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Fall 2009

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Wild Watch

view of lake shore during spring time
Photo by Bob Steiner

by Heidi Mullendore

I shivered as the cool night air swirled in through the windows of the car. The warm autumn days were ending in chilly nights, and frost was transforming green fields into the muted browns and golds of autumn.

I was driving home along a lonely country road, my mind on the day’s events. Suddenly, several brown shapes stepped from the foliage. My headlights caught the yellow-green eyeshine of deer, as they fed by the side of the road. I slowed the car to a crawl, as a doe and her fawns picked their way carefully across the road, their eyes glowing eerily in the headlights.

Late summer and early fall, with its abundance of food and cover, is a busy time for many hunters across the state. They start scouting for the upcoming seasons. Their camouflage clothing comes out of storage, along with their hunting equipment and spotlights. The gist of the sacred sport (never call it a hobby!) of scouting by spotlighting is to pile into the truck on a chilly autumn night and drive around to search for deer, using a powerful spotlight.

racoon
Photo by Bob Steiner

Caught in th ecamera's flash, a night-roaming raccoon shows it can be a predator, because both of its eyes shine at the same time. Raccoons, like most predators have binocular vision. Prey animals' eyes are located on the sides of their head, so they generally show single-eye eyeshine.

Even if you've never been spotlighting, you've probably experienced the heart-stopping moment of coming around a curve at night and your headlights startling some deer crossing the road. The yellow-green eyeshine of deer after dark is familiar to most Pennsylvanians. Seeing eyes glowing in the dark sparks many emotions, but as spooky and mysterious as eyeshine may seem, the science behind the shine provides us with some interesting insights into the nocturnal world.

Our eyes contain specialized light-receptors, called rods and cones. Cones allow us to see color and sharp detail. Cones function well in the bright light of aytime, the reason that humans are diurnal, or daytime, animals. Rods, on the other hand, function well in dim light conditions and aid in light gathering and seeing motion. As evening descends and the amount of light available diminishes, the color vision that humans enjoy during the day recedes and we see things only in black, white and shades of gray. Nocturnal animals have many times more rods than cones, and thus do not have color vision. After sundown, deer and many other animals have a distinct advantage in low-light conditions, as the moon and stars provide enough light to allow nocturnal animals to navigate with ease.

The doe in front of my car lowered her head and stomped her foot. Her eyes glowed eerily in the headlights. With a quick snort, she and the fawns
abruptly leapt off the road and into the trees. For a few seconds, I could hear them running through the woods in the blackness. Trying to coax my heartbeat back to normal, I drove on carefully, looking for the telltale eyeshine of various night critters that can make afterdark driving on back roads an obstacle course.

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Pennsylvania Wild Resource Program