David Tipling / Two male Greater prairie chickens (Tympanuchus cupido) fighting on lekking ground in the Sandhills, Nebraska. USA, April

Gerrit Vyn / Aggressive encounter between two male Greater Prairie-Chickens (Tympanachus cupido) on a lek. During these aggressive encounters, males lower their pinnae feathers, deflate their air sacs, leap into t...

Gerrit Vyn / Aggressive encounter between two male Greater Prairie-Chickens (Tympanachus cupido) on a lek. During these aggressive encounters, males lower their pinnae feathers, deflate their air sacs, leap into t...

Rolf Nussbaumer / Lesser Prairie-Chicken {Tympanuchus pallidicinctus} males fighting, Panhandle, Texas, USA, February

Shattil & Rozinski / Lesser prairie chicken {Tympanuchus pallidicintus} males fighting at lek, Colorado, USA

Tim Fitzharris / Greater Prairie Chicken (Tympanuchus cupido) male in courtship display, Eagle Lake, Texas

Cheryl-Samantha Owen / Greater prairie chickens (Tympanuchus cupido) Bob Price's Ranch, Garfield County, Nebraska, USA, October.

David Tipling / Greater Prairie-Chicken (Tympanchus cupido) displaying on lekking ground, Sandhills, Nebraska, USA, April.

Bob Steele / Lesser Prairie Chicken (Tympanuchus pallidicinctus) males displaying at lek, Roosevelt County, New Mexico

Bob Steele / Lesser Prairie Chicken (Tympanuchus pallidicinctus) males displaying at lek, Roosevelt County, New Mexico

Bob Steele / Lesser Prairie Chicken (Tympanuchus pallidicinctus) male, Roosevelt County, New Mexico

Bob Steele / Lesser Prairie Chicken (Tympanuchus pallidicinctus), Roosevelt County, New Mexico