Yellowstone's Northern Range - Greater Yellowstone Science ...

THE NORTHERN RANGE
Figure 7.7.
Environmental
factors that favored
increases in elk
numbers ill the 1970s
and 1980s also
favored increases in
mule deel: NPS
photo.
growth forests (1995). Recent estimates were of
about 200 on the northern range but counts are
often inconclusive because moose are solitary
animals that spend much time in forested areas. In
winter, northern range elk ate about 80 percent
grasses, 17 percent browse, and 3 percent forbs
(Houston 1982). By contrast, moose are primarily
browsers. From 1986 to 1990, Tyers (U.S. Forest
Service, Gardiner Dist., unpubl. data) studied
moose on Yellowstone's northern range in a slightly
expanded area that included adjacent, higher
elevation areas not studied by Houston. Tyers
found that moose ate 39.6 percent subalpine fir,
25.5 percent willows, 10.6 percent lodgepole pine,
4.6 percent gooseberry, and 4 percent buffaloberry.
Most of their browsing occurred in 300+ year-old
lodgepole forests, the oldest sproce-fir forests, and
the 100- to 300-year-old lodgepole forests. Moose
are able to winter in snow 150 percent as deep as
can elk, and tend to winter at higher elevations than
elk.
Moose population data on the northel11 range
is meager compared to the other ungulate species,
which is a function of their solitary habits in
forested habitats. The Northern Yellowstone
Cooperative Wildlife Working Group stopped
conducting aerial censuses for moose after 1992,
believing them to be inaccurate but lacking a better
method. Still, there is evidence of a decline of
moose on the northern range since the 1960s, and
particularly since the fires of 1988. While competitive
exclusion by elk cannot be ruled out as a
reason for the suggested decline, the fires and
overhunting may be factors as well.
86
MULE DEER
Mule deer winter in the Gardiner Basin from
the vicinity of Mammoth Hot Springs, Wyoming,
to the south end of Yankee Jim Canyon (Figure
7.7). The herd's winter distribution is contiguous
with that of other mule deer herds north of Yankee
Jim Canyon. The bulk of the herd winters beyond
the northern border of Yellowstone National Park
because of shallower snow depths at those lower
elevations (Figure 7.8).
Northern range mule deer numbers, like
those of many greater Yellowstone ungulate herds,
increased during the 1980s when the northern
Yellowstone elk also were increasing (Appendix
B). Even if several research projects had found
evidence of elk olitcompeting mule deer for food or
other resources, the doubling of the mule deer herd
is circumstantial evidence that competition is not
causing the mule deer herds significant problems.
In the winter of 1993, P. Gogan (U.S. Geol.
Surv., pers. commun.) began a research project
designed to identify the summer range of the
northern Yellowstone mule deer herd, and determine
the extent to which it had been affected by the
1988 fires. Sixty adult female mule deer were
captured in the Gardiner Basin and fitted with radio
collars in March 1993. These does were relocated
by aircraft to determine their seasonal movement
patterns and location of summer ranges. An
additional 25 adult females were captured and
radiocollared in the same area in March 1995.
Results of radio tracking showed that some 30
percent of the deer were year-round residents of the
Gardiner Basin, simply moving to higher elevations
in the same drainage in
which they winter. The
remaining 70 percent of the
deer moved seasonally. Those
deer wintering on the east side
of the Yellowstone River
generally moved to the east, to
summer ranges in all the
drainages between Crevice
Creek and Cooke City, as well
as the Mirror Plateau and to the
northeast to Mill Creek in