Bacteria as an Agent for Change in Structural Plumage Color

Recent studies have documented that a diverse assemblage of bacteria is present on the feathers of wild birds and that uropygial oil affects these bacteria in diverse ways. These findings suggest that birds may regulate the microbial flora on their feathers. Birds may directly inhibit the growth of harmful microbes or promote the growth of other harmless microbes that competitively exclude them. If keratinolytic (i.e., feather-degrading) bacteria degrade colored feathers, then plumage coloration could reveal the ability of individual birds to regulate microbial flora. We used field- and lab-based methods to test whether male eastern bluebirds (Sialia sialis) with brighter blue structural plumage coloration were better able to regulate their microbial flora than duller males. When we sampled bluebirds in the field, individuals with brighter color had higher bacterial loads than duller individuals. In the lab, we tested whether bacteria could directly alter feather color. We found that keratinolytic bacteria increased the brightness and purity, decreased the ultraviolet chroma, and did not affect the hue of structural color. This change in spectral properties of feathers may occur through degradation of the cortex and spongy layer of structurally colored barbs. These data suggest that bacteria can alter structural plumage color through degradation.

Criminology · Political science · Restorative justice · Social justice · Sociology · Labor Movements and Unions · Political and Economic history of UK and US · Religion, Society, and Development

• The globalization of crime control—the case of youth and juvenile justice

  Open Access•John Muncie•Theoretical Criminology•2004

  Incluir item

• Restorative justice in the criminal justice curriculum

  Susan L Smith-Cunnien, Peter F Parilla•Journal of Criminal Justice…•2001

  Incluir item

• Repenalisation and Rights

  Open Access•John Muncie•The Howard Journal of Criminal…•2006

  Incluir item

• Microbial Contributions to Primate Reproduction

  Open Access•Silvia Carboni, Abigail E Asangba et al.•Evolutionary Anthropology Issues…•2026

  Incluir item

• Heritable True Fitness and Bright Birds

  Open Access•William D Hamilton, Marlene Zuk•Science•1982

  Incluir item

• Pathogens and the Evolution of Primate Sociality

  Open Access•W J Freeland•Biotropica•1976

  Incluir item