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A multi-stressor risk assessment was conducted at Yuma Proving Ground, Arizona, as a demonstration of the Military Ecological Risk Assessment Framework. The focus of the assessment was a testing program at Cibola Range, which involved an Apache Longbow helicopter firing Hellfire missiles at moving targets, that is, M60-A1 tanks. This article focuses on the wildlife risk assessment for the helicopter overflight. The primary stressors were sound and the view of the aircraft. Exposure to desert mule deer (Odocoileus hemionus crooki) was quantified using Air Force sound contour programs NOISEMAP and MR_NMAP, which gave very different results. Slant distance from helicopters to deer was also used as a measure of exposure that integrated risk from sound and view of the aircraft. Exposure-response models for the characterization of effects consisted of behavioral thresholds in sound exposure level or maximum sound level units or slant distance. Available sound thresholds were limited for desert mule deer, but a distribution of slant-distance thresholds was available for ungulates. The risk characterization used a weight-of-evidence approach and concluded that risk to mule deer behavior from the Apache overflight is uncertain, but that no risk to mule deer abundance and reproduction is expected. [ABSTRACT FROM AUTHOR]

A multiple stressor risk assessment was conducted at Yuma Proving Ground, Arizona, as a demonstration of the Military Ecological Risk Assessment Framework (MERAF). The focus was a testing program at Cibola Range that involved an Apache Longbow helicopter firing Hellfire missiles at moving targets, that is, M60-A1 tanks. This article describes the ecological risk assessment, using the MERAF, for the tracked vehicle movement component of the testing program. The principal stressor associated with tracked vehicle movement was soil disturbance, and a resulting, secondary stressor was hydrological change. Water loss to desert wash vegetation was hypothesized to result from increased infiltration and/or evaporation associated with vehicle disturbances to surrounding desert pavement, potentially affecting mule deer as well as vegetation. The simulated exposure of wash vegetation to water loss was quantified using estimates of disturbed land area from a digital orthogonal quarter quadrangle aerial photo and field observations, a 30-m digital elevation model, the flow accumulation feature of ESRI ArcInfo GIS, and a two-step runoff process dependent on soil characteristics and the extent of disturbance. In all simulated scenarios, the absolute amount of water lost increased with distance from the disturbance downslope in the washes; however, the percentage of water lost was greatest in land areas immediately downslope of a disturbance. Potential effects on growth and survival of desert wash trees were quantified by comparing water availability from the hydrologic model to water volume thresholds required for wash trees to survive and persist, derived from a local study. For both the incremental risk of the test program and for the combination of test and pretest disturbances, this demonstration of MERAF found no significant risk to either wash vegetation growth and survival or mule deer abundance and reproduction. [ABSTRACT FROM AUTHOR]

A multiple stressor risk assessment was conducted at Yuma Proving Ground, Arizona, as a demonstration of the Military Ecological Risk Assessment Framework. The focus was a testing program at Cibola Range, which involved an Apache Longbow helicopter firing Hellfire missiles at moving targets, that is, M60-A1 tanks. This article describes the ecological risk assessment for the missile launch and detonation. The primary stressor associated with this activity was sound. Other minor stressors included the detonation impact, shrapnel, and fire. Exposure to desert mule deer (Odocoileus hemionus crooki) was quantified using the Army sound contour program BNOISE2, as well as distances from the explosion to deer. Few effects data were available from related studies. Exposure-response models for the characterization of effects consisted of human “disturbance” and hearing damage thresholds in units of C-weighted decibels (sound exposure level) and a distance-based No-Observed-Adverse-Effects Level for moose and cannonfire. The risk characterization used a weight-of-evidence approach and concluded that risk to mule deer behavior from the missile firing was likely for a negligible number of deer, but that no risk to mule deer abundance and reproduction is expected. [ABSTRACT FROM AUTHOR]