Plumage Bacterial Assemblages in a Breeding Wild Passerine: Relationships with Ecological Factors and Body Condition

Abstract

Microorganisms have been shown to play an important role in shaping the life histories of animals, and it has recently been suggested that feather-degrading bacteria influence the trade-off between parental effort and self-preening behavior in birds. We studied a wild breeding population of great tits (Parus major) to explore habitat-, seasonal-, and sex-related variation in feather-degrading and free-living bacteria inhabiting the birds' yellow ventral feathers and to investigate associations with body condition. The density and species richness of bacterial assemblages was studied using flow cytometry and ribosomal intergenic spacer analysis. The density of studied bacteria declined between the nest-building period and the first brood. The number of bacterial phylotypes per bird was higher in coniferous habitat, while bacterial densities were higher in deciduous habitat. Free-living bacterial density was positively correlated with female mass; conversely, there was a negative correlation between attached bacterial density and female mass during the period of peak reproductive effort. Bacterial species richness was sex dependent, with more diverse bacterial assemblages present on males than females. Thus, this study revealed that bacterial assemblages on the feathers of breeding birds are affected both by life history and ecological factors and are related to body condition.

Like mother like nest: similarity in microbial communities of adult female Pied Flycatchers and their nests

“…Given bacterial:fungal competitive interactions, these two findings are unlikely to be independent of one another. Sex-based differences in feather bacterial OTU richness have been observed previously (Saag et al 2011) but in reverse with females supporting higher OTU richness.…”

“…This is despite adult birds being both a source of microbes and the recipient of microbes originating from the nesting environment that could have a potential role in shaping avian life histories (Stewart and Rambo 2000). In one of the only studies on this topic, Saag et al (2011) showed plumage bacterial load of adult female great tits was higher in the nest-building period than when females were provisioning for chicks, possibly due to increased contact with nesting material. Additional support for this was offered by a follow-up study (Kilgas et al 2012), which showed that plumage bacterial load increased during the nest-building process.…”

“…Air swabs were taken by exposing an unused swab to the air for 10 s (the same time as for swabbing) and processing and plating as data swabs as per Lomardo et al (1996), Stewart and Rambo (2000), Goodenough and Stallwood (2010) to highlight any contamination problems. Post swabbing, all swabs were refrigerated at 4°C for a maximum of 7 days before processing as per Saag et al (2011).…”

Variation in Assemblages of Feather Bacteria in Relation to Plumage Color in Female Great Tits

“…following lucas et al (2003a), we separated the two types of bacteria in the laboratory and, to determine their density, counted free-living and attached bacteria directly with a flow-cytometry machine (bD lSR II). for tagging we used the DNA-binding dye SybR green (for further details see Saag et al 2011). bacterial densities are expressed per feather.…”

“…On the basis of earlier findings that higher chroma (Senar et al 2008, broggi andSenar 2009) and lower density of attached bacteria (Saag et al 2011) signal better individual quality of female great Tits, we predicted a negative association between chroma and bacterial density.…”