Parrot Feathers With Bright Pigments Are More Vulnerable to Bacteria

A new Princeton-led study finds that parrot feathers with vibrant psittacofulvin pigments are more susceptible to bacterial degradation than duller feathers, overturning previous assumptions about the pigments' protective role. The research was published in the Journal of Experimental Biology. The team tested thousands of feathers from closely related parrot species against Bacillus licheniformis bacteria. Red, orange, yellow, and green feathers containing psittacofulvins broke down the most, while blue, white, black, and gray feathers without the pigment fared better, with black feathers degrading least due to melanin. Researchers suggest psittacofulvins may destabilize feather keratin, making it vulnerable to bacterial enzymes, yet evolutionary pressures favoring bright colors outweigh this cost. The pigments might also protect against other microbes, and whether bacteria threaten wild feathers remains an open question for future study.