The new research was led by Veronika Gvoždíková Javůrková from the Department of Animal Science, Czech University of Life Sciences, Czech Republic. "Using quantitative PCR and DGGE profiling, we investigated feather microbial load, diversity and community structure among two allopatric subspecies of White-shouldered Fairywren, Malurus alboscapulatus that vary in expression of melanin-based vs. structural plumage coloration. We found that microbial load tended to be lower and feather microbial diversity was significantly higher in the plumage of black iridescent males, compared to black matte females and brown individuals.

"We show that the presence or absence of iridescent plumage, not melanised plumage per se, was associated with differences in feather microbiota in free-living populations of a tropical bird. Iridescent black males had the lowest feather microbial load, the highest microbial diversity and harboured a distinct microbial community relative to brown and matte black individuals of either. European Bee-eater (Merops apiaster) in Italy by Carlo Galliani.

Our findings regarding feather microbial load are inconsistent with a recent study investigating bacterial load on ornamental throat feathers in free-living population of spotless starling (Sturnus unicolor), which documented higher bacterial load on iridescent feathers compared to un-ornamented adjacent or female feathers. European Roller (Coracias garrulus) in Romania by Carlo Galliani.

"Most existing research has shown that feather microbial diversity and community structure are primarily driven by horizontal transmission of microbes from the environment. However, species-specific feather microorganisms that are able to produce antimicrobial substances, or particular chemical substances contained in preen gland secretions may also affect feather microbiota diversity. Coppery-headed Emerald (Elvira cupreiceps) in Monteverde, Costa Rica by Jadwiga Dabrowski‎.

Our data show that iridescent individuals originating from two geographically and ecologically distinct populations do not differ in feather microbial diversity and harbour similar microbial communities on their feathers. Due to the similarity in microbial communities between individuals living in different environments, it is unlikely that horizontal transmission of microbes from the environment drive differences we observe in microbiota communities. Instead, chemical composition of preen gland secretions or physical properties of iridescent feathers based on UV reflectance and absorbance of solar radiation may be more important contributors to feather microbiota diversity and community structure in iridescent individuals."