For most animals, scent is the instant messenger of choice for quickly exchanging personal profiles. Scientists, however, have long dismissed birds as odor-eschewing Luddites that don’t take advantage of scent-based communications. In a first-of-its-kind study, however, a Michigan State University researcher has demonstrated that birds do indeed communicate via scents, and that odor reliably predicts their reproductive success. The study was published online on August 29, 2013 in Animal Behaviour and focuses on volatile compounds in avian preen secretions. Birds’ preen glands are located near their tails. Using their beaks, birds extract oil from the glands and rub it on their feathers and legs. Historically, this activity was thought to simply bolster the strength of feathers. Dr. Danielle Whittaker, managing director of MSU’s BEACON Center for the Study of Evolution in Action, and her research team, however, have shown that it plays a key role in signaling reproductive health. “This study shows a strong connection between the way birds smell near the beginning of the breeding season – when birds are choosing mates – and their reproductive success for the entire season,” she said. “Simply put, males that smell more ‘male-like’ and females that smell more ‘female-like’ have higher genetic reproductive success.” The long-held assumption was that birds’ preferred methods of communication and mate selection were visual and acoustic cues. Studying dark-eyed juncos (see image courtesy of Nicole Gerlach), Dr. Whittaker’s team compared which were more effective – chemical signals or size and attractive plumage. The results showed that individual bird odor correlated with reproduction success while size and plumage were less reliable.
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