Dames & Moore, 1999 - USDA Forest Service

of between a low of 34 ha. for does, and an hi@ of 819 ha. for bucks. Summer home ranges of does
averaged 92 ha., while adult males ranged over areas of between 52 and 66 ha.
The food ingestion rate for herbivorous mammals was estimated as:
F (kgld) = 0.0875 x (kg Body ~ei~ht)~.'~'
The largest mature male mule deer weigh about 150 kg but the average weight in west coast adult
populations is about 60 kg. Mule deer consume about 22 g dry foodkg body weightlday (Alldredge et al..
1974). Mule deer obtain a large portion of their water requirements from vegetation, but consume between
47 and 70 mUkg body weightlday when confined in pens in the summer. In addition, mule deer are
assumed to ingest soil equivalent to about 2 percent of their diet (Sample et al., 1997).
No direct measurements of concentrations of metals & plants were obtained at the Holden Mine site.
However, Efioympson et al. (1997) have summarized the available data on soil-to-plant uptake factors
(Table 7.2.3-lo), and these can be used to estimate concentrations of metals in the plants (Table 7.2.3-6) at
the Holden Mine site.
Not all of the metal concentrations found in the diet or in incidentally ingested soil are bioavailable. Table
7.2.3-1 1 shows the bioavailability of metals fiom soils and the default bioavailability assumptions for plant
matter.
Table 7.2.3-12 uses these soil-plant uptake algorithms, UCL concentrations of metals, and bioavailability
from soil and tailings piles at the Holden Mine site to predict potential doses that mule deer may receive.
Deer Mouse
Deer mice are highly opportunistic omnivorous rodents (EPA, 1993) which largely consume seeds during
the fall and winter, and arthropods during the summer. They cache food for the winter in the northern extent
of their geographical range. They have home ranges from 0.014 to 0.128 ha, depending on population
density. Sample et al. (1996) provided an algorithm for the food consumption by rodents:
7-2 1
F(kg/d) = 0.0306 x (kg Body 7-22
Deer mice weigh about 0.022 kg and ingest about 0.16 kg foodlkg body weight per day. Non-seed food
provides a large portion of the animals water requirement. Incidental soil consumption is less than 2
percent of the diet volume. Although deer mice may ingest arthropods at the site, there are no models by
which to estimate the metal concentrations in arthropods. Therefore, it was assumed that their diet was
100 percent plant matter. However, since seeds contain much lower metal concentrations than foliage
(Beyer et al., 1985), this was considered a conservative estimate of the dose to a small herbivore. In
addition, it was assumed that deer mice obtained all of their water fiom the highest concentrations in
Railroad Creek. The plant uptake models of Efroymson et al. (1997) and bioavailability factors (Table
7.2.3-1 1) were used to estimate the dose (Table 7.2.3-1 3).
Deer mice may also serve as food for animals such as mink and hawks. Sample et al. (1998) provide
algorithms (Table 7.2.3-10) by which the metal concentration in small mammals may be estimated (Table
7.2.3-6). These concentrations were used in estimating the doses to carnivores, below.
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