Intestinal microbiota of Nearctic‐Neotropical migratory birds vary more over seasons and years than between host species

Abstract

Seasonal migration of Nearctic‐Neotropical passerine birds may have profound effects on the diversity and abundance of their host‐associated microbiota. Migratory birds experience seasonal change in environments and diets throughout the course of the annual cycle that, along with recurrent biological events such as reproduction, may significantly impact their microbiota. In this study, we characterize the intestinal microbiota of four closely related species of migratory Catharus thrushes at three time points of their migratory cycle: during spring migration, on the summer breeding territories and during fall migration. Using observations replicated over 3 years, we determined that microbial community diversity of Catharus thrushes was significantly different across distinct time periods of the annual cycle, whereas community composition was more similar within than across years. Elevated alpha diversity in the summer birds compared to either migratory period indicated that birds may harbour a reduced microbiota during active migration. We also found that community composition of the microbiota did not substantially differ between host species. Finally, we recovered two phyla, Cyanobacteria and Planctomycetota, which are not commonly described from birds, that were in relatively high abundance in specific years. This study contributes to our growing understanding of how microbiota in wild birds vary throughout disparate ecological conditions and reveals potential axes across which an animal's microbial flexibility adapts to variable environments and recurrent biological conditions throughout the annual cycle.

Stopover habitat selection drives variation in the gut microbiome composition and pathogen acquisition by migrating shorebirds

“…Between-habitat comparison of the gut microbial community in nine species of Darwin’s finches showed that lowland versus highland habitat variation was a primary determinant the microbiome composition (Loo et al 2019 ). Interspecific comparisons also indicated that local environmental conditions may be considered a crucial driver of the gut microbiota composition in birds and their importance may even exceed the effects of phylogenetic relationships (Hird et al 2014 , Grond et al 2019 , Skeen et al 2023 ). In agreement with this hypothesis, we observed a relatively good clustering of individual microbiome composition by the stopover site habitat (within species), and this clustering was more apparent that the clustering by species.…”

Impact of Season on Intestinal Bacterial Communities and Pathogenic Diversity in Two Captive Duck Species

“…Seasonal variations in the gut microbiota have been reported in a variety of vertebrate lineages, including birds, reptiles, and mammals. Wild bird studies, such as those of hooded cranes, passerine birds, Catharus thrushes, and Sichuan partridges, have demonstrated that the seasonal modulation of the gut microbiota often corresponds to seasonal changes in diet [42,[48][49][50]. While research on homing pigeons given the same diet in the Netherlands suggests that temperature played a role in the seasonal variations in the composition of the gut bacterial community [11], this study presents the first evidence of seasonal effects on the gut bacterial community in captive wintering ducks in China.…”

The diet–intestinal microbiota dynamics and adaptation in an elevational migration bird, the Himalayan bluetail (Tarsiger rufilatus)

“…Migratory birds possess complex and diverse gut microbiomes due to their seasonal and extensive movements (Zhang et al., 2021 ). Recent studies have revealed the influence of migration and environmental factors on the interaction between diet and gut microbiota (Grond et al., 2014 ; Ryu et al., 2014 ; Skeen et al., 2023 ). Migratory birds face physiological challenges during long‐distance movements, including energy demands, environmental stress, and immunity, which result in weight loss and gastrointestinal atrophy (Buehler & Piersma, 2008 ; McWilliams & Karasov, 2001 ; Weber, 2009 ).…”