A new study of barn swallows has shed fascinating light on the link between appearance and the levels of sexual hormones in their bodies. Scientists have long noted that male swallows with deeper red throats attract more females and have higher levels of testosterone. Conventional wisdom assumed that swallows born with more testosterone had deeper throats and thus attracted more females. Turns out, however, that this is only partially true.

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Who’s the private dick who’s the sex machine with all the chicks?….Artificially painted barn swallow! Awwwwwww yeah.

University of Colorado, Boulder, ecologist Rebecca Safran wanted to see what would happen if she painted deep red throats on male swallows who previously did not have them. The result was somewhat staggering: Not only did the…

newly painted males attract more females and make other males jealous, but their bodies also produced significantly higher levels of testosterone almost immediately. It appears that the other birds’ behavior toward the newly painted males led to their testosterone levels naturally increasing. One theory is that male barn swallows are more aggressive to these dark and handsome suitors causing the testosterone levels to increase. Alternatively, the increased attention from female swallows may cause the increase. It is also possible that simply lookin’ good increased the swallows’ confidence.

Kevin McGraw of Arizona State University’s School of Life Sciences who also worked on the study told U.S. News and World Report, “The traditional view is that internal processes of birds determine their external features–in other words, physiology forms the feathers. But our results indicate that a perceived change in the color of an animal can affect directly its internal physiological state. A barn swallow’s hormonal profile is influenced by its outward appearance.”

Have you ever been dressed to the nines and walked by a hipster with an old t-shirt and ripped jeans on and just instinctively known that you could beat his ass if you wanted to? I don’t think this relates to the whole swallow thing. I just wanted to know if that’s ever happened to you. It happens to me like every single day in San Francisco.


  1. #1 Becca
    June 11, 2008

    That is an awesome experiment!

    Is the testosterone tied to mating, or is simply *attracting* the females enough?

  2. #2 Ian
    June 12, 2008

    Nice blog. Another feather in your cap….

  3. #3 Size
    June 12, 2008

    That last comment made me LOL, which got me strange looks from coworkers. Thanks a lot, Benny.

    Seriously, though. Painting birds? Sounds like Zoology is a lot more fun than I previously thought.

  4. #4 themadlolscientist
    June 12, 2008

    How d’ya like them apples, Jerzy Kosinski?

  5. #5 Liesele
    June 13, 2008

    So you’re saying all males are birdbrains?

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