Gunnison sage-grouse are significantly smaller than greater sage-grouse in size of culmen, carpel, and tarsus, and they weigh approximately 1/3 less (Hupp and Braun 1991, Young et al. 2000). The two species also exhibit genetic differences (Kahn et al. 1999, Oyler-McCance et al. 1999). Additionally, Gunnison sage-grouse males have more elaborate head plumes than do greater sage-grouse males, and they have broader white barring on the tail feathers (Young et al. 2000). The two species also differ in male display behavior; for example, the Gunnison sage-grouse display ends with a tail-shaking motion of the raised tail (absent in greater sage-grouse) (Barber 1991;Young et al. 1994, 2000).