Differential influence of urbanisation on Coccidian infection in two passerine birds

Abstract

Urbanisation has the potential to increase the risk of parasitism on wildlife. Although some ectoparasite groups appear unaffected, different responses are hypothesised for parasites with simpler life histories such as gastrointestinal parasites. Red-browed finches (RBF) and the superb fairywrens (SFW), two native passerine birds affected by urbanisation, were examined for Coccidian parasites along an urbanisation gradient in New South Wales, Australia, in order to detect if prevalence might be directly related to the degree of urbanisation. Influence of urbanisation on Coccidian infection was differential. In RBF, the prevalence of Isospora increased significantly in more urbanised areas but prevalence did not change between breeding and non-breeding seasons. In contrast, in SFW, the degree of urbanisation did not significantly change with the degree of urbanisation, and season exhibited no significant effects on the prevalence of coccidians. Diet, behaviour and habits are suspected to be the most influential factors on the variation seen between both species where granivorous and gregarious species are significantly infected. Since the dynamics of urban wildlife-pathogen interactions is largely unexplored, more studies are needed to corroborate if this pattern of Isospora infections can be extended to other passerine birds in cities from Australia and overseas.