What might indicate a deer is close to the road?

The presence of headlights reflecting off a deer's eyes is a strong indicator that a deer may be close to the road. When caught in the beam of headlights at night, the eyes of deer tend to reflect light and appear to glow. This phenomenon is due to the tapetum lucidum, a layer of cells behind the retina that enhances their night vision by reflecting light back through the retina. Drivers should be particularly cautious when they see such reflections, as it is a visual cue that deer may be nearby, potentially crossing the road.

While things like noise, tracks, and the time of day can provide some information about deer activity, none are as immediate and visually striking as the reflection of light from their eyes. Noises can be misleading, tracks may not be visible to all drivers, and daylight doesn't necessarily imply that deer are absent from the area—many deer are active during the day as well. This makes the reflection off their eyes a critical warning sign for drivers to be alert and ready to react.