Birds use bacteria to produce odour, and if these microbes are altered, it could negatively impact their ability to communicate with others of its species or find a mate, according to a study. The researchers, including those from Michigan State University in the US, discovered that scents emitted by songbirds are produced by certain bacteria in their preen glands which help the birds identify each other.
This is the first study proving that bacteria associated with birds produced volatile compounds causally related to avian behaviour, the researchers said. The study, published in the Journal of Experimental Biology, noted that if the odour producing bacteria are removed or changed, the bird may fail to express the correct information about its identity to others.
"Though several studies have demonstrated correlations between scent gland bacterial community structure and host animal odour profiles, none have systematically demonstrated a causal relationship," the researchers wrote in the study. The researchers said that the odours produced by birds are unique to them, and allow others of its kind to gain crucial information regarding the mating process.
"This is the same process as in humans. We each have bacteria on our bodies that create smells like armpit odour that is unique to each person," said Danielle Whittaker, lead author of the study from Michigan State University. The study noted that birds used odours to determine the stage of reproduction process, quality, or hormonal state of a potential mate.
"Alter that bacteria and the bird could be less attractive to potential mates," Whittaker said. According to the researchers, birds behave like humans putting on deodorant or perfume when they rub their bill over the preen gland (a bilobed gland located at the back of most birds towards the base of the tail), and then apply the oil over their feathers and body.
As part of the study, Whittaker and her team injected antibiotics directly in the preen gland of dark-eyed juncos -- small grayish American sparrows common across temperate North America. The process, the study noted, changed both the bacterial communities and the bird odours.
The researchers also cultured bacteria directly from the preen oil and measured the odours produced by the bacteria alone, which they said, included the same odours present in preen oil. "Bacteria can change for a number of reasons, including from the environment, infections, hormones or social interactions," Whittaker said. She said that even in humans, personal smells are impacted by people's microbiomes.
"Take antimicrobial products for instance. They seem like a great idea for staying clean, until you realize they can negatively change your microbiome. The same thing goes for birds and other animals," Whittaker said.