All nocturnal animals have what is called eye-shine, caused by tapetum lucidum, a Latin word meaning bright tapestry. This tapetum lucidum, which lies behind the retina, reflects light back through the retina, increasing an animal’s superior night vision. When an artificial light hits an animal’s eyes, the eyes appear to glow.
Although deer have a yellow-eye shine, dogs and cats have a green eye shine; coyotes have a green-gold eye shine; opossums have a dull orange eye shine; skunks have an amber eye shine and foxes have a white eye shine. An old coon hunter told me that a male raccoon’s eyes have a red glow, while the female’s eyes have a yellow glow. He went on to say that this includes only adults.
Nocturnal animals use the same space and eat the same food as diurnal (daytime) animals. During the day, birds that eat insects will feed upon the butterflies sipping nectar. At night, the nightjar family (whip-poor-wills and night hawks) will feed upon moths that are sipping nectar and also other insects.
Some animals (mice, voles, etc.) are nocturnal, not because they can see better at night but because they feel safer, and, to a greater extent, these animals are hidden from the predators. Hawks search for rodents and small mammals during the day, and at night, the owls take over the hunt.
Most daytime animals, including man, do not have this tapetum lucidum; therefore, our night vision is mediocre compared to those animals that are active at night. Our night vision does increase when we are in an area of total darkness. After about 30 minutes in the darkness, a person will have their optimum night vision; however, if a flashlight is turned on or a cigarette lit, our night vision will become limited. The U.S. Army states that it takes 30 minutes for a person to regain their best night vision.
When a flash is used to take a photograph the eyes of the person in the photograph could appear red. Since we humans have no tapetum in our eyes, this red eye occurs when the flash illuminates the blood vessels in the back of our eyes. If the source of the flash is something other than that of a camera’s flash, there will be no red eye.
I’m sure you’ve heard someone say “they had the deer in the headlights’ look”. This saying describes a person being so stunned they are unable to move; have wide opened eyes and are at a loss for words. A light shining on a deer’s eyes at night causes the deer to become confused, with images blurred. Often the deer just stands there. However, if the deer runs away after having the light shine on its eyes, the night vision immediately returns.
It is illegal to go hunting deer at night with a light. Here, in Pennsylvania, we call this jacklighting. This term originated back in colonial times when people went deer hunting at night. Since there were no flashlights, the hunters lit baskets of jack pine knots, which burned brighter and longer than other pine knots; hence, the term jacklighting. As a wildlife officer I spent many a night watching in areas for spotlights crossing the sky. Most of the time the flashes in the sky were simply families out spotlighting for deer; however, once in awhile I caught a jacklighter and an arrest was made.
Animals are not the only creatures that have eye shine. There are fish, especially walleyes, that have white eye shine; some species of spiders have eye shine; however, this eye shine is not the result of tapetum lucidum.
Man has copied this night time eye shine occurring in animals when making reflectors that shine when a light is cast upon them to aid us in driving safely at night.