Issue link: https://read.dmtmag.com/i/35322
In addition to the general-reference datasets Bighorn Sheep (inset) use a Highway 93 wildlife overpass. Overpass locations were determined by analyzing GPS tracking data and on-the-ground assessments. available in the viewer are various stressor models that represent modeled threats to statewide wildlife populations—from urban and rural growth to grazing and aquatic invasive species. The viewer is intended to be a starting point for identifying areas with the least potential for wildlife-related conflict early in the planning process. Detailed special-status species- occurrence reports can be obtained through AGFD’s Online Environmental Review Tool. Overpasses Keep Wildlife Safe AGFD has long recognized a need to place wildlife crossing structures in meaningful areas. For example, decreasing numbers of Desert Bighorn Sheep around the area of U.S. Highway 93 from the Hoover Dam southward led researchers to look at the movement of sheep along the highway and come up with unique solutions to increase permeability for these animals. U.S. Highway 93 cuts through several mountain ranges, and as the sheep try to cross from one side to the other, they’re faced with an increased likeli- hood of vehicle collisions. Because traditional crossing structures in the form of underpasses wouldn’t have been used by this species due to their preference to be high on ridges, data from collared sheep tracked with GPS telemetry and field data were analyzed to determine the best locations for three new wildlife overpasses built during the highway’s recent widening—the first of their kind in Arizona. This research and overpass construction was funded by Arizona Department of Transportation and the U.S. Department of Transportation’s Federal Highways Administration, and the overpasses were completed in November 2010. 16 GEO W ORLD / JUL Y 2O11 Expert-Defined Wildlife Corridors Although areas of conservation potential have been identified through SHCG, the corridors connecting those areas have yet to be comprehensively delin- eated, and wildlife depend on connected landscapes to meet daily and seasonal needs. AGFD is continuing a partnership with several state, federal, university and nongovernmental organiza- tions called the Arizona Wildlife Linkages Workgroup (AWLW), originally formed in 2004. The 2006 Arizona’s Wildlife Linkages Assessment was created using stakeholder input obtained at statewide information- gathering meetings. The AWLW is working to further this effort by gather- ing more detailed expert knowledge from hydrologists, transportation planners, wildlife biologists, private landowners, and many others through the identifica- tion of current and potential linkages zones as well as present and future threats to and opportunities for conservation. This stakeholder and expert information will be combined with research data and GIS modeling to determine individual habitat blocks and the linkages connecting them. Limitations remain with the county approach: the scale of digitization, potential gaps in stakeholder representation for particular areas, and inherent data ambiguity. Some of this can be addressed through styled cartography of end products, but hard borders are difficult to overcome when used within a GIS. Planners often feel that their project is well-sited if it falls outside of a linkage, but they may not consider the habitat blocks being connected. An implemented linkage is of little use if the blocks being connected are lost to development. Fine-Scale Wildlife Corridors An ultimate goal of corridor analysis is to provide implementable recommendations. AGFD contracted with Northern Arizona University researchers to refine a high-priority subset of the linkages identified in the 2006 report, resulting in 16 reports with Planned Conservation