Dames & Moore, 1999 - USDA Forest Service

Tailings Piles
A flock of violet-green swallows (>50 birds) and a few barn swallows foraged daily for insects over the
tailings piles. Swallows were not observed in other habitats, surrounding the Site, with the exception of the
open areas around Holden Village. A large flock of American pipits (ca. 35 birds) was also observed
foraging at the tailings piles; this species nests in open alpine areas and probably uses the tailings pile
primarily during migration. Two immature red-tailed hawks were observed hunting along the tailings piles
suggesting a nest in the area.
A variety of avian species are expected to use both the tailings piles and the affected areas of Railroad
Creek, to varying degrees. All insectivorous species which use the riparian zone surrounding Railroad
Creek probably consume flying insects which spend their larval stage in the creek. Vegetation gleaning
species (warblers, vireos, chickadees) would consume fewer such insects than species which hawk for
insects on a regular basis (flycatchers, cedar waxwings). Dippers consume almost exclusively aquatic
insects.
Most bird species living in the vicinity of the Site are unlikely to use the tailings piles on a regular basis.
Birds of the Cascades are adapted to structurally complex habitats and the tailings piles are predominately
structurally simple. Some species, however, are likely to frequent the tailings piles, including raptors and
owls in search of small mammals. Although small mammal densities on the tailings are probably not high,
suitable habitat for a variety of species does exist and the lack of cover makes them available to avian
predators.
Other avian species observed on the tailings or likely to be present include barn and violet-green swallows,
American pipits, and common nighthawks. Swallows feed on airborne insects which may originate from
the tailings pile and railroad creek. During aquatic insect hatches, a large proportion of swallow diets
consist of insects from Railroad Creek. Pipits eat insects and seeds gleaned from the ground and are
therefore likely consuming forage originating from the tailings pile. However, pipits are only visitors to the
area during migration. Common nighthawks, which also feed on airborne insects, are ground nesters, and
prefer open, gravelly nest sites.
4.6.2.5 Mammals
Bat species which are potentially present in the Site area are listed in Table 4.6-9. The western big-eared bat
appears to roost exclusively in caves and mines, buildings, and bridges, while most of the other species will
also roost under loose bark and in rock crevices. For most species, caves, mines, and buildings are used for
maternity roosts and hibernacula (Christy and West, 1993).
Potential bat roosts exist at the 1500-level main portal, the 1500-level ventilator portal, and in the 1 loo-,
500-, and 300-level portals. Depending on the time of year, the mine portals may be used for night or day
roosts, colonial roosts (males and non-breeding females), maternity colonies, or hibernacula. The 1500-
level main portal which provides both roosting habitat and drinking water, appears to be the most suitable
. for bat roosting.
During the bat surveys, bats were observed at dusk near the surface of the 1500-level main mine portal
drainage. However, there was insufficient daylight to determine whether they were exiting or enteringthe
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17693-005-019Uuly 19, 1999;4:51 PM:DRAFT FINAL RI REPORT