Investigating the association between diet and infection with Trichomonas gallinae in the European turtle dove (Streptopelia turtur)

Trichomonas gallinae, a protozoan parasite infecting a wide range of birds, has been a cause3 for conservation concern since its recognition as an emerging infectious disease, having had4 notable impacts on several avian species, including causing widespread mortality in5 greenfinches (Chloris chloris), and chaffinches (Fringilla coelebs), and hindering the recovery6 of the endangered pink pigeon (Nesoenas mayeri). Horizontal transmission between birds7 congregating at feeding sites, such as those provided for conservation and species management8 purposes, is an important driver in the spread of T. galliane. Supplementary feeding is a key9 conservation intervention for the European turtle dove (Streptopelia turtur), which is declining10 across its range, driven at least partially by a loss of natural food resources. Due to the link11 between T. gallinae transmission and supplementary feeding, we consider the prevalence of12 this parasite amongst European turtle dove in relation to diet, in the first study to analyse these13 two factors in the decline of this species together. Using birds sampled from breeding and14 wintering grounds, the dietary composition of individuals was compared to the presence of T.15 gallinae, and specific T. gallinae strains. Dietary variation was summarised into two axes using16 detrended correspondence analysis, neither were associated with the presence of T. gallinae,17 or any specific strains. The proportion of diet accounted for by cultivated seeds did not affect18 parasite presence, despite the spread of this parasite being associated with supplementary19 feeding due to an increase in contact between potentially infected and uninfected birds20 gathering at high densities at feeding sites. Significant dietary overlap was observed between21 infected and uninfected individuals in all sites, with almost complete dietary overlap being22 observed in one breeding site. The level of dietary overlap between individuals infected with23 specific strains fluctuated between sampling seasons, indicating no consistent relationship24 between diet and infection status.