connect: Find us on Facebook Follow us on Twitter Follow Dot the Otter on Twitter Follow us on Instagram SeeTucson Read about us on Trip Advisor

Desert Questions and Answers

Book of Answers

Excerpts from the Arizona-Sonora Desert Museum Book of Answers

GETTING TO KNOW THE DESERT

AROUND THE HOME

ENJOYING THE OUTDOORS


What exactly is a desert?

A place where lack of water is severely limiting to living things most of the time.

Depending on who's counting, there are about twenty major deserts on our planet, each a unique and fascinating world in itself, and it's no easy task to find one description that fits them all. The deceptively simple definition above is as good as any, and it has much to say about what a desert is. But let's start with what it doesn't say.

First, it says nothing about what a desert looks like. For many of us, the word "desert" calls to mind expanses of sun-baked sand dunes, but the world's deserts also encompass barren salt flats, snow-swept plateaus, fog-cloaked coastal plains, cactus-studded mountains, and a great many other distinctive and beautiful landscapes besides.

Second, and perhaps more surprisingly, the definition says nothing about heat. Freezing temperatures are actually commonplace in many deserts, especially those far from the equator and the ameliorating effects of oceans--for example the deserts of Central Asia and our own Great Basin Desert. At the chilliest extreme are the polar deserts of Antarctica and Greenland, where the frigid air can hold scant moisture, and what little precipitation there is comes in frozen form.

So what do all deserts have in common? The definition has the answer: aridity. A desert is a dry place, not necessarily a hot one (though heat is one way to make a desert dry). It's a place where plants, animals, and human beings have adapted to--even thrive in--an environment where water is usually scarce and its arrival almost always unpredictable.


Other questions and answers in this chapter:


Are there seasons in the Sonoran Desert?

Yes, but they're quite different from the seasons in temperate climates.

So different, in fact, that naturalists don't all agree on what to call them, when they begin and end, or even how many there are! The situation is complicated by the unpredictability of desert rainfall, which profoundly affects both the timing and the character of every season. The Desert Museum recognizes five seasons in its surroundings in the Arizona Upland. How many do you count?

Spring: February to April
Foresummer or dry summer: May and June
Summer monsoon: July to mid-September
Fall: Mid-September to November
Winter: December and January


Other questions and answers in this chapter:


How can I tell cacti from other spiny desert plants?

The surest way is by their flowers.

Colloquially, almost any spiny, thorny, or prickly desert plant is likely to be called a "cactus," but scientifically speaking only members of the botanical family Cactaceae truly deserve the name. Botanists group related plants in families largely by the structures of their reproductive parts; for flowering plants this means the design of their flowers.

This habit of botanists works well because of a peculiarity of plant evolution. When many species of plants evolve from a common ancestor their above-ground growing parts--stems and leaves--often diverge widely in appearance, but their reproductive parts tend to remain remarkably similar. You might never guess that a strawberry plant is related to a pear tree, but their flowers tell us they're cousins. (Both belong to the rose family.)

Fortunately, flowers in the cactus family are easy to recognize. Here are some of their more distinctive characteristics.

  1. Many sepals and petals, grading into each other. In many other kinds of flowers there are a few green sepals that cover the closed bud then open to reveal a few colorful petals. In cacti there are many of both, and you can't always tell which is which.
  2. Numerous stamens. Stamens are the male, pollen-bearing parts of a flower. Cactus flowers have too many to easily count--usually hundreds--crowded together inside the cup formed by the petals and sepals.
  3. Several stigmas. Stigmas are the sticky flower parts that receive pollen during pollination. In cactus flowers there are three to twenty stigmas, often forming a miniature starbust at the top of an elongated structure (a style) that rises through the forest of stamens.
  4. Inferior ovary. This has nothing to do with the quality of the flower's female parts! It's just a botanist's way of saying that the part of the flower that eventually turns into the fruit is sunk below the petals and sepals rather than sitting above them, as in many other flowers.

Other questions and answers in this chapter:
Which parts are which? - Saguaro flower diagram
What if the plant doesn't have any flowers?
Prickly Characters: tips on recognizing particular cacti

Elsewhere in the Book of Answers:
Which Sonoran Desert plants are most often mistaken for cacti?
Old World look-alikes and convergent evolution

The Book of Answers is available online from ASDM Press.


How old do desert plants get?
In most cases we can only make an educated guess.

Botanists have little firm information about the maximum ages of desert plants growing in the wild, but they've combined precious bits of hard data with casual observations, anecdotes, tantalizing clues, and a healthy dose of scientific intuition to come up with some reasonable estimates. The list below gives those estimates for a few common desert plants. Some of these numbers are much more secure than others, but each one deserves its question mark.

You'll have to decide for yourself whether or not to think of some of these plants as truly old. Take the saguaro for example. (Its maximum age is better established than most of the others in the table.) Compared to the human lifespan, two hundred years is surely a long time, and it may seem like a surprisingly ripe old age for a cactus. But at two centuries a bristlecone pine would be just getting started--some are more than four thousand years old!

People are naturally curious about the oldest desert plants, but species at the other end of the lifespan spectrum are interesting, too. Many desert annual wildflowers sprout, bloom, drop their seeds and die during a single rainy season. Some complete their life cycle within a few weeks, an abbreviated existence that earns them the name ephemerals.

One of the marvelous things about the Sonoran Desert is that despite its seemingly harsh climate there can be so many life strategies that work, and a tiny ephemeral wildflower can dash through its life in the shadow of an ancient ironwood tree.

Estimated maximum ages of some Sonoran Desert plants

Engelmann prickly pear (Opuntia phaeacantha var. discata) 30+
Triangle-Leaf Bursage (Ambrosia deltoidea) 40
Golden agave (Agave chrysantha) 50
Teddy bear cholla (Opuntia bigelovii) 60+
Fishhook barrel cactus (Ferocactus wislizeni) 130+
Catclaw acacia (Acacia greggii) 130+
Ocotillo (Fouquieria splendens) 200
Saguaro (Carnegiea gigantea) 200+
Foothill paloverde (Cercidium microphyllum) 200+
Ironwood (Olneya tesota) 800+
Creosote bush (Larrea tridentata) 12,000?
Boojum (Fouquieria columnaris) 100+
Cochal (Myrtillocactus cochal) 30
Blue palo verde (Cercidium floridum) 40-50
Pitaya agria (Stenocereus gummosus) several centuries
Baja elephant tree (Pachycormus discolor) several centuries
Creeping devil (Stenocereus eruca) each stem is potentially immortal
Desert agave (Agave deserti) clonal colonies - millennia (as long as habitat is stable); each rosette 50+ years

Other questions and answers in this chapter:
Why don't we know more about the maximum ages of desert plants?
Queen Clone? Can a creosote bush really live twelve thousand years?

Are saguaros endangered?
No, saguaros aren't threatened by extinction.

To paraphrase Mark Twain, reports of the saguaro's demise are exaggerated! Unfortunately, there have been enough "vanishing saguaro" scares over the years to give many people the wrong idea.

Scare number one. About 1940 a plant pathologist reported that many saguaros in Arizona, including a fifth of those in the famous Cactus Forest of Saguaro National Monument, east of Tucson (now part of Saguaro National Park), showed obvious signs of decay. A bacterium in the blackened and oozing tissues was soon identified as the pathogen of a deadly "bacterial necrosis disease." Rotting saguaros in the Monument were cut down in a "disease control" experiment, cacti were injected with penicillin, and it was even proposed that the entire Cactus Forest be sprayed with DDT to kill insects suspected of spreading the affliction!

False alarm. Bacterial necrosis is now thought to be just the natural decay of cactus tissues killed or weakened by something else, and few scientists still call it a disease. Saguaros, especially the very old and very young, are sensitive to subfreezing temperatures, and the "outbreak" in the Cactus Forest probably stemmed from a severe frost a few years earlier. Nevertheless, the myth of an insidious cactus plague lives stubbornly on.

Scare number two. As many spectacular older saguaros in the Cactus Forest succumbed to freezing and other natural causes, it became painfully evident that there were few young cacti to grow up and take their place. Concern grew about a possible breakdown in saguaro reproduction, and after the 1960s it focused on the apparent decline in southern Arizona of a saguaro pollinator, the lesser long-nosed bat (Leptonycteris curasoae). Partly as a result of fears for the future of the saguaro, the bat was listed as endangered in 1988.

False alarm. Saguaro flowers unfold long after dark and stay open until the next afternoon. Nectar-feeding bats do pollinate them at night, but after sunrise they're visited by a host of other pollinators, including honey bees (an Old World introduction), native insects, and birds. Bats are wonderful creatures, but saguaros would presumably go on making more saguaros without them.

(Other factors probably accounted for the missing juveniles in the Cactus Forest--see later in this chapter. Young cacti have made a comeback there in recent decades.)

Scare number three. In the early 1990s researchers called attention to a degeneration of the skin (epidermis) of some saguaros at Saguaro National Monument. Air pollution from nearby Tucson was first proposed as a cause of this "epidermal browning," then sunburning by ultraviolet rays--the hypothetical consequence of a world-wide thinning of the ozone layer. The phenomenon was quickly connected with the by then well-publicized decline of the Cactus Forest, once again raising the specter of the saguaro's imminent demise.

False alarm. The jury is still out on the causes of epidermal browning--it may just be the result of heat, drought, and old age--but there's no evidence that it by itself causes death or reproductive failure. Like bacterial necrosis, epidermal browning is a widespread natural process, and nothing new. It may make some saguaros less photogenic, but it won't make them all disappear.


Other questions and answers in this chapter:
Aren't there any real threats to saguaros?
Why so many false alarms about saguaros?

The Book of Answers is available online from ASDM Press.


What are the frogs I hear at night during the summer rains?
They may be spadefoot toads.

If they are, you have a chance to meet one of the Sonoran Desert's most remarkable creatures! Spadefoot toads, or just "spadefoots" for short, are toadlike amphibians, but technically not really toads. True toads are members of the zoological family Bufonidae, but spadefoots belong to the family Pelobatidae.

Actually, it's possible you're hearing true toads, not spadefoots. Further investigation is in order.

How can I tell whether they're spadefoots or true toads?

The very first night you hear them calling, grab a flashlight and head for the sound. There will be more out there than you and the amphibians, so watch for rattlesnakes. You'll probably end up at a temporary rain pond.

Now the real fun begins. You have to catch one. If you had a deprived childhood and never learned frog-catching skills, this may take a while. Hint: sometimes it helps to shine your flashlight in their faces.

Once you have the squirming, slippery creature firmly (but gently) in hand, look at its eyes. True toads have horizontal pupils, but spadefoots have vertical pupils (like cats). Then look behind the eyes. Toads have a raised poison gland behind each eye; spadefoots don't.


Other questions and answers in this chapter:
How can I tell the species?
Why are spadefoots so noisy?
How do spadefoot tadpoles grow up so fast?
Night music - can you identify the different spadefoot toads by sound?

The Book of Answers is available online from ASDM Press.


Is a javelina a pig?
No, javelina and pigs are members of different zoological families.

The javelina, or collared peccary, is one of three members of the peccary family (Tayassuidae). True pigs, including about nine wild species, belong to the Old World swine family (Suidae). The familiar barnyard pig is a domesticated form of one member of the Old World swine family, the wild boar.

(To be fair, though, many people--including some scientists--use the word "pig" for members of both families. The Desert Museum prefers to reserve that word for the Old world swine, which differ from peccaries in many interesting ways, as we shall see.)

If javelina aren't pigs, then why do they look like pigs?

Javelina resemble pigs for essentially the same reason people resemble their cousins: they have common ancestors. However, the last common ancestors of pigs and peccaries lived tens of millions of years ago, early in the Age of Mammals (Cenozoic Era). By about thirty million years ago pigs and peccaries were already trotting down separate evolutionary paths. How closely are pigs and peccaries related? To put it in perspective, the human family (Hominidae) and the ape family (Pongidae) had common ancestors much more recently--well within the last ten million years. By that standard pigs and peccaries are considerably more distantly related than people and chimpanzees!


Other questions and answers in this chapter:
How are javelina different from pigs?
Are javelina dangerous?
Peccary Perfume?
Are javelina really nearly blind?

The Book of Answers is available online from ASDM Press.


Do I need to water native desert plants?
After native desert shrubs, trees, and succulents have become established in a landscape, they ordinarily don't need watering.

But there are certain situations in which you may want to irrigate:

*When desert landscapes are planted more densely than natural desert plant communities--and they very often are--rainfall may not be enough to support them. You'll probably need to do some supplementary watering.

If an artificial desert landscape were an exact copy of the area's natural plant community, you'd never have to water it. The need for irrigation arises when we ask more from an arid land than it's ordinarily able to provide.
Other questions and answers in this chapter:
Is it possible to over-water native desert plants?
What about winter annual wildflowers?
Life on the dry side - How have desert plants adapted?

The Book of Answers is available online from ASDM Press.


How should I transplant cacti?
With a few exceptions, transplanting a cactus isn't much different from transplanting any other plant.

Cacti are tough. Often it's enough simply to stick one in the ground and leave it alone. But you can increase your cactus' chances for surviving the transplanting by taking the following steps:

  1. Choose a site where the cactus will receive about the same amount of sunlight as before, and orient the plant so that what was previously the sunniest side still is. That side will be the most resistant to sunburn.
  2. Dust wounds on the roots with sulfur to ward off infection.
  3. Place the plant no deeper in the ground than it was growing before. The roots of a cactus need to spread out close to the surface.
  4. Back-fill the hole with well-drained soil, not too rocky, then tamp it lightly with a wooden stick to eliminate air pockets without bruising the roots.
  5. Wait about two weeks before watering, to give the roots time to heal; then water sparingly during the first growing season (until cold weather).
You can increase your own chances for surviving the transplanting by wearing heavy gloves and being very careful.

One of the greatest problems for most transplants is water stress, but that's a condition cacti are superbly adapted to handle. A cactus' stored moisture buys it time while its roots regrow. Resist the urge to baby it by over-watering and it will probably do fine.


Other questions and answers in this chapter:
Why should I NOT be a cactus rustler?
When should I transplant cacti?
Do I need to do anything special to transplant saguaros?
Is it possible to grow cacti from cuttings?

The Book of Answers is available online from ASDM Press.


What's the concrete-like stuff buried in my garden?
It's a natural mineral deposit common in desert soils.

Soil scientists call it a "calcic horizon" (meaning, essentially, a calcium-rich soil layer) but almost everyone else knows it as caliche (kuh-LEE-chee). Caliche is the result of natural processes that deposit lime--calcium carbonate, CaCO3, the stuff of limestone--in arid soils. The lime can take many forms, from chalky powders to veins, lumps, coatings on rocks, and the thick, cement-hard layers that can be the bane of desert gardeners.

Heavy caliche causes three main problems for the roots of garden plants not adapted to it. First, naturally deep-rooted plants can't penetrate it. Second, it slows drainage, causing water to collect and drown roots. And third, salts left behind when the trapped water evaporates build up, poisoning the soil.

There are no magic chemicals you can add to the soil to dissolve caliche. But finding it in your garden doesn't mean you have to scrap your landscaping plans and install a patio instead.


Other questions and answers in this chapter:
The Caliche mystery: The answer was blowing in the wind
What can I do about caliche in my garden?
Do I need to remove caliche if I'm putting in desert plants?

The Book of Answers is available online from ASDM Press.


How can I keep wild animals from eating the plants in my garden?
You can avoid attracting the creatures or you can use physical barriers to keep them out.

Let's look at both these approaches in turn, keeping in mind that a combination of measures may work best in your particular situation.

How can I avoid attracting problem animals to my garden?

First, don't feed them! Obviously, deliberately feeding desert animals is offering them an open invitation to the premises, but so is feeding them inadvertently by putting out an uncovered garbage container or a dish of pet food. Many desert mammals are attracted by birdseed spilled on the ground from feeders, so choose a feeder that's spill proof, or, if you broadcast seed, put out only a handful at a time. These precautions will also help prevent spreading bird diseases.

Second, don't put in a pond or watering hole. This can be as much an "attractive nuisance" as food, and it, too, can spread disease.

Third, learn which plants will and won't be eaten. Ask other gardeners about their experiences and experiment on your own. Here's a start: strong-smelling and very spiny plants tend to be left alone. You'll probably have the best results if you avoid exotic plants and put in native species. They're likely to have evolved defenses against native herbivores.

Fourth, don't create a lush oasis by your landscaping. Dense vegetation will draw animals with the promise of food and moisture as well as shade and hiding places. The temptation to desert creatures is strongest during droughts, and you can minimize it at those times by not watering your desert plants. Be especially sure not to overwater--it may make your plants irresistibly tender and tasty.

Fifth, talk to your neighbors. Your own efforts will be of little avail if your garden becomes a stop on the javelina highway to an all-they-can eat restaurant next door.


Other questions and answers in this chapter:
What barriers work to exclude problem wildlife?

The Book of Answers is available online from ASDM Press.


How can I attract desert wildlife to my yard?
You can easily attract desert wildlife by providing food, water, and plant cover, but it's important not to overdo it.

Because the desert is dry, its plant and animal life is naturally sparse. If you encourage desert animals to gather in unnatural numbers the result can be problems both for them and for yourself. But if you exercise common sense and restraint, attracting a few desert creatures to our homes can be a harmless source of enjoyment.


Other questions and answers in this chapter:
What are some of the pitfalls I should avoid?
Butterfly Gardening?
What works?

The Book of Answers is available online from ASDM Press.


How can I attract hummingbirds?
The easiest way is to put out a feeder.

Hummingbirds are nectar-feeders, of course, so hummingbird feeders are simply artificial flowers filled with artificial nectar. Almost any commercially available hummingbird feeder will do, or you can improvise one yourself from a small container (say, a film can) painted red and hung from a wire.

To make the nectar, dissolve one part table sugar in four parts water, boil it for a minute or two to sterilize it, then let it cool. After filling the feeder, hang it in a shady place, out of the wind. You can store any leftover solution in your refrigerator.

Unfortunately, besides being hummingbird ambrosia, sugar water is an excellent medium for growing bacteria, fungi and other microorganisms. To prevent harm to the birds it's important to clean and refill your feeder at least once per week--twice that often in warm weather. Use a mild bleach solution (one part bleach to ten parts water) and rinse the feeder well afterward. A small bottle brush may help.


Other questions and answers in this chapter:
Should I add red food coloring to the sugar water in my feeder?
What if no hummingbirds come to my feeder?
What if other animals steal nectar from the feeder?
What times of year should I put out my feeder?
Is that all there is to it?

The Book of Answers is available online from ASDM Press.


What is trichomoniasis?
A nasty disease in birds.

Trichomoniasis in birds is caused by the protozoan Trichomonas gallinae. The disease has been known for centuries to people who rear feathered animals. Pigeon fanciers call it "canker;" falconers call it "frounce." (Trichomoniasis in humans is caused by a different microorganism. People can't catch trichomoniasis from birds, nor vice-versa.)

Trich usually infects a bird's mouth and throat, but it can spread widely through the body. It harms mostly young birds, but adults can be symptomless carriers. An infected bird may seem listless, emaciated, and unkempt--but it also may appear quite healthy. In severe cases it will usually have a cheesy material in its throat that can seriously interfere with swallowing and breathing.

Trich is most prevalent in pigeons and doves. Courting birds in this zoological family share the protozoan when they rub their beaks together--a behavior called "billing." They later infect their young when they feed them a regurgitated liquid called crop milk. Pigeons and doves may also spread trich by dropping seeds they're unable to swallow, and drinking (or trying to) at bird baths. The disease usually stays at low levels in pigeon and dove populations, but sometimes there are outbreaks (epizootics) during which many birds die.

Raptors like hawks and owls can be badly infected as nestlings when their parents feed them diseased prey. Much less is known about how frequently other desert birds are infected.


Other questions and answers in this chapter:
Are there other diseases in backyard desert birds?
How can I stop birds from flying into my window?
How can I feed birds without spreading disease?
How can I provide water for birds without spreading disease?
Given the possibility of spreading disease, wouldn't it be better not to give seed or water to wild birds?

The Book of Answers is available online from ASDM Press.


What should I do about an injured, sick, or orphaned animal in my yard?
First you must decide whether or not to get involved.

This isn't always easy. On the one hand, there's the reasonable view that nature should be allowed to take its course. On the other hand, a distressed animal in your yard may not be a "natural" situation--for example, it may have been injured by a neighborhood cat. And it's hard to let an animal suffer.

If you decide to take action, there are limits to what you should do yourself, to avoid harming both the animal and you. There are also legal restrictions to the "possession" of wildlife, which includes having wild animals in your care. Do only what's reasonable and if more is needed let a licensed wildlife rehabilitator take it from there.

Your community may have a central phone number for a wildlife rehabilitation organization (check the yellow pages under "wildlife"). If not, call a local nature center, zoo, or the nearest office of your state's fish and game department. They can refer you.


Other questions and answers in this chapter:
How much should I do myself?
Wildlife travel tips
How can I protect neighborhood wildlife?

The Book of Answers is available online from ASDM Press.


What's the best way to identify bark scorpions, black widows, and brown spiders?
Carefully.

Just kidding. But while these interesting arachnids aren't the fearsome creatures many people have been led to believe, it is true they can be dangerous under the right circumstances. It's an excellent idea to learn how to recognize them.

Bark scorpion (Centruroides exilicauda) Identification: A small scorpion, up to 1 and a half inches long, usually straw colored. The pincers and tail are noticeably more slender than in other Sonoran Desert scorpions, such as the stripe-tailed scorpion with which it's often confused.

Black widow spider (Latrodectus hesperus) Identification: An adult female is shiny black or dark brown and about an inch and a half across, including the legs. She has a globe-shaped abdomen about 1/2 inch across with a conspicuous red hourglass pattern on the underside. A juvenile female is smaller, with a cream-colored hourglass; she also has red, brown, and cream markings on top of her abdomen. Males are harmless and very small. Their bodies are less than 1/4 inch long and marked like young females, though they lack the globular abdomen.

Brown spiders (Loxosceles species) Identification: It's difficult. An adult brown spider is about an inch across counting the legs, smooth looking (not hairy or spiny), and tan to brown with unbanded legs and a darker upside-down violin-shaped marking on the front of the body. Unfortunately, the violin is hard to see, and there are many other brown-colored spiders, some with similar markings. Specialists count the eyes with a magnifier: brown spiders have six, while other similar spiders have eight. You may be able to do this, too--once the spider is safely in a jar!


Other questions and answers in this chapter:
Just how dangerous are bark scorpions, black widows, and brown spiders?

The Book of Answers is available online from ASDM Press.


How can I keep bark scorpions, black widows, and brown spiders out of my house?
Don't leave them any way to get in.

These are fascinating creatures, but it's perfectly reasonable not to want them as housemates! Start by installing good weather stripping around doors and windows. Then make an inspection tour of the outside of your house, sealing up every crack and crevice that could be an entryway. Openings needed for ventilation can be covered with screening.

All this will be of little avail if you inadvertently smuggle in the creatures yourself--for example, by failing to inspect a box before bringing it in from an outdoor storage shed. Special case: people sometimes carry home brown spiders (often mistakenly called "brown recluse" spiders) in attractive bits of cholla cactus skeleton they pick up in the desert.

What should I do about the scorpions and spiders I find indoors?
Few people would fault you for summarily dispatching a dangerous scorpion or spider with a fly swatter (or other convenient tool), but consider the alternatives. If you're not too afraid, you may be able carefully to scoop up the creature in a jar and relocate it outdoors. The animal may be out of place in your home, but it has significant ecological roles to play in the desert, both as predator and as prey.

If you're a parent, consider the lessons your actions give to your children. A fearful reaction in an adult teaches a child to be fearful, too; but making the effort to deal with a spider or scorpion without killing it teaches a respect for all living things. Besides, the opportunity to see the captive animal up close will help the child learn both how to recognize it and how interesting it is.

Of course, releasing your venomous visitor in your neighbor's yard would teach your child an unfortunate lesson of quite another kind!


Other questions and answers other chapters:
How can I keep dangerous scorpions and spiders out of my house?
What about the indoor spiders and scorpions I haven't found?
Would it help to eliminate scorpions and spiders in my yard?

Related questions and answers in other chapters:
How should I dentify bark scorpions, black widows, and brown spiders?
Just how dangerous are bark scorpions, black widows, and brown spiders?

The Book of Answers is available online from ASDM Press.


How can I tell if the bees in my yard are Africanized?
You usually can't. Africanized bees look almost exactly like other honey bees.

Africanized bees closely resemble the other honey bees in North America because they're just different races of the same species: Apis mellifera. Even experts have to make careful measurements to tell them apart. The most important--and interesting--differences are in their behavior.

Africanized or not, a few foraging honey bees are usually no cause for alarm. Unless you're allergic to bee stings, the only true danger is near an Africanized colony.


Other questions and answers in this chapter:
How can I keep Africanized bees from colonizing my house or yard?
What else can I do to stay safe from Africanized bees around my home?
Out of Africa: an ecological cliffhanger

The Book of Answers is available online from ASDM Press.


How dangerous are Africanized bees?
Africanized bees are more dangerous than other honey bees only when they're defending their nests.

Despite the unfortunate moniker "killer bees," bestowed by overheated news media, Africanized bees don't seek out and attack people out of sheer orneriness. In fact, the whole notion of these insects as exceptionally aggressive is misleading; better to think of them as highly defensive, and then only concerning their nests.

An Africanized bee taking a drink or gathering nectar and pollen away from its nest is as unlikely to bother you as any other honey bee is. Even if you manage to provoke it into stinging, say by stepping on it, its sting is no more dangerous. (Or no less dangerous: any honey bee sting is hazardous if you're allergic to it.

Swarms of Africanized bees looking for new places to colonize are usually innocuous, too. The bees tend to be so gorged with honey--provisions for the trip--that they'd have trouble stinging even if they were so inclined. (But why take chances? Keep your distance.)

The danger arises when you disturb well-established colonies. Africanized bees are much more sensitive than other honey bees to perceived threats to their nests. They're more likely to react, and they may react more quickly and in much larger numbers. Some Africanized bee colonies aren't very defensive, but others are. People and animals unable to escape severe defensive attacks have sometimes died as a result of multiple stings.

The bottom line? Statistically speaking, your chances of perishing in an Africanized bee attack are almost vanishingly small. On the other hand, if you happen to join the tiny minority of people who are attacked, you'll be in a potentially dangerous situation. It's worth knowing in advance how to respond.


Other questions and answers in this chapter:
What should I do if I'm attacked?
Now that Africanized bees are here, wouldn't it be best just to kill all honey bees?

The Book of Answers is available online from ASDM Press.


What kind of snake is in my yard?
We can tell you the most likely candidates.

There are any number of possibilities--including your neighbor's escaped pet boa constrictor!--but certain kinds of snakes show up in Sonoran Desert backyards much more frequently than others. Check these descriptions first. Rattlesnakes (Crotalus species)

Forget what you may have heard about rattlesnakes having triangular heads--some other desert snakes fit that description. And forget about diamond-shaped markings--not all rattlesnakes have them, and some other snakes do. Look (from a prudent distance) for the rattle.

If the snake has recently been born, the rattle will have just a single segment. If it's an older snake, some of the segments may have been lost. But the rattle will be there.

Consult a field guide if you'd like to identify the species --there are quite a few in the Sonoran Desert. For what to do about the rattlesnake in your yard.


Also discussed (and illustrated) in this chapter:
Gopher snake (Pituophis melanoleucus)
Common kingsnake (Lampropeltis getulus)
Whipsnakes (Masticophis species)
Western blind snake (Leptotyphlops humilis)

The Book of Answers is available online from ASDM Press.


How can I keep rattlesnakes out of my yard?
A low wall will keep out rattlesnakes (and most other snakes as well).

Snakes can't climb smooth vertical surfaces, so an untextured wall makes an excellent barrier. It needn't be more than a yard tall to keep out most snakes. Avoid building any corners that are concave toward the outside (a climbing snake might conceivably gain a bellyhold in the concavity), keep the outside of the wall free of vegetation, and make sure there's no "crawl space" under the gate.

A wall is probably a good idea if you're rearing small children in rattlesnake country. You don't need to enclose your whole yard; just create a "safe zone" where the children can play outdoors. You can inspect the area periodically to keep it free of other hazards, too.

Side benefits: the wall will also (1) help keep the kids from wandering off to parts unknown, (2) keep desert animals from drowning in your swimming pool, and (3) protect your prize plants from hungry rabbits and javelina.


Other questions and answers in this chapter:
Are there any alternatives?
What should I do if I find a rattlesnake in my yard?
What happens to relocated rattlesnakes?
A "Gila Monster" in every garage? - how to differentiate geckos from Gila monsters

The Book of Answers is available online from ASDM Press.


How can I stop woodpeckers from making holes in my house?
Persistence.

If you're setting out to solve a woodpecker problem, you're about to match wits with a very determined adversary. Woodpeckers are powerfully motivated to peck wood. In nature this characteristic behavior provides them with both food (insects) and nesting sites. Unfortunately for us, wood siding, beams, and posts (and sometimes stucco) encourage woodpeckers to do what comes naturally. Discouraging them often requires considerable ingenuity.

Here are some of the many remedies others have tried. Sometimes they work.

No two houses or birds are alike. It will probably take some experimentation to find the tactic (or combination of tactics) that works at your home with your woodpecker. The sooner you get started the better. A bird that's made a habit of drilling into your house is harder to deal with than one that's taking its first few tentative pecks.

Be creative! If you come up with something original and effective, call the Desert Museum so the staff can share it with other beleaguered homeowners. You are not alone.


Other questions and answers in this chapter:
Why does the woodpecker pound on my metal evaporative cooler?

The Book of Answers is available online from ASDM Press.


Why do packrats keep making houses in my car's engine compartment?
Because it's such an inviting place to live.

Packrats in the Sonoran Desert often build their houses under trees and prickly pears, but they also frequently make dens in protected rock niches and caves. To a packrat your engine compartment is just another cave. Because the animal's ancestors evolved in the absence of automobiles, it has no idea that this particular cave may someday make a loud noise and move.

Unfortunately, the packrat doesn't just drag in sticks and cholla joints; it also chews on the wires and hoses. This isn't a calculated effort to immobilize your vehicle--though it certainly can have this effect! The packrat is probably just rearranging its living quarters, or satisfying a rodent's primal urge to gnaw.

Packrats and paleoecologists
Packrats (Neotoma species), called "woodrats" in most field guides, are attractive rodents, about the size of house rats, but with fur-covered tails and light-colored feet. They're nocturnal and secretive, so you're much more likely to see their debris-pile homes than the builders themselves. These messy-looking dwellings are actually elaborate structures, with multiple entrances and passageways, and they shield their occupants well from both predators and the weather.

In dry caves packrat refuse piles ("middens"), cemented together by evaporated urine, can last tens of thousands of years. Paleoecologists identify species of plants from fragments and seeds in these deposits, age them by radiocarbon dating, and reconstruct how plant communities have changed over time. Thanks to packrats we know that during the last Ice Age, which ended about 11,000 years ago, much of what is now the desert Southwest was home to pinyon pines, junipers, and oaks! Desert plants began to move in from warmer refuges as the climate heated up, and today's Sonoran Desert communities took shape only about four or five thousand years ago.

It had happened many times before. In the last two million years the desert has retreated fifteen to twenty times during as many Ice Ages, and re-advanced in the warm intervals between. We seem to live in one of the warm "interglacials" now. The oaks may return--and more than once!


Other questions and answers in this chapter:
What can I do about it?
What about the packrat in my attic?
Aren't insects that live with the packrats also a problem?
Should I be concerned about hantavirus?
What's the connection between paleoecologists and packrats?

The Book of Answers is available online from ASDM Press.


How can I protect my pets from coyotes and bobcats?
By keeping your pets out of harm's way, and not attracting these two predators to your property.

Coyotes are anything but finicky eaters. In natural desert habitats they feast on everything from crickets and cactus fruits to quail, cottontails, carrion, and deer. It's no stretch for them to add domestic cats and small dogs to their nutritional repertoire. Bobcats, on the other hand, have more refined tastes: they eat mostly rodents, rabbits, and jackrabbits (less often birds and lizards). They're less inclined to make a meal of your pet--but it happens!

Fortunately, there are things you can do to keep your dog or cat off the menu.

Neither coyotes nor bobcats confine their activities to the open desert and the suburbs. Coyotes are quite common in urban habitats, and even bobcats show up surprisingly often in cities, especially where cottontails graze on watered lawns.
Other questions and answers in this chapter:
Are these animals a threat to me or my children?
Predatory pets?

The Book of Answers is available online from ASDM Press.


What might I bring on a hike to help me enjoy the desert?
As little as possible.

Part of the fun of venturing into any wild place is the feeling of being unencumbered, so the trick is never to take too much. Here are a few items that are especially likely to add to your enjoyment without weighing you down.

Many people assemble a simple desert hiking kit in a day bag and keep it always ready to go. You'll want to include a few comfort and safety items, too.
Other questions and answers in this chapter:
What else should I put in my pack?

The Book of Answers is available online from ASDM Press.


What precautions should I take when hiking in the desert?
Safe desert hiking is mostly a matter of common sense, carrying enough water, and dressing appropriately.

Except for the climate, hiking in the desert isn't that different from hiking anywhere else, and most of the same rules apply. Here are a few tips for playing it safe in cactusland.


Other questions and answers in this chapter:
Flash!...Boom! What should I do in a lightning storm? How much water should I bring?
What clothing is best for desert hiking?
No Sweat?

The Book of Answers is available online from ASDM Press.


If I run out of water in the desert can I get some from a barrel cactus?
Perhaps, but it would be truly a desperation measure.

Yes, some Sonoran Desert Indians have extracted moisture from barrel cacti, and yes, others have occasionally done it, too, but there are compelling reasons not to try to replicate this legendary feat yourself.

  1. It's hard to get inside a barrel cactus. Many desert animals would be pleased to plunder that hidden moisture hoard, so it's no accident a barrel cactus is extraordinarily well fortified. Its largest spines are stout, curved, and easily hook your flesh, and its skin is extremely tough.
  2. There's no tempting pool of clear water inside a barrel cactus, only plant tissue resembling a damp, slimy sponge. Moisture must be laboriously pounded, squeezed, or chewed out of this stuff, and by some accounts it doesn't taste very good.
  3. At hot, dry times of year a barrel cactus may have limited moisture reserves, so you may not gain much for all your efforts. You might even sweat away as much moisture trying to break into the plant as you would gain if you succeeded.
  4. Only one species of barrel cactus is known to yield potable moisture: the fishhook barrel (Ferocactus wislizeni). Many other cacti (including other barrels) are toxic, so if you couldn't recognize the right plant with certainty, you'd be in danger of poisoning yourself. The toxins probably wouldn't kill you, but the likely effects--vomiting and diarrhea--are among the worst possible for anyone already suffering from dehydration.
  5. All cacti are protected by law in both Arizona and California.

Other questions and answers in this chapter:
Are there better ways to get water in the desert?
Teetotalers - How do desert mammals deal with a lack of water?

The Book of Answers is available online from ASDM Press.


Are cactus spines poisonous?
No, this is just a myth.

Getting stuck by cactus spines isn't one of life's more pleasant experiences, but when it happens to you--and if you spend time outdoors in the desert, sooner or later, inevitably, it will--at least being poisoned is something you won't need to worry about.

Still, try to remove spines right away, and not just because they hurt. Left in the skin they're more likely to cause local inflammation as your immune system reacts both to the spines themselves and to any bacteria residing on their surface.

With all deep puncture wounds tetanus infection is a remote but real possibility. Cacti are one more reason for desert dwellers to keep their booster shots up to date.

What good are cactus spines?
Cactus spines didn't evolve to punish clumsy hikers. Their chief function, as one might expect, is to protect cacti from hungry animals. It doesn't always work. Javelina devour entire prickly pear pads, spines and all, and thirsty jackrabbits and cottontails nibble carefully between the areoles. Spines may offer little impediment to cactus-consuming bugs and beetles, though flying insects occasionally blunder into them, impaling themselves helplessly on the tips.

Spines of some of the more densely-cloaked cacti collectively shade the plants from overheating and sunburn, and the thick mat of spines at the growing tip of a saguaro or barrel cactus provides insulation against freezing on clear winter nights. A cholla segment that affixes itself by means of its spines to a passing deer or hiker serves a reproductive purpose: it may eventually sprout roots after being disengaged some distance away.

Animals sometimes turn cactus spines to their own advantage. Packrats pile the fiercely spined joints of chollas around their dens, discouraging predators. Certain birds seem to nest in spiny chollas for similar reasons, but must protect their own nestlings from the hazard. Cactus wren nestlings are safe inside covered nests, while curve-billed thrasher parents systematically break off the tips of spines near their nest cups. Mummified snakes are sometimes found entangled in cholla spines--the aftermath of failed nest raids.

Even human beings have found uses for cactus spines. Native people have fashioned sewing needles from them, and used curved barrel cactus spines as fish hooks. A stout prickly pear spine (with the tip snapped off) makes a fine toothpick, and cactus spines were once sold as record playing needles for wind-up Victrolas!

What's the best way to remove cactus spines?
An elaborate folk technology has evolved to deal with this problem in all its variations. Incidentally, there are wild cacti in all the contiguous states except Maine, New Hampshire, and Vermont, so desert dwellers don't enjoy a monopoly in these mild forms of torture.


Other questions and answers in this chapter:
Are cactus spines poisonous?
What's the best way to remove cactus spines?

Related questions and answers in other chapters
How can I tell cacti from other spiny desert plants?
If I run out of water in the desert can I get some form a barrel cactus?


Other questions and answers in this chapter:
What's the best way to remove cactus spines?
What good are cactus spines?
Do jumping chollas jump?

The Book of Answers is available online from ASDM Press.


Why don't I see very many animals when I hike in the desert?
Perhaps because you and the animals are on different schedules.

Many of us desert humans follow a nine-to-five routine, a way of life that would be utterly impractical if it weren't for air conditioners and evaporative coolers. Other desert animals aren't constrained by our peculiar customs; they follow the dictates of the climate. If we want to meet them in their natural habitats we need to set our schedules by their biological clocks.

Most desert birds have two main activity periods: a major peak in early morning and a minor one in the evening. Birds are taking it easy--and therefore harder to find--precisely when people are habitually most active. To see the most desert birds you need to be outdoors and looking when the sun comes up. Better yet, catch the "dawn chorus" of awakening birds as the sky lightens before sunrise. It's well worth the effort.

Many desert mammals beat the heat by being nocturnal (night active) or crepuscular (active in the twilight at either end of the day). Some, like javelina, adjust their schedules to the seasons, becoming more diurnal (day active) when the weather is cool. Just as with birds, evening and early morning are almost always good times to see desert mammals, but mid-day almost never is.

For an especially rewarding desert wildlife experience, try a walk after dark on a warm summer night. See other parts of this chapter.


Other questions and answers in this chapter:
Are some desert places better than others for seeing wildlife?
Is there anything else I can do to see more desert wildlife?
What about desert night life?

The Book of Answers is available online from ASDM Press.


How dangerous are Sonoran Desert toads?
Sonoran Desert toads pose no serious danger to people who are reasonably careful.

Sonoran Desert toads (Bufo alvarius), sometimes called Colorado River toads, are hard to miss. They're the bullfrogs of the toad world, growing up to 7 1/2 inches long--much larger than any other toads in Arizona or California. Adults are brownish or olive, but younger individuals tend to be lighter colored with reddish blotches. Except for the tiniest toadlets, they all have distinctive white warts at the corners of the mouth.

Slow-moving and lacking in physical defenses, all toads depend to some degree on chemical weaponry for protection against predators. Poisons are produced by glands all over a toad's skin, but especially in two raised paratoid glands behind the eyes. The Sonoran Desert toad's secretions are especially toxic: they can disrupt nerve and muscle function in a mammal naive enough to get one in its mouth.

Unless you do something careless or foolish (see other parts of this chapter) a Sonoran Desert toad has no method--or reason--to get its toxins into you. If you pick one up be sure not to touch your eyes or nose or to handle food until you've washed your hands. Other desert frogs and toads are less potent, but you should wash after touching them, too.

Incidentally, the water in your swimming pool will still be quite safe after a Sonoran Desert toad has been in it, but for the sake of the toads--and other desert animals in danger of drowning--you might consider a low wall to keep them out. Such a wall can have other benefits, too.


Other questions and answers in this chapter:
Should children be allowed to handle Sonoran Desert toads?
How can I protect my dog from Sonoran Desert toads?
Holy Smoke! - Are people more intelligent than their pets?

The Book of Answers is available online from ASDM Press.


If I find a desert tortoise while I'm hiking, would it be all right to take it home as a pet?
No, you shouldn't take any animal from the wild as a pet, especially one as uncommon as a desert tortoise.

Besides, it would be illegal. Desert tortoises are protected by state laws everywhere they naturally occur in the United States--and in some areas by federal law as well. In fact, not only shouldn't you take a wild tortoise home, you shouldn't even pick one up. Here's why.

Unlike us, a desert tortoise can reabsorb moisture from its bladder; in effect, it carries a built-in canteen. If you pick up a wild tortoise, the frightened reptile is likely to dump its water supply--a minor nuisance for you, but a major problem for the tortoise, which in a severe drought could die before the next rainstorm allows it to refill!


Other questions and answers in this chapter:
If it's illegal to collect wild tortoises, how can people have them as pets?
Where should I release a tortoise I can no longer care for?
Are tortoises endangered?
A case of the sniffles?

The Book of Answers is available online from ASDM Press.
Links to more Desert Tortoise information
Back to the top


How can I avoid dangerous encounters with rattlesnakes and Gila monsters when I'm hiking?
Always pay attention to where you're going, and use a flashlight at night.

Rattlesnakes will strike at you only if they're molested or startled, so if you don't plan to bother them your task is simply to avoid making a sudden and unexpected appearance in their immediate vicinity. As for Gila monsters, you practically have to put your hand or foot on them to get bitten.

Here's some specific advice.

Be cautious, but don't worry. Rattlers and Gila monsters don't lie in wait for hapless humans. Their first line of defense is simply to be inconspicuous: hikers often walk right past them without knowing it. (But perhaps that isn't reassuring!) Still, if you hike in the desert often, sooner or later you'll have the pleasure of meeting a rattlesnake or a Gila monster along the trail.
Other questions and answers in this chapter:
What should I do if I come across a rattlesnake or Gila monster?
Don't Tread on Me - Can you tell me more about rattlesnakes?
What about tarantulas?

The Book of Answers is available online from ASDM Press.


Are there other venomous reptiles in the Sonoran Desert besides rattlesnakes and Gila monsters?
The western coral snake is the only other reptile in the American Southwest with a venom dangerous to people.

The western coral snake (Micruroides euryxanthus) is a small, shiny snake with red, yellow, and black bands around its body. Its venom is highly toxic, but its tiny mouth makes it difficult for it to bite a creature as large as you, and it's extremely unlikely even to try unless it's handled. You may hike in the desert for decades and never see a coral snake. An encounter with one of these beautiful and secretive creatures is an occasion to savor, not to fear.

The western coral snake's bright markings are warning colors (aposematic colors)--they serve notice that the snake is dangerous. Interestingly, there are several harmless desert snakes with colors similar to the coral snake's. Their markings may fool potential predators into thinking these snakes are dangerous, too. The evolution of living things that look (or sound or smell) like others for deceptive purposes is called mimicry, and it's happened many times in animals and plants.


Other questions and answers in this chapter:
How can I tell the western coral snake from its mimics?
Which snakes are "Short in the Tooth"?

The Book of Answers is available online from ASDM Press.


What is valley fever?
Valley fever is a usually mild (but sometimes serious) disease caused by a fungus that lives in desert soils.

Valley fever, technically called coccidioidomycosis, or cocci (KOK-see) for short, is caused by the soil fungus Coccidioides immitis (sidebar). Microscopic spores produced by the fungus are released into the air when the ground is disturbed, and can infect people who inhale them. Some wild and domestic animals can get cocci, too. Cocci isn't contagious: you can't catch it from an infected person or animal.

Cocci occurs in the Sonoran, Mohave, and Chihuahuan Deserts of the United States and Mexico, as well as in the drier parts of Central and South America. It's not completely confined to desert areas; people living in the semiarid areas bordering deserts can be infected as well. The disease is especially common in the San Joaquin Valley of California--that's how it got the name "valley fever"--and in southern Arizona.


Other questions and answers in this chapter:
What are the symptoms?
What should I do if I suspect I have valley fever?
How can I avoid getting valley fever?
Can I catch cocci more than once?

The Book of Answers is available online from ASDM Press.


What precautions should I take when driving in the desert?
Take care of both vehicle and driver, and use common sense.

Highway travel in the Southwest has come a long way since the days when trembling stagecoach passengers relinquished their watches to banditos in black hats--but it still pays to be careful!


Other questions and answers in this chapter:
Any special advice for back-road travel?
How can I tell whether or not it's safe to drive across a flooded wash?
What should I do if I'm caught in a blinding dust storm?

The Book of Answers is available online from ASDM Press.


How can I minimize my impact on the desert?
You can begin by taking only memories and leaving only footprints.

This often-repeated saying has special meaning in a desert, where plant and animal life is sparse and the land is slow to heal.

"Take only memories" means resisting the natural human impulse to collect beautiful objects. An unpicked wildflower feeds pollinators now and--thanks to the seeds it will produce--in future years as well. Left alone, an animal bone will be gnawed by desert rodents to recover its calcium. Feathers and cactus skeletons, too, will eventually be broken down and recycled into living plants and animals.

Even interesting stones should be left for others of your own species to enjoy. And of course prehistoric and historic artifacts should stay as you find them. If you'd like a reminder of your discoveries, consider taking photographs, making sketches, or keeping a journal.

In the desert "leave only footprints" should probably be amended with "and as few of those as possible!" Stay on trails when you're hiking, or if you must go off-trail, try to put your feet where they're least likely to do harm: on stones where they'll leave no marks, or in sandy washes where they'll more quickly be erased. Try to avoid stepping on plants or the living crusts called cryptobiotic soils.

Your automobile leaves even larger footprints than you do, so it's important to keep your tires on the road. Unfortunately, some off-road vehicle enthusiasts consider the desert their playground. Needless to say, this can be a terribly destructive form of recreation.


Other questions and answers in this chapter:
Are there other things I can do to keep from disturbing desert wildlife?
Any special recommendations for campers?
Anything else?

Elsewhere in the Book of Answers:
How did the Indians live in the Sonoran Desert?
Where are the O'odham today?

The Book of Answers is available online from ASDM Press.

What can I do to explore the desert?
Visit many places, but get to know at least one of them well.

We're fortunate that so many interesting Sonoran Desert habitats are in public ownership. These places belong to us, and it's worth seeing as many of them as we can. Don't limit yourself to National Parks and Monuments; visit National Wildlife Refuges, National Forests, and National Recreation Areas, as well as state and local parks. But take your time--you don't have to see them all in one year! You'll find it much more enjoyable to spend several days exploring each one than to rush from one to the next.

Exploring far and wide is a wonderful part of getting to know the desert, but many people find their greatest satisfaction in becoming intimate with a single place. Your favorite location needn't be a large area or far away--perhaps just an interesting trail a few minutes from home, or even a desert backyard. Visit it again and again. Look for the blooming cactus, the black beetle, and the bobcat's track. Watch the winter storm and the rising moon. When the rocks start to seem like old friends, your best explorations may be just beginning.


Other questions and answers in this chapter:
What can I do to help me learn about new places I visit?
What can I do to help me remember what I've experienced and learned?
Any other advice?

Submit your own Sonoran Desert Questions
We will do our best to either answer your question or refer you to others who are better able to do so. Comments on the information provided on this website are also welcome. e-mail: info@desertmuseum.org