Those who live in deer country are probably aware of deer whistles. They come in pairs and one is attached to each front side of the vehicle. They are supposed to emit a sound which repels deer. Some swear by them and it appears to me that deer may be on the side of the road but will not cross. Having said this, a large doe crossed the road in front of our car the other night but, in fairness, we had slowed and stopped the car when this happened. The whistles would have been rendered useless. Anyway, they are inexpensive and it can't hurt to install them on a car.