CWD first showed up in the late
1960s in northern Colorado and is
believed to be spread from game
farms and high-fence shooting
operations to wild populations of
deer and elk. It is now arguably
the greatest modern threat to
America’s deer and elk herds.
If you study that CWD distri-
bution map, you’ll notice two
big concentrations of the dis-
ease west of the Mississippi,
in southern Canada’s Grain
Belt, and in Wyoming. What’s
between those two? Montana,
where I live.
Montana has been official-
ly CWD-free since 1998, when
it was detected in captive elk
on a game farm in the western
part of the state. That game
farm was “depopulated,” as the
eradication of animals is eu-
phemistically called, a ballot
initiative was passed banning
future game farms, and the
state’s deer and elk hunters
breathed easier, figuring we
had dodged the CWD bullet
that, at the same time, was
decimating Wisconsin’s wild
whitetail herd.
But we Montanans have
been watching CWD creep
closer from the south and the
north. Montana’s Fish, Wildlife
& Parks Department (FWP)
has, too, and after years of am-
bivalence about CWD, FWP
last year launched an intensive
monitoring campaign on its
border with Wyoming. Both
shockingly and somewhat un-
surprisingly, the disease was
detected in two mule deer
south of Billings.
The detection triggered a re-
sponse that had been planned
for years. There are two models
for CWD response and man-
agement. One is Wisconsin’s,
courtesy
Montana’s Containment
Efforts
which was to draw a radius
around detection areas and
eradicate every deer within it,
with or without landowners’
permission. Then there’s Wyo-
ming’s model, which is to sam-
ple for CWD but then to basi-
cally track its spread, with little
depopulation of affected herds.
Montana has tried to strike a
middle ground.
The first step is to establish
prevalence, or how extensively
the disease has spread through
the deer population. In order to
do that, the state established a
special late season and issued
tags to hunters to kill a number
of deer—around 325—in the
CWD-positive area. Samples
from all those deer, plus even
more killed during the 2017
general season, were tested,
and 10 came back as positive.
“That works out to 2 per-
cent overall prevalence in the
deer herds tested,” says Emi-
ly Almberg, a Montana Fish,
Wildlife & Parks researcher.
“Broken down by species, the
prevalence in mule deer was 2
percent while the prevalence
in white-tailed deer was 1 per-
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