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Moose
Survival
In addition to hunting, the three major
determinants of moose survival are predators, snow conditions and disease.
The timber wolf is the most serious predator of
moose in the NWT. They often detect moose by scent. When the moose population is
thriving, wolves act as a culling agent for old or diseased animals and weakened
calves. When the moose becomes aware of danger, it can either stand and fight or
run. A single wolf or a small group of wolves are no match for a healthy moose,
which uses all four powerful legs to strike an opponent. However, a group of
more than four or five wolves can pull down and kill a large moose. If the moose
decides to run, wolves give chase and attempt to slow the moose by grabbing it
by the nose, rump, or hocks. In this case, an organized attack by a large group
of hungry wolves is often fatal for the moose.
In the Yukon and Alaska, calf predation by grizzly and black bears has been
shown to have a major effect on the size of moose populations. This may also be
the case in the NWT, but to date no data are available.
 Predation and snow conditions are interrelated factors that can have a
significant effect on moose numbers. When snow is deep and moose ''yard''
together, they are more accessible in greater numbers to wolves. Moose have
relatively long legs that allow them travel through deep snow easier than most other
ungulates. However, snow
depth of over 90 cm greatly hinders their movements and their
foraging ability is seriously restricted. Crusted snow can also be detrimental
to moose in that it can pierce the skin on the forelegs and crack the hooves,
making it vulnerable to predation.
Moose are susceptible to a variety of parasites.
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Tapeworms that cause cysts do not directly
influence moose mortality, but instead hinder their response to stress. Three
types of tapeworms that can be found in moose in the NWT are
liver
tapeworm cysts (Taenia
hydatigena),
hydatid
disease in the lungs (Echinococcus
granulosus),
and
muscle
tapeworm cysts (Taenia
krabbei).
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"Moose disease" is caused by a parasitic roundworm (P. tenuis)
carried and transmitted by white-tailed deer. Infestation in moose
can damage the central nervous system and ultimately invade the
brain, usually causing death. The symptoms of the disease include
walking in circles, bumping into objects, losing fear of man, and
general lack of co-ordination. "Moose disease" is not found in the
NWT and Western Canada at this time, which can probably be
attributed to the low populations of white-tailed deer in these
areas.
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Ticks
(Demacentor albipictus) feed on the blood of the moose, severely
weakening the animals and causing hair loss which then increases
heat loss. External ticks have been reported on moose in the South
Slave and Deh Cho regions.
In some places a significant number of moose are killed through collisions with
motor vehicles. So far, this is not a problem in the NWT because there are so few roads. Other minor causes of mortality to moose are
drowning, falls, and wounds caused during rutting combat.
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