Postby Steel 3's » Tue Mar 22, 2005 9:52 am
The study is flawed. They should have removed the SWD from the spread when off.
All controlled studies are flawed to some extent. None of us change something in our hunting back and forth with the clock; that's not realistic. But a scientific study does so (and accepts the loss of "reality") to control for the effect of other factors like weather that day, duck populations in the area, hunter-quality, etc. Ideally, they want everything to be exactly the same except for the effect they are testing ..... in this case, the spinning wings. Besides the logistical problem of pulling the SWD and replacing it at 15-minute intervals, by doing so you confound the effect of the spinning wings by changing another aspect of the decoy spread at the same time.
Another way to do this type of study is to make entire hunts either with or without the SWD. Because you then inject LOTS of variation in all the other aspects of the hunt, you have to make many, many more hunts so that the variation due to the other factors is "averaged out", and you can see the effect of the SWD. The methods used in this study are clearly more cost-effective.
Someone asked about the position of the wings when the spinner was "off"; the authors say "During the control periods we turned off and adjusted the wings to the horizontal position with the white side facing down".
A motionless bird suspended two to three feet above the water is going to flare birds, increase cripple ratio, and decrease close shots.
Decoys simulating flying birds have been sold and used for decades. I've not seen anything as definitive as you state. If what you say is true, then remote-controls or variable functions (regular on and off) on SWDs would be counter-productive because anytime they are "off" they are flaring birds. However, I've seen numerous testimonies to the contrary.
The Kill/wound ratio and the range/no range ratios follow each other hand in hand.
I'm not sure what you mean by "hand in hand". For MARSH hunts, the probability of a mallard coming within range (40 meters) is 1.9 times higher with the spinner on and the crippling rate is 1.7 times lower. However, there was NO difference in crippling in early-season FIELD hunts despite mallards being 6.4 times as likely to come in range. Even in the late-season FIELD hunts, the crippling rate was only 3.7 times lower with the spinner "on", which IMO is not "hand in hand" with the 6.4 time greater probability of a mallard coming in gunning range.
The most interesting statement in this report is that there was no dicerrnable difference in body mass.
Where did you read that? What the researchers tested was if the "body condition" of the birds killed was different with spinner "on" vs "off" ..... and they were different. Mallards killed with the spinner "on" were in better condition, on average, than those killed with the spinner "off".
The reason we use a condition index instead of just body mass is because a larger bird (larger skeletal size and volume) in poor condition (little body fat, atrophied muscle) can have the same mass as a smaller bird that is in much better condition.
As the authors themselves have concluded, this study is not the end-all to the SWD debate. It's a solid piece of work, but it's mostly the information on crippling rates and body condition that make it noteworthy IMO.