Any information on electrically powered deer whistles (rather than the passive kind)? They seem a bit expensive, but do they work? As I understand them, they are positioned under the hood and they emit a constant sound while the car is running.
If you were asking about the passive kind, I’d say there is no scientific evidence that they work, but if they’re cheap, they can’t hurt.
Since you’re asking about the expensive variety, I’d say ask whoever is selling them to provide unbiased peer-reviewed research for you to read and share with us.
Do they come with a warranty to repair damage caused while they’re in use, like my cell phone case does?
Given their research experience, the Georgia-based researchers concluded the following: “Considering the challenges of producing sound at appropriate intensities and distances from a moving vehicle, deer hearing capabilities, human safety concerns, and our observed lack of behavioral responses of deer to sound treatments, auditory deterrents do not appear to be appropriate for prevention of deer-vehicle collisions.”