Dr. Boyd is a member of the Oregon Sage-grouse planning team, and organized a diverse group of authors in developing and invited synthesis paper on the ecology and management of sage-grouse for the Journal of Range Management. He currently serves on the technical review panel for the Natural Resource Conservation Service’s “Sage-grouse Restoration Project”.
Livestock grazing has been indirectly related to sage-grouse declines in the western United States and southern Canada; however, there is a lack of scientific research that directly relates the two. We used grazing trials conducted in the summer of 2003 and 2004 to determine the level of utilization at which cattle begin to access herbaceous vegetation adjacent to and under the canopy of sagebrush. This vegetation is thought to provide important screening cover for nesting sage-grouse, providing a degree of protection from potential nest predators. Four pastures 15 acre pastures were fenced in a Wyoming big sagebrush community and each stocked with 3 to 4 yearling heifers. Within each pasture 30 sagebrush plants were randomly located and a randomly selected perennial grass was permanently marked under the canopy of each sagebrush and a second marked in the interspace between shrubs. Visual obstruction for a potential nest site was measured using a modified Robel pole to document changes in screening cover with increasing herbaceous utilization. Grass plants were checked every second day and given a grazed or ungrazed score. Changes in standing crop and utilization (by weight) were assessed weekly by clipping 20 random 1-m² plots in each pasture. Grazing of under-canopy plants was negligible at light to moderate levels of utilization (e.g. < 10% of under canopy plants were grazed at 30% pasture utilization). At utilization levels >30% by weight, under canopy plants were used with increasing frequency. There was no statistical effect on visual obscurity with consumption of forage for this environment. Overall, our data suggest that sagebrush constituted the bulk of screening cover at this site and that utilization of understory grasses will be minimal with light grazing.
Crawford, J.A., R.A. Olson, N.E. West, J.C. Mosley, M.A. Schroeder, T.D. Whitson, R.F. Miller, M.A. Gregg, and C.S. Boyd. 2004. Ecology and management of sage-grouse and sage-grouse habitat. Journal of Range Management 57:2-19.
France, K.A. 2005. Interspace/Under-canopy Foraging Patterns of Beef Cattle in Sagebrush Communities: Implications to Sage-grouse Nesting Habitat. M.S. Thesis, Oregon State University, Corvallis.
If you are interested in this study, contact Chad Boyd.