Temporal stability of gut microbiota in barn swallow

We performed 16S rRNA metabarcoding on an extensive set of gut microbiota (GM) from a long-distance migratory bird, the barn swallow (Hirundo rustica). Our data revealed clear GM differences among juveniles and adults as regards taxonomic and functional composition, diversity and co-occurrence network complexity. Multiple GM samples from the same juvenile or adult collected within single breeding seasons exhibited higher similarity than expected, as did adult GM samples over two consecutive years. Despite low effect sizes for GM stability over time at the community level, we identified an adult GM bacterial subset with relative abundances exhibiting significant temporal consistency, possibly inducing long-term effects on the host phenotype. Our data also indicate a slight maternal (but not paternal) effect on GM composition in social offspring.