West Mojave Plan FEIR/S - Desert Managers Group

Noise: Krzysik (1994) stated: “…noise and vibrations associated with live-fire exercises[at Fort Irwin] are detrimental to wildlife populations,” but did not provide any data to supportthe conclusion. The Recovery Plan (USFWS 1994) listed the following potential impacts, againwithout any data to support the conclusions. Noise impacts may cause disruption ofcommunication and damage to the auditory system, which may affect an individual’s ability toeffectively communicate and respond in appropriate ways. In several places, the Recovery Planreferred to “noise pollution” or listed noise as one of the potential impacts, but provided nospecific data.In his threats analysis, Dr. Boarman (2002) reiterated the information given in theRecovery Plan, which is recited above, plus the following observations. A study conducted byBowles et al. (1999) showed very little behavioral or physiological effect on tortoises of loudnoises that simulated jet over flights and sonic booms. They also demonstrated that tortoisehearing is fairly sensitive (mean = 34 dB SPL) and was most sensitive to sounds between 125and 750 Hz, well within the range of the fundamental frequency of most of their vocalizations.The authors concluded that tortoises probably could tolerate occasional exposure to sonic boomlevel sounds (140 dB SPL), but some may suffer permanent hearing loss from repeated longtermexposure to loud sounds such as from OHV and construction blasts. Boarman (2002) alsoindicated noise or vibration might affect tortoises that live alongside railroads, but found therewere no studies to document the impact. He concluded, it is not known if train noise negativelyaffects the behavior, audition, or reproductive success of these tortoises.Habitat Recovery Rates: Lovich (1992) reported that recovery to pre-disturbance plantcover and biomass may take from 50-300 years while complete ecosystem recovery may requireover 3,000 years. Webb et al. (1983), citing Lathrop and Archbold (1980), predicted a recoverytime of a century for pipeline berms and trenches, pipeline road edges, and powerline pylons androad edges. They state that an estimate of recovery based on vegetative composition could be “atleast three times greater” than the estimate for biomass, again assuming that recovery follows alinear trend. These researchers were referring to natural rehabilitation of unused sites. There islittle or no opportunity for perennial plants to become re-established on road shoulders, erosionditches, etc. that are regularly maintained.3.3.2.5.2 Natural Mortality FactorsThis section addresses “natural” mortality factors, including predators, drought anddisease. The term “natural” does not, however, mean that these occur independently of man.Although some mortality factors may naturally occur, they are often exacerbated by humanactivities that have affected the natural balance that likely existed prior to man’s use of thedesert. Disease is discussed in this section, although its origin in wild tortoises (i.e. a naturaloccurrence) or pet populations (i.e. introduced by man) remains unknown. Natural predators ofpost-hatching tortoises include golden eagle, common raven, badger, coyote, kit fox (Berry 1990,Boarman 2002).Chapter 3 3-102