West Mojave Plan FEIR/S - Desert Managers Group

Regional Declines in the Four DWMAs: In comparing the earliest survey efforts withlater ones, it appears that there have been substantial declines in tortoise numbers in thenorthwest portion of the Fremont-Kramer DWMA. This area is bounded by Highway 58 to thesouth, Red Mountain to the north, Fremont Peak to the east, and the DTNA to the west. Itencompasses the three DTNA study plots and those at Fremont Peak and Fremont Valley, whereDr. Berry documented tortoise declines ranging from 93% at Fremont Peak to 72% at theFremont Valley study plot. No above-average tortoise sign polygons were identified anywherewithin this region. Although there were a few transects with above-average tortoise sign, thesewere insufficiently concentrated for the polygon criteria to be met.The analysis found above-average tortoise sign polygons to be oriented on a northeast-tosouthwestaxis, from about Fort Irwin to the northeast to areas south-southeast of Edwards AirForce Base (Map 3-8) in areas identified as having above-average tortoise sign; the JohnsonValley plot is east of this area. It is noteworthy that the Kramer Hills, Lucerne Valley, andStoddard Valley study plots showed the smallest population declines during the 10 to 15 yearsthey were surveyed (1996 Berry Memorandum), and are included in three regions that currentlysupport higher sign count areas.3.3.2.4.3 Desert Tortoise DistributionRevised Tortoise Range Map: Survey data were used to produce an updated tortoiserange map of current tortoise distribution (See Map 3-10). The 1984 range map (Map 3-7)identified approximately 11,255 mi 2 (7,203,107 acres) of tortoise habitat, whereas 11,134 mi 2(7,125,842 acres) are identified in the 2002 Tortoise Range Map 9 , which represents a reductionof about 121 mi 2 .Map 3-10 depicts three regions within the 2002 tortoise range: reduction areas, expansionareas, and areas requiring more surveys. These areas are discussed in detail in Appendix L.9 Each of these figures over-estimates occupied tortoise habitat, as dry lake playas, elevations above about 4,500feet, and other marginal or unsuitable habitats are included within both range lines. Nor do they imply anythingabout the relative of densities occurring in the older and more recent ranges.Chapter 3 3-91