Effects of predation and hunting on adult sage grouse Centrocercus urophasianus in Idaho

Abstract

Although sage grouse Centrocercus urophasianus have declined throughout their range in North America, little is known about annual mortality patterns of this species. Thus, we summarize a long-term data set on timing and causes of mortality of sage grouse. Predation was the most common cause of death for radio-marked sage grouse. For adult males, 83% of deaths were attributed to predation and 15% to hunting. However, for adult females, 52% of deaths were caused by predation while 42% were attributed to hunting. We rejected the hypothesis that type of mortality (predation vs hunting) was independent of gender of sage grouse. For males, 70% of deaths occurred during spring and summer (March-August) and 28% occurred in September-October. For females, 52% of mortalities occurred during spring and summer and 46% occurred in September-October. We rejected the hypothesis that time of death is independent of the gender of sage grouse. In six of 15 years (40%), harvest rates for adult females may have exceeded 10% while this rate was only exceeded in two of 15 years (13%) for adult males.