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Mueller, F.P. 1995.
Tundra esker systems and denning by grizzly bears, wolves, foxes, and
ground squirrels in the Central Arctic, Northwest Territories. 68
pp.
ABSTRACT
I
investigated den characteristics for grizzly bears (Ursus arctos), wolves (Canis lupus), red foxes (Vulpes
vulpes), arctic foxes (Alopex
lagopus), and arctic ground squirrels (Spermophilus
parryii) during July and August 1994 in the Lac de Gras region of
the Central Arctic, Northwest Territories.
All five species established dens almost exclusively on sandy
eskers rather than on rocky uplands or on sedge meadows.
The estimated proportions of the main habitat types in the study
region are upland (54.7%), meadow (10.5%), and esker (1.5%). During
helicopter searches the dens of bears (n = 32), wolves (n = 37), foxes
(n = 39), and ground squirrels (n = 2448) were found on eskers
significantly more often than expected by chance (p < 0.025).
The site characteristics measured at four types of den sites (bear, n =
23; wolf, n = 22; fox, n = 19; and squirrel, n = 18) and two types of
control sites, adjacent and random (n = 36) varied significantly.
The size of esker materials at den sites was significantly
smaller than the size of esker materials at both adjacent control and at
random control sites. Esker
materials required by industry are on average significantly larger than
those used by all four types of denning animals.
The slope at bear dens was significantly steeper than the slope
at all other types of sites. Dens
of both bears and squirrels tended to be on southern slopes. Significant differences were also found in the percentage
cover of vegetation between the four types of den sites and the two
types of controls. Percentage
shrub cover was relatively high at bear dens.
Percentage cover of grass, sedge, and fireweed (Epilobium spp.) was relatively high at wolf dens.
Den sites of wolves, foxes, and ground squirrels were relatively
large complexes, usually with numerous burrows.
Bear dens had only a single burrow.
The biomass of vegetation at den sites of wolves, foxes, and
ground squirrels was relatively high and likely resulted from the
activities of animals in repeated years. In contrast, vegetation at bear
dens undergoes no alteration which suggests a short period of use.
There were no significant differences in total nitrogen or in
water content among sites. Total carbon content was significantly lower
at random control sites compared to den sites.
The above results suggest that it may be feasible to evaluate the
suitability of habitat for denning of bears, wolves, foxes, and
squirrels prior to industrial activities. Preliminary recommendations for further studies and impact
mitigation are provided. |
