MagazineMarch 2011Glowing Eyes in the Dark

Glowing Eyes in the Dark

Bundled in the warmth of your sleeping bag as you drift into a slumber, you are startled by the coyote’s croon or the high whinny of the screech owl – animals out foraging for food and stalking their prey. Our Blue Ridge backyard is an ecosystem for a wide variety of nocturnal mammals, birds, and insects. The night life is a dynamic world in constant flux: migrating coyote populations are replacing the red wolf; bats are dying from a mysterious disease; and more mountain lion sightings suggest that large cats may still roam the mountains.

“Most mammals originated as nocturnal creatures, mainly to stay out of way of dinosaurs and reptiles,” says Doug Shedd, professor of biology at Randolph College. “Mammal species diversity exploded after the extinction of dinosaurs. But as a group, mammals still have a large number of nocturnal species. They rely on hearing and sense of smell rather than vision.”

Mammals such as skunks, foxes, coyotes and opossums, through evolution, have adapted a nocturnal nature, which is reflected in their senses, behaviors, and hunting strategies.

One of the most complex qualities nocturnal animals has is night vision. “Most mammals don’t see colors well. Most mammals don’t have good color vision or any at all. And that’s really the result of them using them for nocturnal situations,” Shedd says.

Nocturnal animals rely on rod cells, which are useful for seeing after dark, whereas cone cells—color vision—needs light and is only useful during the day. This is why humans lose much of their color vision after dark, because they rely on rod vision. Owls rely on rod vision to see well at night, allowing them to not need much light to hunt for their prey.

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