State’s CWD efforts gain the spotlight
By Tim Eisele Correspondent
Madison – Wisconsin’s battle with chronic wasting disease was
front and center at the second International CWD Symposium that was
held in Madison, July 12-14.
Reports on Wisconsin’s experience, the first time that CWD had
been found in a wild deer herd east of the Mississippi River, were
provided throughout the symposium.
The Wisconsin DNR launched an all-out attack, one of the first
in the country, to try to eradicate the disease. Alan Crossley, DNR
CWD project leader, said Wisconsin has learned a lot about CWD
since it was discovered here, but not how the disease is
“We have a sense of distribution based on our sampling of deer,
but we can’t stick our head in the sand knowing that we have CWD,”
he said. “We are on the right path despite some people wishing it
(CWD) would go away. There is no doubt in my mind that CWD will not
go away. We are the professionals responsible for managing the
(state’s) resources, and now is the time to give it our best shot
to eradicate CWD.”
Crossley stressed the importance for landowners, hunters,
legislators, and administrators to be patient and give the DNR the
time and tools needed to be successful.
CWD was known to be present in the wild primarily in the western
U.S. prior to its discovery in Wisconsin in 2002, though this
spring CWD was found in a captive deer herd in New York, and
further sampling has found it in some wild deer in the same
As of 2005, the primary locations of CWD-positive deer in
Wisconsin’s wild herd have been in the area between Iowa and Dane
counties, and in the southeast in Rock and Walworth counties.
“In the Western Disease Eradication Zone (Iowa and Dane) there
are some sections of land that have had as many as 16 deer test
positive,” Crossley said.
CWD appears to be clustered there, although positives have been
found away from the main area. During testing of dead deer in 2004,
145 deer out of 19,167 tested positive. Of those, 143 were located
within the disease eradication zones and two were within a larger
area, the Herd Reduction Zone.
Crossley said some people may wonder why the state should worry
about CWD when only 1 percent of the herd in the area has it. He
points out that 10 to 12 percent of the deer in one section of land
“Eighty percent of all the positive deer found so far in the
Western Disease Eradication Zone (456 deer) are found in a
126-square-mile area,” he said. “So far, out of more than 7,500
fawns tested for CWD, only nine have tested positive. It appears
that the prevalence of the disease increases with age and the rate
of increase is faster in males than in females.”
In the core area’s adult deer, the prevalence of CWD increases
as deer get older, but the prevalence is always higher in males
than in females, research shows. For instance, in 4-year-old or
older deer, less than 5 percent of the does have CWD, but almost 13
percent of the bucks have CWD.
Crossley said the same trend has been found in mule deer in
Colorado. He said he doesn’t know how significant it is to the
spread of the disease. The prevalence in the core area is going
down slightly in does, but staying about the same in bucks.
Crossley compares the state’s CWD fight to Michigan’s fight
against bovine tuberculosis. After TB was discovered in Michigan,
the prevalence in the core area moved up and down, but after three
years began declining. After eight years it was less than half what
it once was.
“What we need is patience and time, to assess whether we are
making progress,” Crossley said.
In the Western Disease Eradication Zone, helicopter surveys have
estimated there are about 28 deer per square mile of range, or
about 17 deer per square mile of land. In the 210-square-mile core
area, the population has come down from 35 deer per square mile of
habitat in 2003, to 28 deer in 2004 and 23 deer in 2005.
In Unit 70A, (which is fully within the Western Disease
Eradication Zone) helicopter surveys show the population has come
down from 34 deer per square mile of habitat in 2004 to 30 deer
this winter, or a 13-percent reduction.
Julie Langenberg, DNR veterinarian, told participants that
Wisconsin’s management goals focus on limiting the spread of CWD
from the known infected areas, and trying to eradicate the disease
“We’re basically treating CWD as a foreign animal disease,”
Langenberg said. “We feel it is possible since this is a relatively
recent introduction into the state and that it’s not a long-term
part of the ecosystem. The key effort is (to greatly reduce) the
deer population in the infected areas.”
She cites writings by Aldo Leopold in 1933 that the temporary
removal of a whole population can be done to prevent the spread of
infections within a population of animals.
A question facing the DNR is how drastically it needs to reduce
deer populations. It may be possible, Langenberg said, to eradicate
the disease without killing all of the deer, but this is an ongoing
The main focus of CWD control is through hunter effort, using
programs such as September-to-March hunting, earn-a-buck
requirements, and unlimited tags.
“To be blunt, we’re using sticks,” Langenberg said. “The use of
earn-a-buck shows that it has an effect on increasing the overall
harvest. But as bucks age, the prevalence of CWD increases, and
we’re also concerned about buck harvest and are considering
modifications of the EAB stick.
“We also use carrots, and have used monetary incentives to
reward hunters for deer they harvest. Additional carrots include
the venison pantry donation program and free permits to
Langenberg acknowledges that there are landowners who resist the
DNR program, and the DNR has analyzed data to examine locations of
landowners who sign petitions against harvesting deer and whether
it has been correlated to deer harvested in specific sections. DNR
officials say they see no correlation.
The DNR does use sharpshooters to kill deer in the core area,
and so far has removed 15 percent of the CWD-positive deer.
“The control of deer feeding and baiting is also important, and
it is based on animal science and studies in Michigan with TB and
deer,” Langenberg said. “We have a strong sense that a total ban on
baiting and feeding should occur in our state. In 2002 we had an
emergency statewide ban on baiting and feeding, but as a result of
an only 50-50 split in public opinion afterward, it is now only
banned in counties where CWD has been found.”
Langenberg said the DNR wants to kill more older bucks as a way
of reducing the prevalence of CWD.
She said the Department of Agriculture Trade and Consumer
Protection has depopulated five of seven deer farms where CWD had
been found. There are still legal challenges to other depopulation
orders and the state needs help finding ways to help those owners
who would like to get out of the business.
CWD challenges for DNR
Crossley highlighted three issues challenging the DNR:
1) The cost of disposing of carcasses. All of the heads from
deer shot in the DEZs and carcasses from roadkills add up to a
significant cost of disposal. In 2002, the cost was $1 million; it
has been brought down to $500,000 in 2004.
“What we need is some form of indemnification, allowing disposal
in landfills, which would provide a cost saving,” Crossley
2) How hard will deer hunters be willing to work? As the DNR is
more successful in reducing the population, hunters will see fewer
deer and may become less supportive of reducing the number of
3) The existence of refuges, and how to shoot deer in those
refuges. DNR helicopter surveys show some areas only one to nine
deer, but in one square mile the helicopter counted 105 deer.
“I keep favoring education and working with everybody out there,
but we already hear from some people who are not willing to go
further, and it is a very sticky wicket for the DNR to deal with,”
He said statewide surveys show that 70 to 80 percent of
respondents feel the DNR should continue with its efforts. However,
that does not mean 70 to 80 percent think the DNR is doing the
There is no scientific evidence that CWD will burn itself out if
it is left alone. Surveys show that nearly half of the hunters
would stop hunting if CWD reaches 50 percent of the herd.
“Our goal is to have a healthy herd,” Crossley said. “The keys
to success are most important, hunters and landowners, along with
the captive cervid industry, cooperation among sister agencies,
adequate human and financial resources, a long-term commitment to
the program, and an aggressive effort to contain the spread and
reduce prevalence of the disease.”