NEPA--Environmental Assessment

ptarmigan is expected under Alternative 3 than under Alternative 2, improvements due to adopting
the adaptive management approach are likely to be too small to affect ptarmigan populations or the
total amount of habitat available in the Silverton Landscape.
Selecting Alternative 3 would be beneficial for wolverine, although less beneficial than selecting
Alternative 1, but more beneficial than selecting Alternative 2. About 22% of alpine areas would be
suitable for sheep grazing under Alternative 3, which is a slight reduction from the 29% of alpine
areas suitable for sheep grazing under Alternative 2. Alpine areas provide the core of potential
wolverine habitat in the landscape, and include wolverine denning habitat. Although there appears
to be little difference between Alternative 2 and Alternative 3 in the amount of alpine area affected
by sheep grazing (about 7% reduction), the landscape is in the center of a region identified by the
CDOW and wolverine researchers as providing some of the best and most extensive potential
wolverine habitat in the state of Colorado. For this reason, even small changes in risk factors may
provide substantial benefits to a species that is documented to be highly sensitive to human
disturbance. However, it must be remembered that wolverine has not been confirmed to occur in the
landscape or anywhere in southwest Colorado in many decades. Given the lack of confirmed
wolverine occurrence in southwest Colorado, the risk of disturbance to individual animals from
sheep grazing activities is probably low.
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