Smells Like ‘Preen’ Spirit

Does your sweetheart smell sexy? It might not be only their looks that make them hot… or not.

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Scent is one of the most basic ways animals exchange information, but many animals are thought to primarily use other modes of communication, like acoustic or visual signals, to indicate their status and quality as a mate. Birds have been dismissed in this way, however, from a first-of-its-kind study, we now have evidence that birds not only communicate via scent, but also use it to evaluate mates.

Birds’ scent, or preen, glands are located near their tails, and using their beaks, birds extract this gland oil and rub it along their feathers and legs. Although it was thought that rubbing the oil just bolstered the strength of feathers, this new research shows that this scent also signals 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,” lead author Danielle Whitaker said. It appears that the more ‘male’ a male’s scent, and the more ‘female’ a female’s scent, the more offspring those birds will have.

Because birds were assumed to communicate and select mates primarily through visual and acoustic cues, the researchers studied a species of bird, dark-eyed juncos, to compare which were more effective– chemical scent signals or size and attractiveness of feathers. Image

Although size and feather attractiveness were useful in predicting reproductive success, the study’s results showed that individual bird odor was better! The study also revealed that females were making multiple decisions based on how their potential mates smelled.

“Based on odor, females seemed to be not only choosing with which males to mate, but many times they also were selecting different males to raise their nestlings,” Whittaker said. “Interestingly enough, the cuckolded males had higher levels of a ‘female-like’ odor.” From the data, it appears that odors may also serve as beacons for hormone levels, current condition and overall health, and genetic background of a potential mate.

The study, authored by Danielle Whittaker, managing director of MSU’s BEACON Center for the Study of Evolution in Action, and her collaborators at Indiana University, appears in the current issue of Animal Behaviour. Read more here: Whittaker, D.J., Gerlach, N.M., Soini, H.A., Novotny, N.M, and Ketterson E. D. (2013). “Bird Odor Predicts Reproductive Success”, Animal Behaviour 86(4): 697-703.

Photos courtesy of Danielle Whittaker and Nicole Gerlach.

[Repost from my work with the BEACON Buzz, October 2013]

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