Ecological Studies of the Timber Wolf in Northeastern Minnesota — John Shaqi
Ecological Studies of the Timber Wolf in Northeastern MinnesotaMech, L. David
Science
Ecological Studies of the Timber Wolf in Northeastern Minnesota
Mech, L. David
Deer -- Minnesota; Gray wolf -- Behavior -- Minnesota; Gray wolf -- Ecology -- Minnesota
Once the average rate of kill is known, the average food consumption
per wolf can be calculated. The average deer (considering both fawns
and adults) from the Superior National Forest during winter weighs
about 113 pounds (calculated from Erickson _et al._ 1961), and an
arbitrary 13 pounds can be deducted from this for inedible portions.
This leaves 100 pounds of deer per wolf per 18 days, or 5.6 pounds per
wolf per day. This figure is much less than the 10 to 14 pounds
estimated consumption rate for wolves feeding on moose on Isle Royale
(Mech 1966a). However, much variation can be expected in an animal
whose physiology must be adapted to a feast-or-famine existence.
Wolves can be maintained in captivity on 2.5 pounds of meat per day,
and large active dogs (_Canis familiaris_) require 3.7 pounds per day,
so it is likely that the minimum daily requirement for wolves in the
wild is about 4.0 pounds per day (Mech 1970). This figure agrees well
with the estimated consumption rate for our study area.
FOOTNOTES:
[19] _Kolenosky, G. B. Wolf movements, activities and predation impact
on a wintering deer population in East-Central Ontario. (Manuscript in
preparation for publication.)_
Relative Population Density
Censusing wolves in a 1.5-million-acre study area is a difficult task,
and we have no direct information on which to base a population
estimate. However, some deductions can be made about the relative
population densities in our study area between the period 1948 to 1953
and the period of the present study, 1967 to 1969.
R. A. Rausch (1967a) hypothesized that the frequency of large packs is
higher when population density is high, and presented evidence
supporting this idea. On this assumption, a comparison of pack-size
distributions between various periods can indicate relative population
densities between periods. The advantage of this method is that it
eliminates the usual type of year-to-year biases in wolf censuses such
as might result from differences in precise census route, type of
aircraft, skill of observers, and other conditions. Only a difference
that would cause a bias in the _size_ of the packs seen would be of
importance.
Therefore, we tested the difference in size distributions of population
units between the 1948-53 study period and the present period (table
1), using a Kolmogorov-Smirnov two-sample test (Siegel 1956). The
average "pack" size in the earlier years was 2.8, compared with 4.2 at
present; thus pack sizes are significantly larger at present (95
percent level). This indicates that the population density from 1967 to
1969 may have been higher than from 1948 to 1953. This apparent change
may be attributable to a reduction in snaring, trapping, and aerial
hunting that took place between the two periods as a result of changes
in State game regulations.
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