Restoration of bighorn sheep metapopulations in and near western national parks
Bighorn sheep ( Ovis canadensis ) once were ubiquitous in large areas, including lands now contained in the national parks of the Intermountain and Colorado Plateau regions of the United States. Due to catastrophic declines in the late 1800s and early 1900s, most extant populations now occur as small, isolated groups with a highly fragmented distribution. Three different subspecies of bighorn sheep were extirpated from 14 of 18 areas that are now managed by the National Park Service. We describe an eight-year plan to restore bighorn sheep to currently suitable historic habitats in the national parks within a six-state intermountain region of the western United States, 1991–1998. A seven-point program was recommended for each park unit that included: (1) survey the existing populations; (2) conduct a GIS-based habitat assessment to identify suitable habitat; (3) convene scientific advisory panels to review results of habitat assessment; (4) convene interagency panels to discuss metapopulation management and to plan the restoration(s); (5) draft interagency restoration and management plans; (6) conduct translocation(s); and (7) monitor the populations. We evaluated 38,781 km 2 of area; 32% (12,329 km 2 ) was potential habitat for bighorn sheep. The scientific advisory panels and the GIS modeling recommended bighorn restoration on 73 sites within these areas. By 1996, 36 of these sites (2,647 km 2 or 22% of the entire suitable area) were inhabited by bighorn sheep. By 1999, the translocated animals increased 25%, and restoration efforts will continue in many of the remaining sites.