Well, what the paper says is that deer can hear the low frequency ones (probably), but not the high frequency ones.  It also says that road noise may mask the whistle.  It does not say that they do or don't work.  My guess is that they don't stop deer from entering the road, even if deer do hear them.  After all, they almost certainly hear and see the vehicle.  When I hit a deer, the things were running around in a blind panic.  I had slowed to almost a crawl (annoying other drivers whom I guess just wanted to hit the deer anyway, they had to see them), and the deer had disappeared back into the woods.  I sped up, the deer came back and ran in front of me before I could stop.

mcneely

---- Stuart MacMillan <stuartmacm@GMAIL.COM> wrote: 
> Well, no they don’t then!   I conclude from this paper that constantly honking your horn is the only effective method to alert deer.  Not such a good idea in populated areas.
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> I watched this recent PBS program on deer overpopulation in NY, it’s a big problem:  http://video.pbs.org/video/2365000001/ 
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> Stuart
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> From: Alistair Bell [mailto:albell@shaw.ca] 
> Sent: Sunday, September 08, 2013 6:36 AM
> To: Stuart MacMillan
> Cc: vanagon@GERRY.VANAGON.COM
> Subject: Re: Deer whistles--do they work?
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> http://www.bioacoustics.uconn.edu/reports/ARLOManuscript326%20FINAL.pdf
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> Alistair

--
David McNeely