1997-06-13_REPORT - M1981302 (16)

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We suggest that GIS analysis proceed in the following way. • coked VrM coordinates of sites where Preble's mice have been found recently(ItducllM Ryon's'historicar sites), and as marry unsuccessful sites as possible,and design and enter these coordinates into a database for uploading into the GIS; • gather the data coverages indicated above for the states of Colorado and Wyoming for the listed counties(check with Rocky Flats and City of Boulder staff for existing information), • make the mapping of riparian areas in the listed counties a high priority(suitable upland'buffer" areas can be added if needed);and • conduct analyses with Input from regulatory staff and concenhed knowledgeable scientists. VIIL General Riparian Habitat Description Typical meadow jumping mouse habit,'t is well-developed plains riparian vegetation with relatively undisturbed grassland and a water : urce in dose proximity. Dense herbaceous vegetation consisting of a variety of grasses. forbs and thick shrubs are favored. A tall shrub or tree canopy may or may not be present at a given capture location but usually occurs in patches within the riparian comdor. Grassland undisturbed by human activities, such as dense housing or gravel mining,typically surrounds this riparian vegetation complex. The majority of successful sites consist of multistoried cover but the species composing the cover vary greatly. The herbaceous understory can be primarily grasses or(orbs or a mixture of the two. Few of the sites, however, are dominated by fewer than two understory species. The tag shrub canopy at most sites is willow(several species). although scrub oak and alder occur in sites south of the Palmer Divide. In 8 Paso County, the shrubs are predominantly oak, birch and alder. Ponderosa pine is the most common tree at these higher elevations. The mouse appears to tolerate weedy or exotic spades in areas that are structurally diverse and species rich; nearly every successful site contained Canada thistle. The mouse does not appear to have an a"tavard any single piart spades but inroad fawns sites which are sLvchray diverse and provide adequate cover and food throughout its life cyde. Meadow)umping mouse habitat can also be described from a landscape perspective. A landscape desa"on of habitat must begin with iderhfification of the overall habitat matrix and thhe most eudersive and connected landscape element within the area of geographic distribution. Also vital is a discussion of patches of habitat where Preble's mice occur within this matrix The matrix of the meadow jumping mouse geographic range a mixed gasstmhds adjacent to the Colorado Front Range along the Piedmont and along Cie vase of the LararYe Mountains in Wyoming. Within this matrix are stream drainages that contain petdhea(definable area of vegetation of shnilm type or strtadsure Chet Is surrounded by a different type)of riparian vegetation. These rather mean vegetation patches are highly diverse within the geographic range and include woody,wetland,and grassland vegetation associations. DL Disturbance elements Over the past 100 years the landscape cart described n number Vlll.above,has become i creasi*urbanized as influenced by gazing.water diversions.wetland conversion,and real estate development(see below). Compton and Hugh(1993)Identified agriaullial,residential.and commercial development as habitat Impacts and suspected grazing as having a negative influence on meadow Jumping mouse habitat Ryon(19N)identified alterations to habitat at eight historic meadow jumping mouse sites. These alterations include water diversion,highway construction, gravel mining, grazing,and real estate deveiopmenL Although suitable habitat exists within this landscape unit, the anthropogenic influence is changing the unit as a whole and fragmenting and degrading riparian areas in general. 9