Linking migration and microbiota at a major stopover site in a long-distance avian migrant

Abstract

Migration is one of the most physical and energetically demanding periods in an individual bird’s life. The composition of the bird’s gut or cloacal microbiota can temporarily change during migration, likely due to differences in diets, habitats and other environmental conditions experienced en route. However, how physiological condition, migratory patterns, and other drivers interact to affect microbiota composition of migratory birds is still unclear. We sampled the cloacal bacterial microbiota of a long-distance migrant, the steppe buzzard (Buteo buteo vulpinus), at an important spring stopover bottleneck in Eilat, Israel, after crossing the ca. 1800 km Sahara Desert. We examined whether diversity and composition of the cloacal microbiota varied with body condition, sex, movement patterns (i.e., arrival time and migration distance), and survival. Early arrival to Eilat was associated with better body condition, longer post-Eilat spring migration distance, higher microbial α-diversity, and differences in microbiota composition. Specifically, early arrivals had higher abundance of the phylum Synergistota and five genera, including Jonquetella and Peptococcus, whereas the phylum Proteobacteria and genus Escherichia-Shigella (as well as three other genera) were more abundant in later arrivals. While the differences in α-diversity and Escherichia-Shigella seem to be mainly driven by body condition, other compositional differences associated with arrival date could be indicators of longer migratory journeys (e.g., pre-fueling at wintering grounds or stopover habitats along the way) or migratory performance. No significant differences were found between the microbiota of surviving and non-surviving individuals. Overall, our results indicate that variation in steppe buzzard microbiota is linked to variation in migratory patterns (i.e., capture/arrival date) and body condition, highlighting the importance of sampling the microbiota of GPS-tracked individuals on multiple occasions along their migration routes to gain a more detailed understanding of the links between migration, microbiota, and health in birds.

Seasonal and environmental factors contribute to the variation in the gut microbiome: a large-scale study of a small bird

“…In adult birds, there was no association between body condition and the gut microbiome diversity in Seychelles’ warblers Acrocephalus sechellensis (Worsley et al, 2021) or in white-crowned sparrows Zonotricia leucophrys (Phillips et al, 2018). Contrastingly, in adult female steppe buzzards Buteo buteo vulpinus body condition associated with higher gut microbiome diversity, but no effect was found in male birds (Thie et al, 2022). In our study, it could be that the birds had generally good body condition as they were the ones that had survived to the first winter post-fledging or to breeding season (Naef-Daenzer et al, 2001; Naef-Daenzer and Grüebler, 2008).…”

Host avian species and environmental conditions influence the microbial ecology of brood parasitic brown‐headed cowbird nestlings: What rules the roost?

“…The presence of a brood parasite nestling could induce changes in the microbiota of host chicks through stress or changes in food intake, as the BHCO parasite often outcompetes the host nestlings for food by begging more aggressively and, due to their larger size, being able to reach their mouths farther than that of the host nestlings (Lichtenstein & Sealy, 1998). These effects may impact the host nestling microbiome through the stress of decreased food availability causing physiological changes and alterations to the host immune system (Jawahar et al., 2022) and decrease in avian body condition which has been significantly associated with variation in microbiota composition (Thie et al., 2022). Alternatively, cowbirds are known to benefit from the presence of a host nestling; the presence of 1–2 host nestlings in the nest yielded a higher provisioning rate for the parasitic cowbird nestling, likely either due to the larger brood providing a stronger collective begging stimulus to the parents or due to the host parents being more receptive to the stimulus from their own progeny (Antonson et al., 2022; Kilner et al., 2004).…”

Early-life factors shaping the gut microbiota of Common buzzard nestlings

“…Certain microbial taxa can either enhance or diminish host condition, depending on their interactions with the current diet, host immunity and other members of the microbiota [93]. A study conducted on the steppe buzzard (Buteo buteo vulpinus) showed no correlation between body condition and microbiota community composition, but it revealed a significant increase in the relative abundance of the genus Escherichia-Shigella with decreasing body condition [107]. Studies highlighting connections between eukaryotic gut microbiota and health primarily focus on economically important species [103], with a scarcity of direct connections observed in the wild.…”