Alpha Bison: The Quieter Bellow Wins The Females

Megan Wyman has earned the right to call herself a cowgirl; she's spent four summers in the Great Plains of Nebraska, much of it riding in the back of a pickup truck chasing after bison. But it's sound, not trophies, that she's after.

Wyman studies animal communication.

"I am trying to decipher exactly what a sexy, dominant bison male sounds like," she says. "More specifically, I am trying to decode bison bellows."

Wyman wants to know what acoustic qualities — frequency, duration, loudness — mark a male who is, you might say, a bon vivant with the ladies during mating season. Wyman thinks a male bison uses his bellow to defend his female(s) from other males, and also perhaps to influence the female to choose him as a mate.

Just what kind of bellow marks a good mate is still a mystery. Wyman's data suggest that "high quality" bison males bellow more quietly than "low quality" males, which is not what she expected. Wyman, a student at the University of California, Davis, published some of her findings in the November 2008 issue of the journal Animal Behavior.

Besides bellows, bison have a variety of sounds they make; sometimes it's just rapid, noisy breathing, sometimes it's like a motor revving up, and sometimes it's a low rumble. Cows and calves also communicate with each other with soft, short "tonal" calls.

This year, Wyman is headed off to Great Britain and New Zealand to record another species: red deer.

"Amazing sounds," she says. Based on her bison recordings, that's easy to believe.

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