Wildlife Specialist report

microhabitat in the desert landscape for many small mammals (Bissonette and Rosa
2009). Underhill and Angold (2000) described an effect zone of up to 100 meters as
causing visible impacts on roadside ecological communities.
While studies show that small mammal density is greatest along large, mostly paved,
roadways (Adams and Geis 1983, Adams 1984, McGregor et al. 2008, and Bissonette
and Rosa 2009), few researchers have done comparative studies along rural dirt roads.
One study that did look at more rural county roads (Adams and Geis 1983) showed that
small mammal density increased away from the road right of way. In this analysis it is
assumed that most roads traversing the forest will be similar to the rural roads in Adams
and Geis (1983) study, rather than large interstate-type roads normally analyzed. Zone of
influence according to a review of literature appears to be between 100 and 400 meters.
The analysis uses a disturbance zone based on a median of 250 meters from roadways for
small mammals.
As with other groups of terrestrial wildlife, motorized/recreation effects to small
mammals can be grouped into two analysis factors:
1. A greater potential for harvest/direct effects, and/or
2. Disturbance/indirect effects.
Harvest or direct effect is be analyzed by miles of roadway within each habitat type and
disturbance or indirect effect is analyzed by distance from road out to 250 meters (acres).
Again, the effects were determined by using an approach that analyzes the change in
habitats that focal species are associated with among the different alternatives. These
selected species reflect general habitat conditions needed by other small mammals with
similar habitats.
Hooded skunk (Forest Service Sensitive Species Representative of Desert
Shrub/Grasslands, and Pinon-Juniper/Shrub Oak Woodlands Vegetation Cover
Types) – This species appears to be more common in desert and semi desert habitats, but
specimens have been taken in the Ponderosa pine forests. They can also be found in the
riparian communities consisting of sycamore, cottonwood and rabbitbrush. In Arizona
they prefer rocky slopes, base of cliffs and/or rocky sides of arroyos. They also prefer
intermediate elevations above the deserts but not the high mountains (BISON-M). This
species is fairly common on the Gila National Forest.
Botta’s pocket gopher (Forest Service Sensitive Species Representative of Desert
Shrub/Grasslands, and Pinon-Juniper/Shrub Oak Woodlands Vegetation Cover
Types) – Pocket gophers generally live where they can find good soils for excavation,
which could mean any environment from the desert up into the mountains. They may be
especially common in riparian areas, washes, farms and golf courses. They are active
year round. Signs of gophers include a mound of pushed up soil, which marks a
temporary den opening (desertusa). Tunnel systems stretching for over 150 yards are not
unusual. One study in Utah estimated that a single gopher moved as much as 1,130
kilograms of soil per year (a bit over 1 ton of soil). A typical tunnel will consist of a
subway system with numerous forks and side branches for food storage, fecal matter, and
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