The Pennsylvania Game Commission has issued an advisory for motorists to slow down and stay alert due to the deer becoming increasingly active. Daylight saving time ending on Saturday caused an increase in vehicular traffic between dusk and dawn, which coincides with the peak hours for deer activity.

Deer become more active in autumn with the lead-up to their fall breeding season, which is commonly referred to as the rut. About this time of the year, many yearling bucks disperse from the areas where they were born and travel, sometimes several dozen miles, to find new ranges. Adult bucks are often cruising their home ranges in search of does. If a doe is encountered, the buck will sometimes chase the doe.

While I am driving, Mary Alice often reads or does crossword puzzles, however at night while heading home on Route 14, she is always on watch for a deer that could be in the road or alongside the road.

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 green-gold, opossums have dull orange, skunks have amber and foxes have white. I never read the following in a book or magazine, but an old raccoon hunter once 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.

Most nocturnal animals have a keen sense of hearing, touch, smell and this nighttime vision. There are some animals, such as the bat with its radar hunting, that have extra abilities. The great-horned owl uses its ears to find prey. This owl’s ears are in the facial disk, with one ear located higher on the head than the other. The great-horned owl must turn its head until both ears are picking up the same decibel of sound.

At this exact moment, the owl will be looking at what is making the noise and able to see its prey.

Nocturnal animals use the same space and eat the same food as diurnal 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 other insects.

Some animals such as mice and voles, 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 predators. Hawks search for rodents and small mammals during the day and at night the owls take over the hunt.

Most daytime animals including humans 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 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 have all heard someone say “they had the deer in the headlights” look. This describes a person so stunned they are unable to move, with eyes wide open and 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. 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.

As a wildlife officer I spent many nights 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 I occasionally 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.

Humans have copied this nighttime eye shine occurring in animals by making reflectors that shine when a light is cast upon them to aid us in driving safely at night. Just one of many things we have copied from wildlife.

Bill Bower is a retired Pennsylvania Game Commission Wildlife Officer. Read his blog and listen to his podcasts on the outdoors at www.onemaningreen.com.