Microbial Communities on American Redstarts
By Gregory Gough
We all know that feathers are unique features to birds. Frequently overlooked is the fact that feathers also harbor a diverse micro-flora and fauna.
A single bird may carry organisms that range in size from larger ectoparasites such as feather lice (Phthiraptera: Ischnocera) to smaller microscopic organisms such as feather-degrading bacteria (e.g. Bacillus licheniformis) and fungi (e.g. Arthroderma spp.).
The Migratory Bird Center conducted a collaborative research project with Dr. Patrick Gillevet at George Mason University and Dr. Edward Burtt, Jr. at Ohio Wesleyan University which involved a broad survey of feather-degrading bacteria and fungi across and within species of the Neotropics.
A focal study species was the migratory American redstart. Resident birds on the redstart's breeding grounds (Maryland) and those on its wintering grounds (Jamaica) had different microbial communities than the redstart. In addition, the microbial community on the redstart was different in the fall, breeding season, and wintering season.
With the potential for migratory birds to spread microbes across diverse areas it is important to understand the microbe/migratory bird interaction.
This article summarizes the information in this publication:
Bisson, I., Marra, P.P., Burtt Jr, E., Sikaroodi, M. and Gillevet, P. 2009. Variation in plumage microbiota depends on season and migration. Microbial Ecology, 58: 212-220.
Migratory birds can be efficient dispersers of pathogens, yet we know little about the effect of migration and season on the microbial community in avian plumage. This is the first study to describe and compare the microbial plumage community of adult and juvenile migratory birds during the annual cycle and compare the plumage community of migrants to that of resident birds at both neotropical and nearctic locations. We used length heterogeneity PCR (16S rRNA) to describe the microbial assemblage sampled from the plumage of 66 birds in two age classes and from 16 soil samples. Resident birds differed significantly in plumage microbial community composition from migrants (R=0.238, P<0.01). Nearctic resident birds had higher plumage microbial diversity than nearctic migrants (R= 0.402, P<0.01). Plumage microbial composition differed significantly between fall premigratory and either breeding (R=0.161, P<0.05) or nonbreeding stages (R=0.267, P< 0.01). Six bacterial operational taxonomic units contributed most to the dissimilarities found in this assay. Soil microbial community composition was significantly different from all samples of plumage microbial communities (R=0.700, P<0.01). The plumage microbial community varies in relation to migration strategy and stage of the annual cycle. We suggest that plumage microbial acquisition begins in the first year at natal breeding locations and reaches equilibrium at the neotropical wintering sites. These data lead us to conclude that migration and season play an important role in the dynamics of the microbial community in avian plumage and may reflect patterns of pathogen dispersal by birds.
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