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14094 Federal Register / Vol. 62. No. 57 / Tuesday. March 25, 1997 / Proposed Rules i
<br /> Results from limited genetic analysis over drier uplands.Whitaker(1972) opportunities. Five nests were located
<br /> of Z. hudsonius from Minnesota and concluded that Z. hudsonius avoids the in dense vegetation (Harrington et al.
<br /> Indiana, presumed Preble's meadow sparse vegetation that is generally 1995). Litter is used to construct nests.
<br /> jumping mouse from the Department of associated with low moisture habitats. which are occupied during the Preble's
<br /> Energy's Rocky Flats Environmental Fitzgerald et al. (1994) described Z. meadow jumping mouse's active season.
<br /> Technology Site (Rocky Flats) in hudsonius as most common in lush Based on a single underground
<br /> Jefferson County, Colorado, and Z. vegetation along watercourses or in hibernaculum, located through use of
<br /> princeps from Colorado, provided clear herbaceous understories in wooded telemetry, upland habitats may be
<br /> evidence that the Rocky Flats mice were areas. Some authors (Tester et al. 1993) preferred for hibernation by Preble's
<br /> of the species Z. hudsonius. However, have suggested that proximity to water (Fred Harrington, Pawnee Natural
<br /> the analysis did not provide a means of may be the most important factor History Society, pers. comm. 1995).
<br /> separating subspecies of Z. hudsonius influencing habitat selection and Ryon (1995) reported that four of five
<br /> (Bruce Wunder, Colorado State utilization by Z. hudsonius. recent Preble's meadow jumping mouse
<br /> University, pers.comm. 1996). Under a Recent research on the Preble's capture sites he evaluated in Colorado
<br /> cost-sharing agreement with the U.S. meadow jumping mouse has focused had five structural habitat components:
<br /> Fish and Wildlife Service (Service), the mostly on current status: however,some trees, tall shrubs,short shrubs,
<br /> Colorado Division of Wildlife supported aspects of life history, behavior,and herbaceous vegetation,and ground
<br /> genetic studies of Preble's trapped in habitat utilization have been cover.The fifth site had few trees. In
<br /> Colorado during the 1996 field season. documented. In general, results of contrast, historic capture sites where
<br /> Tissue samples from Preble's trapped in recent investigations have not been Ryon failed to capture Preble's generally
<br /> Colorado are being assessed, through documented in peer-reviewed scientific lacked one or more of these
<br /> mitochondria)DNA analysis,and will literature. Data have been gathered by components. Harrington (1995) captured
<br /> be compared to available reference researchers at Rocky Flats on the timing Preble's in riparian shrubland
<br /> samples from Z. hudsonius from other of the initial breeding period and time dominated by Salix exigua along East
<br /> areas. While mitochondrial DNA of hibernation (PTI Environmental Plum Creek, Douglas County,Colorado.
<br /> analysis is an accepted technique for Services 1996).The month of May Preble's was captured along Monument
<br /> establishing taxonomic relationships, it marks the beginning of the active period Creek within the U.S. Air Force
<br /> is uncertain whether these studies will for Preble's.with May 5 the earliest Academy lands in Colorado Springs, El
<br /> produce conclusive results regarding the capture date at Rocky Flats. Breeding Paso County, Colorado, primarily in
<br /> genetic differences between Preble's and probably occurs soon after emergence. densely vegetated riparian communities
<br /> other recognized subspecies of Z. Adults begin hibernation in early where Salix spp., Symphoricarpos
<br /> hudsonius. Results of these studies will September.while juveniles enter occidentalis, Populus angustifolia.
<br /> be available in 1997. hibernation from mid-September to late (narrow-leaf cottonwood), and thick
<br /> Under section 15.3 of the Act, the October. grass understory were dominant (Corn
<br /> term"species" is defined to include At Rocky Flats, the Preble's meadow et al. 1995).Garber (1995) characterized
<br /> recognized subspecies. Therefore, jumping mouse appears to be primarily capture sites along Lodgepole Creek,
<br /> throughout the remainder of this dependent on riparian corridors along Albany County.Wyoming as moist areas
<br /> document. Preble's meadow jumping creeks that are dominated by the shrubs near beaver ponds with dense sedges
<br /> mouse (Z. h.preblei) is treated, in the Salix exigua (coyote willow) or and Salixsp. Ryon (1995) suggested that
<br /> context of the Act, as a ..species." Amorpha fruticosa (leadplant), and are where Preble's occupies habitat along
<br /> Though the Preble's meadow jumping in proximity to mesic grasslands intermittent streams, adjacent wet
<br /> mouse has not been studied as dominated by Andropyron smithii meadows and seeps may be important
<br /> intensively as Z. hudsonius has been (western wheatgrass) and Poa pratensis habitats in dry periods.
<br /> studied elsewhere, it is believed to be (Kentucky bluegrass) (Bakeman, Deans Based on recent survey data. Preble's
<br /> similar to other subspecies of Z. and Ryon, EG&G, in litt. 1995). Field are most frequently encountered along
<br /> hudsonius in patterns of diet. behavior, studies at Rocky Flats led to the riparian corridors of small intermittent
<br /> breeding and habitat utilization. In conclusion that Preble's is typically and perennial streams,where low Salix
<br /> general. Z. hudsonius subsists on seeds, found in or near complex riparian sp. and other dense shrubs are found
<br /> small fruits, fungi,and insects, and communities with multi-strata with lush ground cover (grasses, forbs,
<br /> hibernates from October to May woodland and herbaceous species etc.). Recent captures that were
<br /> (Fitzgerald et al. 1994,Whitaker 1972). (Harrington et al. 1996). Capture exceptions to the above described
<br /> It is adapted for digging, creates nests of locations were typically humid with habitat, include individuals found along
<br /> grasses, leaves.and woody material high litter content. In a spring 1996 a small irrigation ditch and in a mesic
<br /> several centimeters below the ground, study at Rocky Flats, all captures were grassy field on City of Boulder Open
<br /> and is primarily nocturnal or within 25 meters (m) (82 feet (ft)) of Space land (Clint Miller, City of
<br /> crepuscular,but can be observed during streams,with 48 percent of captures Boulder, in litt. 1996).
<br /> daylight. During the breeding season within 5 in (16 ft) of streams (PTI Preble's meadow jumping mouse may
<br /> (June to mid-August), females typically Environmental Services 1996). In the never have been widespread in
<br /> have two to three litters (Fitzgerald et al. same study, 90 percent of captures historical times.Armstrong (1972)
<br /> 1994). occurred within 5 in (16 ft)of canopy described it as poorly known in
<br /> Krutzsch (1954). Quimby (1951). and edge consisting of Salix exigua, Colorado and apparently nowhere
<br /> Armstrong (1972) agree that across its Symphoricarpos occidentalis(western abundant.The historical range of
<br /> range. Z. hudsonius occurs mostly in snowberry). Prunus americana. (choke Preble's may represent a relic of a much
<br /> low undergrowth consisting of grasses, cherry).and other species.Margins of larger range,occupied when the climate
<br /> forbs,or both. in open wet meadows artificial ponds at Rocky Flats are was cooler and damper (Fitzgerald et al.
<br /> and riparian corridors,or where tall thought to be important foraging sites 1994). Nevertheless,the apparent
<br /> shrubs and low trees provide adequate (Harrington et al. 1996). extirpation of Preble's from historically
<br /> cover.In addition, Z. hudsonius prefers Most successful capture sites at Rocky occupied sites in Colorado and
<br /> lowlands with medium to high moisture Flats presented burrowing or nesting Wyoming,and the difficulties in finding
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