Originally Posted by
Bob Ross
I've never heard of an ultrasonic deer whistle; every deer call device I've ever heard* sounded like a bullfrog croak, low, guttural, and well in the human audible range. If you strapped one on your bike such that it would be constantly activated by your movement-generated wind, it would sound like the bean scene from "Blazing Saddles"
*I worked with a woodwind player for decades who gradually transitioned away from instruments in the saxophone and clarinet family to almost exclusively game calls. He would show up to gigs with 4 or 5 deer calls, a half dozen duck calls, crow calls, and a few outliers designed to attract several other game or varmint species. I got real familiar with the sound of rutting deer...such that the one or two times I've heard that while cycling, I've stopped until I could confirm the deer weren't crossing the road anytime soon.
No no, you don't want to *attract* deer, you just want them to be able to *hear you*. Any noise, the more repellant to them the better. But hopefully something inaudible to humans so not annoying. Like I said, the ones I had seen on other vehicles were mounted on the front bumper, so even something audible might be hidden from the car passengers by the engine noise; When electric vehicles came into being (first modern one being the GM EV1), suddenly, sounds that were previously masked by the engine, became a huge annoyance to drivers and passengers, and there was tons of work to make cars quieter. On a bike, anything audible will be heard. So I don't know if deer can hear anything outside of normal human hearing frequency range. Ah, info online:
https://en.wikipedia.org/wiki/Deer_horn
Executive summary: Nope, don't work.