Abstract
The gut microflora play a very important role in the life of animals. Although an increasing number of studies have investigated the gut microbiota of birds in recent years, there is a lack of research work on the gut microbiota of wild birds, especially carnivorous raptors, which are thought to be pathogen vectors. There are also a lack of studies focused on the dynamics of the gut microbiota during development in raptors. In this study, 16S rRNA gene amplicon high-throughput sequencing was used to analyze the gut microbiota community composition of a medium-sized raptor, the Eurasian Kestrel (Falco tinnunculus), and to reveal stage-specific signatures in the gut microbiota of nestlings during the pre-fledging period. Moreover, differences in the gut microbiota between adults and nestlings in the same habitat were explored. The results indicated that the Eurasian Kestrel hosts a diverse assemblage of gut microbiota. Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes were the primary phyla shared within the guts of adults and chicks. However, adults harbored higher abundances of Proteobacteria while nestlings exhibited higher abundances of Firmicutes and Actinobacteria, and consequently the majority of dominant genera observed in chicks differed from those in adults. Although no significant differences in diversity were observed across the age groups during nestling ontogeny, chicks from all growth stages harbored richer and more diverse bacterial communities than adults. In contrast, the differences in gut microbial communities between adults and younger nestlings were more pronounced. The gut microbes of the nestlings in the last growth stage were converged with those of the adults. This study provides basic reference data for investigations of the gut microbiota community structure of wild birds and deepens our understanding of the dynamics of the gut microflora during raptor development.
Highlights
In animals, microorganisms occur externally, such as on skin and feathers, and internally in the gastrointestinal and reproductive tracts of their hosts (McFall-Ngai et al, 2013; Colston and Jackson, 2016)
A total of 1,592,930 16S rRNA gene reads were obtained, with an average of 30,055 ± 1681 sequences per sample, from which 9096 operational taxonomic units (OTUs) were identified to be from gut microbiotas of 53 F. tinnunculus samples
Raptors are carnivorous and are often regarded as pathogen vectors; studies on age-related change of gut microbiota in raptors will lay an important foundation for subsequent research on the prevalence of enteropathogens and the consequences of particular bacterial consortia in bird host health
Summary
Microorganisms occur externally, such as on skin and feathers, and internally in the gastrointestinal and reproductive tracts of their hosts (McFall-Ngai et al, 2013; Colston and Jackson, 2016). In order to better understand the interactions between gut microbes and their hosts, studies of gut microbes conducted on singlespecies or multi-species host have been carried out in many animal groups including mammals Studies on avian gut microbiota have increased rapidly since 2014 (Hird et al, 2015; Kohl et al, 2018; Wang et al, 2019b; Capunitan et al, 2020; Cho and Lee, 2020; Song et al, 2020), remain heavily outnumbered by studies of mammals, and are dominated by research on domestic poultry (Cui et al, 2017) or captive-bred model species (Ding et al, 2020). Wild birds remain understudied despite their relevance for pathogen transmission and for understanding diet and environmental influences on gut microbial structure and function
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