Gloger's Rule, Feather-Degrading Bacteria, and Color Variation Among Song Sparrows

Variation in Plumage Microbiota Depends on Season and Migration

“…Previous studies strongly suggest that habitat type affects bacterial community composition of the plumage [3,5,6,22]. If bacteria can rapidly colonize the plumage of birds, migrant birds, which contact different habitats during their travels and in their summer and winter residences, should harbor a more diverse and abundant microbiota in their plumage than resident species, which occupy the same habitat year-round.…”

“…than aerial insectivores. Burtt and Ichida [5], Lucas et al [18], and Peele et al [22] showed that feather-degrading bacilli and plumage microbial communities varied geographically and locally among habitats. Although focusing on fecal microbes, Waldenström et al [33] found that Campylobacter spp.…”

Intraspecific Variation and Interspecific Differences in the Bacterial and Fungal Assemblages of Blue Tit (Cyanistes caeruleus) and Great Tit (Parus major) Nests

“…Recent studies have shown that birds have distinctive feather bacteria that influence plumage condition and colouring [10,11,52], complex conjunctiva and nasal bacterial assemblages [53] and diet-determined differences in gut bacteria [6,23]. Microbial loads and assemblages often differ between bird species (e.g.…”

“…those that decompose keratin through keritinase production) can also be important in the Aves due to their likely role in feather degradation. Microbe-induced feather degradation can potentially hinder flight (when wing feathers are involved) and mate attraction (when plumage condition or colour is important for mate selection), as well as thermoregulation [10,11,52]; although the extent and magnitude of such effects is currently unknown [24]. Keratinolytic microbes previously associated with birds include the bacterium Bacillus licheniformis [47] and the fungi Chrysosporium tropicum and Microsporum gallinae [27].…”

Flower colour: Gloger's rule isn't just for the birds

“…One explanation is that it arises as an adaptation against feather degradation by bacteria in moister climates 3 . The pigment responsible for much of the variation in darkness, eumelanin, improves feathers' resistance to both physical and chemical damage.…”