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1 December 2005 Head to Head
Jack C. Turner, Charles L. Douglas, Cecil R. Hallum, Paul R. Krausman, Rob Roy Ramey
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In the absence of a reproducible validated critical-habitat delineation for Nelson's bighorn sheep (Ovis canadensis nelsoni) in the northern Santa Rosa Mountains, California, Turner et al. (2004) developed a quantitative habitat model based on biotic and abiotic habitat parameters comprised of the primary constituent elements allegedly used in the United States Fish and Wildlife Service's (USFWS) habitat model (USFWS 2000, 2001). Bighorn distribution and location (observation) data used by the USFWS in its model were 96% explained on the basis of the Turner et al. (2004) model; no validation or prediction could be made from the USFWS model (USFWS 2000, 2001). Criticisms by Ostermann et al. (2005) of the Turner et al. (2004) model emphasize a basic miscomprehension by Ostermann et al. (2005) of the differences between habitat characterization and habitat utilization. Most of the Ostermann et al. (2005) critique relates to data that were not provided to Turner et al. (2004). Failure of Ostermann et al. (2005) to fully grasp the sampling strategy used by Turner et al. (2004) relates to an incomplete comprehension of the statistical methodology employed rather than with the statistical procedures themselves. Claims by Ostermann et al. (2005) that Turner et al. (2004) made extrapolations to misdirect bighorn recovery efforts, drew inferences to other bighorn populations, alleged the northern population was normal, and equated sheep density (frequency of observation) to habitat quality are without substantiation, example, or merit. Contentions of problematic water source data are unsupported by the literature cited by Ostermann et al. (2005). The permissive attitude of resource agencies allowing management and conservation efforts to be directed by special interests largely in the absence of independent scientific scrutiny, casts a question of legitimacy over this Endangered Species Act listing, recovery strategy, and critical habitat delineation.

Jack C. Turner, Charles L. Douglas, Cecil R. Hallum, Paul R. Krausman, and Rob Roy Ramey "Head to Head," Wildlife Society Bulletin 33(4), 1465-1473, (1 December 2005).[1465:OAOAFH]2.0.CO;2
Published: 1 December 2005

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habitat modeling
logistical regression
Native mountain sheep
Nelson's bighorn sheep
Ovis canadensis nelsoni
Peninsular Ranges
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