Cloacal microbiota of barn swallows from Northern Italy

Abstract

Bird gut microbiota shows large variation among geographical populations of the same species – probably because, differently from mammals, gut microbiota of birds is largely affected by extrinsic factors such as diet and environmental conditions. We analysed the cloacal microbiota (CM) of 12 barn swallows (Hirundo rustica) from a colony in Northern Italy by high-throughput DNA sequencing of the 16S rRNA gene. The CMs, dominated by bacteria of the phyla Proteobacteria, Actinobacteria, Firmicutes and Bacteroidetes, did not significantly differ between adult females, adult males and fledglings. This first description of barn swallow CM in Italy, together with two previous studies from Europe, suggests that CMs of geographically different barn swallow populations are dominated by bacteria belonging to the same phyla but different genera. The intra-colony similarity of the CMs may be due to the exposure of individuals to the same local environmental conditions while on their breeding grounds.

KEY WORDS:

• barn swallow
• gut microbiota
• Hirundo rustica
• Illumina sequencing
• microbiome

ACKNOWLEDGEMENTS

We warmly thank Piero Paloschi and the staff of the Cascina Sora riding school for allowing us to study barn swallows in their stables and Valentina Bertolini, Margherita Corti and Luca Ambrosini for assistance during field work. We also thank Prof. Riccardo Borgoni for advices on statistical analyses and Dr Alice Squassina and COPAN ITALIA SPA for providing swabs for sampling. COPAN ITALIA SPA had no role in designing experiments or in data analysis. We thank Javier Balbontin and two anonymous referees for constructive comments on an earlier version of the manuscript.

DISCLOSURE STATEMENT

No potential conflict of interest was reported by the authors.

SUPPLEMENTAL MATERIAL

Supplemental data for this article can be accessed at https://doi.org/10.1080/03949370.2017.1388294.

Additional information

Funding

This work was supported by the University of Milano Bicocca [grant number 2014-ATE-0437].