THOSE GLOWING EYES: The Story of Eye Shine

You are driving after dark and there just in the bushes at the side of the road are a pair of eyes, glowing in the darkness, looking for all the world like two floating alien orbs.  What on earth (or not of this earth), causes eyes to shine like this? Many nocturnal animals have a mirror-like layer in the retina that reflects light. It is called the tapetum lucidum (meaning “bright carpet”). This layer gives the visual pigments a second chance to absorb the light and serves to improve vision in low light. When a flashlight or a car’s headlights shine light on the tapetum, it is mirrored back to our eyes in a variety of interesting colours. 

Humans don’t have a tapetum lucidum.  But you may have noticed that red-eye effect in some photographs.  This can happen when a bright flash from a camera, lights up the vessels in the back of the eye which are rich in blood vessels.

If you want to see these mysterious glowing eyes of animals, take a leisurely drive along back roads that wind through different habitat types such as wetlands, fields and woods. Remember to watch for animals that may be crossing the road well ahead of the car. It can also be worthwhile to stop the vehicle and sit quietly in an area where two habitat types come together, such as a field and a woodlot. Use the binoculars to scan distant field edges. Watch especially for the luminous eye reflections of mammals along the roadside, where some species scavenge for roadkill.  Try to identify the animal by noting the colour of its eye shine. The colour varies from species to species and on the angle at which the eyes are seen. Here is a quick field guide to eye shine colour.

Submitted by Jacob Rodenburg, Author & Executive Director of Camp Kawartha, an award-winning outdoor education centre and summer camp.