Alpha Bison: The Quieter Bellow Wins The Females

Two male bison fight. i i

hide captionWhen a female runs through a group of males, the males often respond by bellowing and fighting each other in what Wyman calls a "bison storm."

iStockphoto.com
Two male bison fight.

When a female runs through a group of males, the males often respond by bellowing and fighting each other in what Wyman calls a "bison storm."

iStockphoto.com
Scientist Megan Wyman in a field with bison. i i

hide captionMegan Wyman gets close, but not too personal, with bison in Nebraska. Wyman records bison vocalizations to find out if dominant males sound different from other males in the herd.

Courtesy of Megan Wyman
Scientist Megan Wyman in a field with bison.

Megan Wyman gets close, but not too personal, with bison in Nebraska. Wyman records bison vocalizations to find out if dominant males sound different from other males in the herd.

Courtesy of Megan Wyman
A male bison guards a female. i i

hide captionA male bison "tends" a female to keep other males away during the mating season.

Megan Wyman
A male bison guards a female.

A male bison "tends" a female to keep other males away during the mating season.

Megan Wyman

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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