Here is the study that led to the CBS story:
Effects of Spinning-wing Decoys on Flock Behavior and Hunting Vulnerability
of Mallards in Minnesota
Alan D. Afton, U.S. Geological Survey-Louisiana Cooperative Fish and
Wildlife Research Unit, Louisiana State University, Baton Rouge, LA 70803;
225-578-4212; FAX 225-578-4227;
aafton@lsu.edu
Michael L. Szymanski, School of Renewable Natural Resources, Louisiana State
University, Baton Rouge, LA 70803; 225-578-5747; FAX 225-578-4227;
mszyma1@lsu.edu
Waterfowl managers in Minnesota and other states are concerned that
increased kill rates associated with the use of spinning-wing decoys ,SWDs,
may negatively affect local breeding populations of mallards. We conducted
219 experimental hunts to evaluate the hunting vulnerability of mallards to
SWDs during the 2002 duck hunting season in Minnesota. We placed 2 SWDs
within traditional decoy sets of 367 volunteer hunters and turned SWDs 'ON'
or 'OFF' during alternating 15 minute sampling periods within each hunt.
Mallard flocks were 2.68 times more likely to respond i.e., flew
within 40 m of hunters, to decoy sets when SWDs were turned 'ON' than 'OFF'.
Additionally, size of responding mallard flocks was 1.30 times larger when
SWDs were turned 'ON' than 'OFF'. Mallards killed per hour per hunter per hunt was
4.38 times higher, which is significant statistically, when SWDs were turned 'ON' than 'OFF'. However,
mallards killed per hour per hunter per hunt were similar, which is not significant statistically, between the
first and second halves of the duck hunting season, regardless of SWD
treatment. Despite increased kill rates when SWDs were turned 'ON', less
than 6% of volunteer hunters actually achieved daily bag limits of mallards
during experimental hunts. Finally, we are using stable isotope analysis to
identify local hatch-year mallards that were shot during experimental hunts
and will discuss management implications regarding effects of SWDs on local
breeding mallards in Minnesota.