DISTRIBUTION OF SAGE-GROUSE IN NORTH AMERICA

We revised distribution maps of potential presettlement habitat and current populations for Greater Sage-Grouse (Centrocercus urophasianus) and Gunnison Sage- Grouse (C. minimus )i n North America. The revised map of potential presettlement habitat included some areas omitted from previously published maps such as the San Luis Valley of Colorado and Jackson area of Wyoming. Areas excluded from the revised maps were those dominated by barren, alpine, and forest habitats. The resulting presettlement distri bution of potential habitat for Greater Sage-Grouse encompassed 1 200 483 km 2, with the species' current range 668 412 km 2 . The distribution of potential Gunnison Sage-Grouse habitat encompassed 46 521 km 2 , with the current range 4787 km 2 . The dramatic differences between the potential presettlement and current distributions appear related to habitat alter ation and degradation, including the adverse effects of cultivation, fragmentation, reduction of sagebrush and native herbaceous cover, development, introduction and expansion of in vasive plant species, encroachment by trees, and issues related to livestock grazing.