1997-06-13_REPORT - M1981302 (18)

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livestock grazing has occurred since the mid-1970s on the majority of the buffer area around the station. Some of this land is potential Z. h.preblei habitat. Dr. Bruce Wunder, University of Colorado, conducted live- trapping during the 1970s on station land as part of an Ecological Monitoring study of the location, and captured three individuals over an eight-year period. No proactive management has occurred on the site to monitor or preserve habitat for this subspecies. 3. City of Boulder Open Space: Tracy Collins parcel-The Tracy Collins parcel, which contains part of the Coal Creek riparian area, has been administered by the City of Boulder Open Space Department since 1984 (Mark Gershman pers. comm.). The area consists of 146 acres that are leased for livestock grazing. Public access is also allowed on the area for recreational purposes, but no trails occur in the specific area of capture, and recreational use is very low. The specific area is bordered by Colorado State Highways 93 and 128 to the west, north and east, and by other Open Space lands to the south. The area is surrounded by Open Space lands for a distance ranging from 1.5 to 4.5 miles. 4. City of Boulder Open Space: VanVleet parcel- The VanVleet parcel has been administered by the City of Boulder Open Space Department since 1978 (Mark Gershman pers. comm.). The parcel consists of 771 acres, and is bordered to the north by the Burke parcels and to the south by other Open Space lands. The specific location of capture is bounded by Open Space lands for close to 1.0 mile in any direction. The parcel is leased for agricultural and grazing purposes. Public access is also allowed for recreational activities, although dogs are prohibited on the VanVleet parcel itself. A heavily utilized walking/hiking trail exists through the VanVleet parcel, very close to the location of capture. B. Performance under changed conditions- There is a paucity of information available concerning the status of populations of Z. h. preblei over time or under • changing conditions. One example, however, may include the history of capture data from Fort St. Vrain. Summer grazing began at Fort St. Vrain sometime in the mid-1970s, at the latest- There were single captures in 1972, 1976 and 1977, the first capture being prior to, and the latter two captures during heavy grazing. However, there was no capture in 1992, which may indicate the negative effect of long-term, heavy grazing of livestock on the vegetational habitat of Z. h. preblei. Winter grazing has been allowed on the VanVleet parcel (location of most recent capture) since 1978. Winter grazing would not be expected to directly impact hibernating jumping mice, but might impact habitat structure. Armstrong (1972) indicated that due to the dependence of this subspecies on dense vegetation in moist lowlands, irrigation should have an influence, both historically and currently, on the locations of occurrence of this subspecies. C. Current management policies and actions 1. Rocky Flats Plant- Currently, the Rocky Flats Plant maintains its security fence, as the plant is currently conducting environmental restoration and waste management. The plant is planning to be fully decommissioned and decontaminated sometime in the future. Land management of the buffer zone is not a proactive process. However, there is discussion concerning designating the Rock Creek area, located FaW S,m.Sauey Piw.Ecs.lac M. JI .o ' 1