food provisioning

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’.

Anthropogenic resource subsidies and host–parasite dynamics in wildlife

“…Lawson et al [39] present findings on the long-term surveillance of wild birds in Great Britain and infections by protozoan (finch trichomonosis), viral (Paridae pox) and bacterial (salmonellosis) pathogens. In each case, human activities influence transmission dynamics, but in different ways.…”

Exploring the motivations for garden bird feeding in south-east England

“…Given its scale and popularity, wild bird feeding is almost certainly the most important and potentially malleable form of gardening for wildlife practices (Fuller et al 2008, Jones andReynolds 2008). However, the practice of bird feeding can also be detrimental to birds, for example by facilitating transmission of diseases between birds visiting feeding stations (Lawson et al 2018). Thus, obtaining a detailed and reliable perspective on the motivations associated with bird feeding is timely (Jones 2011).…”

Spatio-temporal dynamics and aetiology of proliferative leg skin lesions in wild British finches

“…perches, tables). However, it is not possible with the available data to evaluate the relative importance of risk factors for occurrence of finch leg lesions, and the extent to which supplementary feeding may alter their occurrence 33 . It is important to note that anecdotal reports are available from ringers of chaffinches with leg skin lesions, from across habitat types (RAR pers.communication ), and that this is a gregarious species with opportunities for intraspecific contact 34 .…”