Greater Sage-Grouse Brood Responses to Livestock Grazing in Sagebrush Rangelands

The distribution and abundance of the greater sage-grouse (Centrocercus urophasianus; sage-grouse) have declined in the last 60 years. Range contractions and population declines have been attributed to loss and fragmentation of their sagebrush (Artemisia spp.) habitats. Grazing by livestock remains the predominant anthropogenic land-use across sagebrush ecosystems in North America, occurring on 87% of remaining sage-grouse habitat. Most of the peer-reviewed literature reports the potential for negative impacts of sagebrush reduction treatments, to increase livestock forage, on sage-grouse habitat. However, few studies have linked livestock grazing at the landscape level to vital rates (e.g., nest initiation rates, nest success, brood movements, and brood success) for ground-nesting birds such as sage-grouse. We analyzed brood habitat selection of sage-grouse in response to vegetation dynamics and, where possible (DLL), in interaction with livestock grazing to determine whether the relationship between sage-grouse and cattle is competitive or facilitative. This research adds new information to the literature pertaining to the knowledge gap between livestock grazing and whether it is facilitative or competitive with brooding sage-grouse. Our results suggest that the relationship between livestock and sage-grouse might be competitive on the short term but facilitative over longer time scales. These findings indicate that deferred-rest rotational grazing practices may allow for spatio-temporal segregation, enhancing the capacity for sage-grouse to optimize the exploitation of available forage while avoiding direct contact with livestock. Further, our results suggest that livestock grazing could have carry-over effects on vegetation dynamics that may benefit sage-grouse in subsequent seasons, although we did not test this directly; more research is needed to understand the effects of livestock grazing across multiple growing seasons