Study: Duck kill rate higher with spinners
And they don’t reduce the crippling
By Joe Albert Staff Writer
Bemidji, Minn. — A study in Minnesota on the vulnerability of
mallards to spinning-wing decoys has produced a mixed set of
results. On one hand, researchers, as expected, found that kill
rates are higher when spinners are used.
On the other hand, they found spinners don’t reduce crippling,
and don’t make it any easier for hunters to be selective in regards
to shooting drakes or hens – claims often advanced by spinner
“I was surprised it didn’t go at least a little bit toward what
people were saying,” said Mike Szymanski, who worked on the study
as a graduate student at Louisiana State University. He currently
is a migratory game bird biologist for the North Dakota Game and
Fish Department. “It basically went opposite of what people
Szymanski completed the study with Al Afton, of the Louisiana
Cooperative Fish and Wildlife Research Unit at LSU, in 2002. It
recently was published in the Wildlife Society Bulletin.
The study involved 219 experimental duck hunts in the 17
counties that between 1995 and 2000 produced the highest mallard
and total duck harvest in the state.
Results showed that mallard flocks (more than one duck) were
nearly three times more likely to to respond, and that those flocks
were about 1.25 times bigger, when spinners were turned on as
opposed to turned off. The number of mallards killed was nearly
five times as high when spinners were turned on.
The increased effectiveness of using spinners was “pretty
obvious going in,” Szymanski said. “It was almost a given.”
During the hunts, hunters killed 221 mallards (mallards totaled
43 percent of the total ducks killed during the experiment). Five
percent of the hunters killed a limit of mallards.
“Every study that’s evaluated them has shown that you shoot more
ducks when you have them on,” said Steve Cordts, DNR waterfowl
biologist. “So yes, you shoot more, but they are not magic, and
every time you stick one in the water doesn’t mean you are going to
shoot a limit of mallards.”
Perhaps as important as the increased harvest is the fact that,
according to the study, young birds are more vulnerable to spinners
than are adult birds. (Part of the study was to look at whether the
increased kill rates affect local breeding populations of mallards.
That part of the study continues, Afton said, but there’s not much
evidence of that at this point.)
“Decoys have been around a while now,” Szymanski said. “(Adults)
avoid them a little better, or don’t come screaming in as fast as
the hatch years do. The decoys are always going to maintain a fair
amount of effectiveness just because the hatch-year birds are
always going to be susceptible to them.”
But they’re unlikely to help hunters select drakes over hens, or
help reduce crippling.
“We found no evidence that drakes were relatively more likely
than were hens to be killed by volunteer hunters in Minnesota when
(spinning-wing decoys) were turned on,” according to the study.
“Thus, we conclude that use of (spinning-wing decoys) did not allow
hunters to better select drakes over hens.”
Despite the study’s results showing that kill rates were higher
when spinning-wing decoys were used, it’s still not clear how
spinners influence the continental population.
“A multi-year, flyway-wide study is needed to make stronger and
more rigorous inferences regarding potential changes in harvest
distribution and annual harvest rates of mallards due to increasing
use of (spinning-wing decoys) by hunters in North America,”
according to the study.
It’s unclear whether spinners redistribute harvest, or whether
ducks shot by hunters using spinners would have been shot anyway,
But ducks apparently learn to associate spinners with danger,
which could change harvest distribution – meaning more young ducks
are shot in the north, Afton said.
“After (spinning-wing decoys) caught on all over, they shied
away from them down here in my hunts,” Afton said.