The bison bull sticks out his tongue, tests the air, and bellows: a sound part that’s lion’s roar, part rolling thunder.

Clearly agitated, the bull bellows again, then begins urinating, spraying himself frenetically. He rolls in a patch of bare earth, finally rising—covered in an aromatic blend of excrement and prairie dust.

He looks around for challengers. None seem ready to take him on—this time. For the past several weeks, though, the prairie has been alive with bison bulls bluffing, sparring and head-butting their way to be the dominant male.

All that battling is tough, exhausting work for a bison bull. But new research being conducted at The Nature Conservancy’s Samuel H. Ordway Prairie Preserve suggests this fighting – and lots of it – is key to maintaining the genetic health of bison.

Studying bison interactions may help managers make better decisions on fenced preserves and ranches — where most bison roam today.

Jon Grinell, professor of biology at Gustavus Adolphus College, has been leading student research on bison at the Ordway Prairie for six years. The effort started as animal behavior research on rutting bulls, but the scientists found that bull competition could even help ensure the long-term survival of the species.