Saturday, January 28th, 2023
Saturday, January 28th, 2023

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Deer estimates 2003: Lower than expected?

Editor

Madison Just after the Natural Resources Board (NRB) chairman
asked DNR wildlife officials for options on a longer gun deer
season under emergency rule for 2003, there came early rumblings
within the agency that the first cut at a 2003 deer population
estimate came in lower than expected.

On Jan. 22, the date of the last NRB meeting in Madison, board
chairman Trig Solberg said that, based on a lower-than-expected
deer harvest in 2002, a drop in gun and archery hunter numbers, and
a mild winter, it seemed reasonable to expect the 2003 deer
population estimate to run beyond the estimate of 1.6 million deer
heading into the 2002 deer seasons. With that in mind, Solberg said
it might be necessary to adopt a longer gun season for the 2003
season under emergency rule. He asked DNR wildlife officials to
bring any and all options for a longer season to the next NRB
meeting, which will be Feb. 26 in Madison.

At that time, Tom Hauge, DNR Bureau of Wildlife Management
director, said it might be a bit early to start thinking that way;
DNR biologists and wildlife managers had just started running 2002
deer harvest statistics through the state’s sex-age-kill (SAK)
formula.

About one week later, the DNR’s deer committee, which includes
two wildlife managers from each of the DNR’s five regions, plus
Central Office staff, took a look at the raw data. Numbers tossed
around within the committee that week weren’t supposed to leak out,
but word reached Solberg that the first cut came up with a
population estimate of 1.2 to 1.4 million deer for 2003, after
spring fawn production.

If those numbers are accurate, that would mean there would have
to be about 1.1 million deer, or perhaps less, on the ground right
now. That also would mean the 1.6 million estimate for 2002 was
high.

“If that ends up being the number, that’s crazy,” Solberg
said.

But, a number of DNR managers and biologists said deer hunters
who follow the annual SAK millings and antlerless quota-setting
process should temper any reactions to early numbers.

Robert Rolley of Madison is the DNR’s population ecologist.
Rolley grinds out that final number after receiving all kinds of
input from managers and biologists around the state. The final 2003
population estimate, antlerless quota, and list of Zone T units
will not be determined until Feb. 13 or Feb. 14. That list is due
for release on Feb. 14 or Feb. 15.

“So far, we haven’t talked about spring numbers,” said Rolley,
in an interview on Jan. 31. “We’re still working through numbers. I
haven’t estimated it (statewide deer numbers) yet, and until I do,
there is no number. I’m not sure who is coming up with 1.4
million,” he said.

DNR wildlife managers Tom Bahti of Green Bay and Mike
Zeckmeister of Antigo said hunters should know that the SAK formula
isn’t like a state or federal income tax form, where the bean
counters put numbers in the blanks, push a button and come up with
a number. While the SAK relies on the previous year’s buck kill to
help biologists reach a population estimate for the following year,
the rules aren’t hard and fast.

DNR deer researcher Tim Van Deelen and retired researcher Keith
McCaffery, both of Rhinelander, said there are at least 15 outside
factors that must be rolled into the creation of this year’s
population estimate, with some of the factors being the “prion
fear,” reduced hunter numbers, the latest possible gun opener, the
baiting ban, and weather during archery season and, to a lesser
extent, the gun season.

“When the gun deer season opener changes from Nov. 17 to Nov.
23, you can usually count on a 10 to 15 percent decrease in buck
kill; history shows us that,” Zeckmeister said.

Because the SAK relies heavily on the buck kill to reach its
conclusion for a population estimate, a decreased buck kill caused
for any reason, such as a late opener, would incorrectly tell
wildlifers that the overall population is lower than it really
is.

That’s where human evaluation comes into play in the SAK.

“The buck kill is very important for the SAK model, but let’s
just pretend we didn’t have SAK, or it was an inflexible model that
generates numbers based on input,” Zeckmeister said. “That’s not
what we have we make adjustments based on what happens out in the
field. If we have good hunting conditions frozen swamps and just
the right amount of snow  we can expect a good kill, even with a
lower population. We would look back at that year and say, Boy,
maybe we harvested more deer that we should have.’ So, we have to
adjust the SAK. That’s where professional input comes in.

“We’re looking back at not just 2002, but also 2001. I think
that’s wise management,” he said. “If we go through this whole
process that we’re going through now and the SAK shows we have
fewer deer, what’s wrong with that? Let’s go with it. But, we’re
not there yet.

“If you’re hearing 1.4 million, that’s premature and I’m not
sure who is generating it,” McCaffery said. “Every year, there is a
discussion on how to interpret harvest numbers and the population
estimate of the prior season. This year there may be more
discussion than normal because of unusual nature of the season,
license sales, the fair bit of CWD paranoia, which was especially
strong during the archery season, the restriction on baiting, you
name it. The managers and biologists are trying their best to sort
out various factors that may have influenced harvest.”

Rolley and Zeckmeister said the DNR’s best estimates will be
resolved in a meeting on Feb. 14.

Those estimates will be available to hunters who attend the more
than 40 deer unit review meetings that will begin Monday, Feb. 17
and run through Feb. 27 (for a list of those meetings, please see
the Outdoor Calendar on page 42 of this issue).

When it comes to evaluating the 15 or so factors that could have
played a role in setting up the 2002 deer harvest, Zeckmeister
noted that a wet fall probably played a role in suppressing the
archery harvest. So far, all of the talk around the drop in the bow
kill has blamed the baiting ban. Zeckmeister said that from Sept.
13 through the October Zone T opener, there were 39 days of rain at
two times the volume and three times the duration of an average
year.

“If you’re a conscientious bow hunter, do you shoot at a deer in
a steady rain? I think that contributed to the depressed archery
kill,” he said.

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