Feather Degrading Bacteria Studied

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The existence of feather degrading bacteria in wild birds was only discovered for the first time approximately ten years ago. This natural phenomenon has therefore been plaguing ornithologists with more questions than answers and sparked the undertaking of the recent studies done to explore the effects feather degrading bacteria has on birds, and in which birds this occurrence is more common. Even though more information has been collected in regard to the bacteria, studies remain ongoing. A few interesting facts have been discovered so far.

The feather degrading bacteria seems to target brightly colored birds more than those with dull plumage. To investigate this fact, a group of scientists chose a large colony of Eastern Bluebirds living in Virginia as test subjects, studying the population as a whole and noting the differences of the bacteria found in the male and female birds. Not only does this bacteria influence the coloring of the birds, but their general health as well.

It is now known that most wild birds carry feather degrading bacteria and some birds are even host to more than one bacteria species. The exact impact the bacteria has on their feathered hosts is still unclear, but they are not found to be in the majority. Almost all the birds in the study were found to have the bacteria, which hydrolyses the protein beta-keratin. It had been found that melanin pigmented feathers are resistant to feather degrading bacteria and that the oils used by birds to preen can also halt the growth of the bacteria. These traits confirm that defenses against these bacteria can be built and it is therefore suggested that the bacteria could have an influence on the evolution of birds. It was also found that the bacteria had a greater impact on the female birds than on their male counterparts. The bacteria seems to dull the coloring of the feathers, and scientists believe that the difference in bacteria between male and female birds could be influenced by the routines followed by each sex, and the areas they travel in. It is, however, mere speculation as scientists are still trying to confirm if the daily routine of males and females could play a role in the bacteria occurrences. Alex Gunderson, from Duke University in North Carolina commented, “If bacteria detrimentally influence feather coloration, they may place selective pressure on birds to evolve defenses against them.”


2 Responses to “Feather Degrading Bacteria Studied”
  1. A strain of Kocuria rosea with keratinolytic activity was studied. In batch culture, the optimum temperature for feather degradation, bacterial growth and protease secretion was at 40 °C. A specific growth rate of 0.17 h−1 was attained in basal medium with feathers as fermentation substrate. Under these conditions, after 36 h of incubation, biomass and caseinolytic activity reached 3.2 g/l and 0.15 U/ml, respectively. Extracellular protease secretion was associated with the exponential growth phase. In batch fermentation, feather degradation up to 51% in 72 h was obtained with a conversion yield in biomass of 0.32 g/g. No organic acids were detected in the fermentation broth in significant amount.

  2. Welma Herm says:

    I was wondering what will make a bird to pick their feather’s on their belly’s or under their arms? Is it stress, lack of nutrition?

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