2017-10-05_PERMIT FILE - M2017049 (36)

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Potential Mexican Spotted Owl Habitat and Use for the Hitch Rack Ranch Project Methods A habitat model to identify potential breeding habitat for MSOs was developed using Geographic Information Systems(GIS) as a tool for analysis. The study area consisted an area 3 miles of the Project area (including the Project area). The model area also was bounded by Colorado State Highway 115 to the south and east(Figure 1). The designated Little Fountain Creek Protected Activity, located approximately 1.6 miles north of the Project area, was not evaluated in this study as it is a known MSO Protected Activity Center(PAC). A total of three 7.5-minute quadrangles defined the habitat model boundary (study area) including Mount Big Chief, Mount Pittsburg, and Cheyenne Mountain quadrangles. Three key habitat features for breeding MSO habitat in Colorado were identified: steep and narrow canyons, mixed conifer forest, and elevations ranging from 6,500 to 8,500 feet amsl. GIS analysis was performed using ArcGIS 3-D Analyst and Spatial Analyst to develop a model for MSO breeding habitat using the following procedure. Step 1 — Data Input Assembly Inputs or database information used in developing this model were gathered and assembled. These inputs included: • Hitch Rack Ranch AutoCAD files to define the study area; • USA Topo Maps in ArcGIS Online; • World Imagery in ArcGIS Online; • Scalable attributed stream networks from the U.S. Geological Survey(USGS); • Scalable Southwest Regional Gap Analysis Project(GAP) -vegetation ReGAP data; and • Digital Elevation Models at 10-meter resolution. A Digital Elevation Model (DEM) consists of an array of elevations for ground positions at regularly spaced intervals. Figure 2 is an example of a DEM in the project area. Ten-meter resolution DEMs were downloaded from the USGS DEM website. Ten-meter resolution DEMs were available for the 1-degree x 1-degree region of the study area. The DEMs consist of a regular array of elevations referenced horizontally on the projected coordinate system of the Universal Transverse Mercator System, zone 13, 1927 datum. Elevation values are expressed as meters relative to mean sea level. Step 2—Creation of a Triangulated Irregular Network The DEM was used to generate a triangulated irregular network (TIN). A TIN is a tessellation (the method used to represent three dimensional objects as a collection of triangles) of space by triangular facets. This surface is partitioned into non-overlapping triangles. As such, attribute and geometry information is stored for the points, lines, and faces that comprise each triangle. TINS are a precise structure for modeling slopes of continuous surfaces using a vector data model. Figure 3 is an example of a TIN within the project area, where the smaller triangles represent areas of greatest slope. The TIN can then be symbolized to display a landscape relief background (Figure 4). Step 3—Slope Categorization Steep canyons characterize MSO habitat in Colorado (Johnson 1997). To identify areas with the greatest habitat potential, slopes were partitioned into four categories from the TIN data as follows: 1) less than 10-degree slope; 2) 10-to 20-degree slope; 3) 20-to 40-degree slope; and 4) 40-to 70-degree slope. Degree slope is the angle of the vertical rise over the horizontal distance expressed as a degree. For example, a slope where the elevation increases 100 feet for every 100-foot horizontal distance has a 45-degree slope. Figure 5 is an example of a TIN where slope categories have been assigned different colors, with darker colors representing areas of greater slope. It is an assumption of this model that September 2017 3