Why Do Fireflies Glow?

Wisdom, some wise guy once said, is its own reward. Well, call me a craven materialist, but I’d rather have the Reese’s Pieces. Let me explain. My hiking buddies and I like to pass time in camp trying to one-up each other with our “knowledge” of everything from backcountry diseases to astronomy. To make things interesting, we ante up whatever we find in our gorp bags:

raisins, peanuts, the usual. When the stakes get high, we pull out the Reese’s Pieces. On the fourth day of a six-day trek, those little buggers are worth more than any $100 casino chips.

So when I first started ferreting out the following fun nature facts, I couldn’t help but picture myself burdened with booty, cackling with peanut-butter breath at my ill-informed friends. But then my cravings gave way to something more satisfying: an appreciation for the mysteries of the wilderness we all cherish. I hope the questions and answers here do the same for you, making your next trip more enlightening, safer, and, yes, a little sweeter.

1. Can I eat bark?

“Sure you can, or at least the cambium layer just beneath the bark, but why would you?” asks Christopher Nyerges, author of In the Footsteps of Our Ancestors: Guide to Wild Foods. While the bark of trees such as alder, birch, and willow can be munched in an emergency, there are many wild foods far more palatable, Nyerges notes. The most readily available edibles include any type of grass or true cactus (not agave or century plant), any fresh seaweed, all members of the mustard family, and acorns after they are husked and boiled to remove the bitter tannic acid.

2. Why do birds fly in a “V”?

Like feathery stealth bombers, flocks fly in wedges for aerodynamic reasons, explains Karen Johnson, past president of the San Fernando Valley Audubon Society. Each bird-except for the leader-gains lift from the wing vortices of the bird in front. When the lead bird tires out, it switches places with a “wingman.” Formation flying may increase the range of a flock as much as 70 percent over that of a bird flying solo. Such V-flying may also allow birds to maintain visual contact and avoid collisions, Johnson adds.

3. Why do we need mosquitoes, blackflies, and other bothersome bugs?

“First, insects are one of the main sources of high-quality food for wildlife,” particularly fish and birds, says Lou Bjostad, professor of entomology at Colorado State University in Fort Collins. “Second, many biologists believe that a complex ecosystem including many species of plants and animals is a healthy ecosystem. Mosquitoes and blackflies are simply additional species.”

4. Does moss really grow on the north side of trees?

Very generally, yes, because moisture-loving moss avoids the heat of southern exposure. But never rely on moss to pinpoint direction; in cool or dark forests it’s common to find moss growing all the way around trees. Members of the sunflower family, such as the common, swamp, and prairie sunflowers, are somewhat more reliable. They follow Ol’ Sol across the sky, facing east in the morning, south at noon and west in the afternoon.

5. How can owls fly silently and hunt in the dark?

Owls are adapted perfectly to operate after hours. According to Dr. Wes Stone of the Cooperative Wildlife Research Laboratory in Carbondale, Illinois, owls swoop silently because their wing tips are slotted and the leading edges of their flight feathers are serrated. These features disrupt air flow and eliminate noisy wind patterns. Owls hunt effectively at night because their concave face feathers channel sounds to their ears so they can track sounds. Owl eyes also have more rods than cones, enabling them to see in the faintest light.

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.

13. What’s munching on my boots and canoe paddles during the night?

Deer, mice, marmots, and porcupines are attracted to salt deposits, including dried sweat on gear and clothing. Another source that will attract wildlife is the salt left after urine has evaporated. So avoid doing your business on delicate plantlife, especially in alpine areas where salt-seeking goats, sheep, or deer may chew plants and paw the ground to get at the salt.

14. Why do animals migrate?

For the same primal reason you drive straight to your favorite pizza joint after a week on the trail: “basically to follow food sources and the other amenities of life,” explains Fellows. “They make maximum use of their habitat by going to where they can obtain the requirements of survival and reproduction.” Annual migrations can be measured in hundreds of yards (bighorn sheep moving down from subalpine zones in winter) or tens of thousands of miles (arctic terns winging 20,000 miles between polar regions).

15. Is there a natural bug repellent?

According to Bjostad, nothing found trailside is as effective as that old standby N, N-diethylmetatoluamide, or DEET. Some folks swear by oil of citronella, which can be purchased commercially. The only organic bug-beater found in the backcountry is mud.

16. How do I get rid of skunk odor?

The best way to eliminate the funk is to avoid skunks altogether. But if you do get sprayed, washing clothes and gear in a diluted solution of an off-the-shelf douche preparation will do the trick, swears Dave Fellows, a wildlife biologist at the Northern Prairie Wildlife Research Center in Jamestown, North Dakota. The staff there even washes their trucks with it. (Wouldn’t you love to see the expression on the checker at that grocery store.) How about tomato juice? That solution is only temporary at best, Fellows says.

17. And how can I tell when a skunk is agitated enough to spray?

Skunks only spray when surprised or cornered, offers Marsha Sovada, a wildlife biologist at the Northern Prairie Wildlife Research Center, so give them a wide berth. If you are caught between a skunk and a hard place, the animal will first raise its tail. Some skunks will also stamp their front feet before letting loose.

18. Can a porcupine throw its quills?

That’s a myth, Dr. Stone says. “Despite all the stories, a porcupine’s quills are firmly attached. They can, however, erect their quills by muscular contraction, similar to piloerection (goose flesh) in humans when skin gets cold. A naive dog may come home with quills stuck in his nose, but that’s from direct contact, not an airborne assault.”

19. What are those coyotes howling at?

One reason coyotes howl “is to announce their presence in a territory to other animals,” says Dr. Stone. “In this way they can avoid potentially lethal confrontations and secure exclusive rights to the resources in that territory.” They also bay to indicate their social rank within a pack or to communicate danger from predators such as cougars or wolves.

20. How do I tell the difference between a black bear and a grizzly?

You certainly can’t tell by color, because “black” bear hues range from charcoal to cinnamon. If you’re anywhere outside of Canada, Alaska, Colorado, Montana, Wyoming, and Idaho, you’re most likely out of griz country. But just in case, grizzlies (and their cousins, brown or Kodiak bears) are usually significantly larger, boast a pronounced shoulder hump, and have larger ears and long claws.

21. How can crickets tell the temperature, and what other creatures are weather forecasters?

The Weather Channel is more reliable than any critter, but the male snowy tree cricket (Oecanthus fultoni), found in all United States regions except the Southeast, does vary its chirping according to the temperature. Adding 40 to the number of chirps made in 15 seconds provides a close measure of the temperature in degrees Fahrenheit. Evidence is spotty for other creatures, but owls hooting throughout an autumn night are said to be harbingers of a storm, waterfowl usually fly higher in clear weather and lower in stormy weather, and woolly bear caterpillars are supposedly blacker before severe winters.

22. What do tree rings mean, and how do I count them?

In temperate zones, including North America, most trees add a ring every year, making a tree the only organism whose age can be precisely determined. Tree rings enable scientists called dendrochronologists to not only date specimens, but also “interpret how these trees have been treated by mother nature and human activity,” explains Dr. D.W. Larson, a professor of botany at Guelph University in Ontario, Canada. “Each of these long chronologies, as they are called, is a living clock whose ticks are louder or softer as a function of drought, cold, heat, and disturbance.” Certain tree species’ rings are easily identifiable, such as oak, ash, hickory, tamarack, fir, or northern white cedar. Each annual ring actually consists of two rings: a light-colored ring (earlywood) and a dark-colored ring (latewood).

23. Can snakes spit venom?

Yes, but thankfully not the ones in this hemisphere, Fellows says. The spitting cobras of Africa have a propensity for defending themselves by squirting a thin stream of venom toward the eyes of an attacker.

24. Why do leaves change color?

The green pigments known as chlorophyll, which capture energy from the sun, dissipate as the days grow shorter and the nights colder. This lets the yellow, brown, and orange pigments, called carotenoids, already present in the leaf shine through. Red and purple come from anthocyanin pigments, which are produced in sap cells beginning in late summer.

25. Do opossums really play dead or hang by their tails?

They’ll play “possum” when confronted by an aggressor and are known to secrete a foul-smelling substance like skunks do. As for hanging, young ones do but mature opossums are unable to support themselves by their tails, although they use them while climbing.

Matt Purdue hoards his Reese’s Pieces in the Southern California backcountry.