West Mojave Plan FEIR/S - Desert Managers Group

1996). As herbaceous annuals appear in the spring, the MGS shifts to leaves, flowers, seedsand/or pollen of forbs (annual plants). Once the ephemeral forage disappears in a normal rainfallyear, the MGS resumes feeding on shrub parts until entering hibernation. If no ephemeral forageis available in a given season, the MGS subsists entirely on perennials.The Leitners have shown, through repeated observations employing consistent livetrappingmethodologies and fecal analyses, that winterfat, hopsage, and various saltbush species(genus Atriplex) are common components of the MGS diet in the northern part of its range, atCoso Hot Springs. They have demonstrated that winterfat and hopsage, in particular, comprise alarge part of the MGS’ diet during years when rainfall was below about 75 mm at their studyplots. They have hypothesized that these two plants may be critically important in allowing theMGS to attain 180 g body weight during dry years when preferentially selected annual plants areunavailable.It remains unknown, but is plausible, that these plants are equally important to the south.Dr. Anthony Recht (1977) found that MGS at Saddleback Butte in Los Angeles Countyconsumed substantial amounts of Russian thistle (Salsola tragus), which he found to have a veryhigh water content, and others have documented MGS feeding heavily on the seeds of Joshuatrees (Yucca brevifolia) (Laabs 1998). The Leitners have been very cautious to apply their Cosoresults to MGS foraging preferences elsewhere in the planning area, because their study sites arelocated within about 15 to 20 miles of the northern range boundary line. The comparisons givenbelow, however, suggest that there may be a relationship between the prevalence of these twoplants and the relative occurrence of (trappable) MGS elsewhere in the western Mojave Desert.Recent evidence suggests that winterfat and spiny hopsage may be important foragespecies well to the south of the Coso study sites. In 1998, 344 perennial vegetation transectswere surveyed both within the range to the south and in the Ord-Rodman DWMA, east of therange 24 (Map 3-16). Each transect surveyed during this “1998 survey” consisted of a ¾-mile,equilateral triangle. All perennial plant species within one meter of each transect were counted.Transect locations included:• 102 places where the MGS was previously observed (i.e., CNDDB, Debi Clark records,and 19 of 22 sites surveyed by Aardahl and Roush (1985) (the “Aardahl-Roush sites”);• 208 additional locations in “High” and “Medium” quality habitats 25 within the knownrange; and,• 34 sites in the Ord-Rodman area, located east, south, and northeast of the known range.24 Surveyors (transects given in parenthesis) included LaRue (237 transects), botanists Dave Fleitner (87), DaveSilverman (7), and R.T. Hawke (3), and by biologist Dave Roddy (10). Transects were surveyed in the spring andsummer of 1998. As indicated in the text, 34 transects were in the proposed Ord-Rodman DWMA).25 The 208 transects were systematically (rather then randomly) located at about two-mile intervals within the 1993polygons that CDFG and others identified as “High” and “Medium” quality habitats (although those designationshave since been dismissed; see U.S. Bureau of Land Management 2000).Chapter 3 3-149