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

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Potential Mexican Spotted Owl Habitat and Use for the Hitch Rack Ranch Project (Johnson 1997). All MSO nests in Colorado were in rock caves or on ledges on vertical sheer-walled rock cliffs. No MSO nests were found in tree cavities or stick or debris platforms (Johnson 1997). Spotted owls have been described as"perch and pounce" predators (Forsman 1976) and typically are nocturnal feeders (Forsman et al. 1984; Ganey 1988), although they will opportunistically take prey during daylight hours (Forsman et al. 1984; Laymon 1991). In the Project region, studies found that woodrats (Neotoma spp.) comprised 41 percent of the MSO diet and accounted for 75 percent of the total biomass consumed. Voles (Microtus spp.) and deer mice(Peromyscus spp.) each comprised 26 percent of the MSO diet and accounted for 20 percent of the biomass consumed (Johnson 1997). Based on this information, woodrats are the most important prey species of MSOs in the Project region (and in Colorado). Because of their importance, woodrats may play a critical role in habitat selection by the owls. Woodrats within the geographical and elevational range of MSOs are closely associated with rock out- crops and boulders (Finley 1958). Thus, MSOs may occupy steep rocky canyons because of the type and amount of prey available there(Johnson 1997). Summary In summary, all MSO sites occupied deep, rocky canyons during the summer months. In many cases, MSOs occupy steep, narrow, and rocky tributary canyons of larger canyon systems. Furthermore, Colorado MSOs roost and nest in the narrowest, most sheer portions of these canyons and appear to be selecting specific areas within canyons to maximize the amount of protection from high temperatures and direct sunlight(Johnson 1997). Other factors that may affect the selection of roost and nest sites include prey abundance and avoidance of predators (e.g., golden eagles, horned owls) (Johnson 1997). Inter-Seasonal Movement and Winter Habitat Between 1992 and 1996, radio-telemetry was used to track MSOs from their summer habitats to their winter habitat sites. All radio-tagged MSOs migrated from their summer habitats consisting of narrow steep-walled rocky canyons dominated by Douglas-fir and white fir forests, to lower elevation canyons or drainages with a north-to-south orientation during late fall, winter, and early spring. Vegetation in these areas were dominated by pinyon/juniper woodlands with scattered patches of ponderosa pine. Distances traveled between summer and winter habitats ranged from 1.1 miles to 10.3 miles(mean: 4.2 miles) and elevation changes ranged from 394 feet to 1,335 feet(mean: 764 feet) (Johnson 1997). No additional radio-telemetry data on migrating owls in Colorado is known to occur. Additionally, no studies were performed regarding MSO winter habitat characteristics (including roosting and foraging) in Colorado. Habitat Use Near the Project Area No MSOs have been documented on the Project area. Occurrence data by MSOs near the Project area includes a MSO carcass, from radio-tagged owl, that was recovered on the Ranch in 1994 (E. Brekke, Bureau of Land Management(BLM), pers. comm. 1994). The MSO carcass was found in the NE%of NE%of Section 16, Township 16 South, Range 67 West(Deadman Creek), approximately 2.9 mile east of its known breeding site. This MSO was presumably overwintering in the ranch area. Necropsy results indicated that the owl died of pulmonary aspergillosis (fungal disease) and emaciation (D. Getzy, DVM, pers. comm. 1994). Other specific information on overwintering MSOs near the Project area included radio-telemetry location data and transmitters that were recovered approximately 1.5 miles from the Project area in 1994 and 1996 (Johnson 1997). Potential MSO Breeding Habitat Model Given the MSOs status as federally threatened, known distribution, and designated critical habitat in the Project region, Transit Mix desires to determine where potential MSO breeding habitat occurs relative to the Project area. Based on known occupied MSO habitat along the front range of Colorado, this habitat model was used to develop and identify potential breeding habitat within 3 miles of the Project. September 2017 2