Unhapiness of Blue Birds: Losing their Sparkle

Brightly coloured birds can become infected with bacteria that eat the coating on their feathers. That in turn can affect the health of the birds and dull their plumage.

The discovery comes from a study that found that 99% of all Eastern US bluebirds srveyed, were infected with feather-degrading bacteria. Such bacteria were first discovered a decade ago, but the latest research is the best evidence yet that the bugs affect the colour and general health of the birds.

New to Bird studies

"Feather-degrading bacteria are relatively new to ornithologists," says Alex Gunderson of Duke University in Durham, North Carolina, US. "The first report of their occurrence on wild birds was published only ten years ago."

Since then, scientists have found that most species of wild bird probably harbour some feather-degrading bacteria in their plumage, sometimes of more than one species.

Impacts on their hosts

Feather-degrading bacteria work by hydrolysing the protein beta-keratin, which constitutes over 90% of a feather's mass but these bugs are usually found in a minority of birds sampled, and it has not been clear what impact they have on their hosts.

So Gunderson and colleagues Mark Forsyth and John Swaddle of the College of William and Mary in Williamsburg, Virginia, US surveyed a population of Eastern bluebirds (Sialia sialis) living in Virginia.

They found that 99% of all the birds surveyed carried feather-eating bugs. The full report can be found in the Journal of Avian Biology.