Figure 5. Dorsal (top photo) and ventral (bottom photo) views of the four
basic pelt patterns for
                      immature muskrats taken in fall and winter.
white stripe is common. This pattern    However, as long as it is important
in
is rarely found in the older immatures,  some years, we have separated it
from
but in the 1958 trapping season it      the I pattern by the numeral "O"
(Fig.
showed up with surprising frequency.    6). In terms of amount of pigmentation
Habitat conditions during the summer     there is very little difference
between
of 1958 were unusually poor for musk-   the I and 0 patterns.
rats, with extreme drought conditions      The relatively large number of
pelts
prevailing. Whether this dark-phase     from kits of the same litter but
taken
pelt is directly associated with detri-  individually over a period of time,
mental habitat changes is not known.     were also checked. If we assume
that

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