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May 1998

Why Do Fireflies Glow?

Plus 24 other round-the-campfire brain stumpers every nature buff should know.

6. How and why do fireflies glow?

Fireflies glow when a substance called luciferin mixes with the enzyme luciferase in the tips of their abdomens. Why? Two reasons, explains CSU’s Bjostad. First, fireflies contain a toxic chemical, so flashing serves as a warning to predators. Second, they glow to attract mates. Interestingly, each species of firefly has a specific flash pattern, so some predatory female fireflies are known to mimic the flashes of other species to attract males to…ahem…private dinner parties.

7. How can you tell direction without a compass?

Stand a 3-foot stick in the ground where it will cast a shadow. Mark the end of the shadow with a rock. After the shadow moves, mark the new end with another rock. A straight line drawn between the two rocks runs east-west, the first rock marking west. Draw the shortest line between the stick and the east-west line to mark north-south.

8. Is there a universal bird call?

No, says the Audubon Society’s Johnson. However, some birders swear by “pish, pish, pish” to lure many varieties of birds, such as the song sparrow and common yellowthroat. “This imitates the alarm calls of certain species, which may come into view out of curiosity or a desire to chase away a potential predator.”

9. Why do stars twinkle?

They don’t. Sorry all you romantics, but from our vantage point on Earth stars only appear to glint and glimmer because their light is refracted through hot and cold air in our atmosphere. When viewed from space, stars are steady points of light.

10. How do I know if a snake is poisonous?

In North America, there are four species of venomous snakes, three of which are pit vipers. All of these pit vipers-rattlesnakes, water moccasins, and copperheads-have relatively large, triangular heads. They also have elliptical irises, but if you can tell that, you’re too close. North America’s other poisonous snake is the coral snake, easily identified by red stripes next to yellow stripes. The harmless king snake has red stripes next to black, which is the origin of the saying, “Red on black, friend of Jack (or “venom lack”); red on yellow, kill a fellow.”

11. Do bears really sleep all winter?

No, bears are not true hibernators like bats and ground squirrels, reports Dr. Stone. “They often wake up in the winter to briefly prowl around, feed cubs, drink water, or feed themselves.”

12. What do I do if I encounter a mountain lion?

“Give the lion plenty of room to get away from you. Do not run,” urges Lynn Sadler, executive director of the Mountain Lion Foundation in Sacramento, California. “Do not bend over. Stand your ground and appear as unlike prey as possible. Spread your coattails, hold your hands over your head, speak sternly, throw something. If you are attacked, fight back with anything and everything you have. Lions rely upon surprise and are not known for their stamina.” (This is contrary to a grizzly attack, when you should cover your neck, play dead and stay as still as possible after the bear has signaled its unfriendly intentions by charging or attacking.) Sadler notes that small adults running alone and children are most vulnerable to mountain lions. Bear in mind, of course, that sightings of North America’s largest cat are still extremely rare.

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