No they don't. I have a few friends that installed them on their cars or trucks and they still manage to get tangled up with a deer, dog, coyote, etc, etc,etc. If a dog can't hear them then a deer won't either.

 

Very Effective................at separating the gullible from their money.

 

They worked 50 years ago. since then evolution of species and several generations of deer have become immune to their effect.
very similar to kids and video games.

 

 

Yea they do if they're installed properly. I found out the hard way when I found myself being chased down by a herd of deer.

 

Do gremlin bells truly work?

 

 

Probably don't want to be without when the zombie apocalypse hits. I hear it's like garlic to vampires!

 

My bike came with both the wind whistle and an electronic whistle that is switch operated - definitely makes an annoying high pitched sound that you can only hear when at idle. The previopus owner paid over $100 for it, plus he paid for install. Not sure how effective it is, but there are a lot of deer around here, so maybe I will find out one day.