Mojave Desert


Ode to the Creosote Bush

A desert tortoise pauses under the shade of a creosote bush.

A desert tortoise pauses under the shade of a creosote bush.

The southwest desert is thought of as a barren landscape by many, yet you may be surprised to learn that the Mojave Desert is diverse with plants and animals, all conditioned to survive the extremes of this environment. The desert tortoise is a keystone species of this desert and well adapted to an arid climate. Desert tortoise burrows offer protection for other desert species from predators and harsh weather conditions, and they disperse seeds from the native plants that they eat, repopulating the desert ecosystem with them!

Although it’s unlikely you’ll have a random encounter with a desert tortoise in the wild, it is common to see Larrea tridentata, commonly known as the creosote bush. This is a dominant shrub of the desert southwest and where desert tortoises tend to build their burrows due to the soil stability resulting from the creosote’s root system.

A creosote bush provides shelter for ground dwellers.

A creosote bush provides shelter for ground dwellers.

The creosote bush is also the most drought-tolerant of the desert southwest, with a waxy coating on its leaves that prevents water loss. During times of extreme drought, old branches and roots of creosote bush die back, returning only when it rains. Although, this shrub isn’t a primary food source, is does provide shelter to many animals.

As a desert dweller, rain is rarely in the forecast for me, but when it is, my senses are stimulated by the refreshing odor in the air, and I have often wondered, what causes the rain to smell? Well, the unique camphor-like odor in the air is from the creosote bush! When it rains, this waxy layer on the leaves volatilizes, producing the smell of rain.

I’ve called the desert southwest my home for a majority of my life, yet I continue to learn and appreciate the wonder of the desert around me every day!

Pamela Flores is a research associate at the San Diego Zoo Desert Tortoise Conservation Center in Las Vegas, Nevada. Read her previous post, Students Help Desert Tortoises.


Rain in the Mojave Desert

A desert tortoise prepares to snack on a desert mallow.

When most people think of the desert, they don’t think much about rain. Well, on August 22, the Mojave Desert experienced record-breaking rainfall, with some areas receiving well over 2.5 inches (6 centimeters) of rain within a 24-hour period, which caused major damage to the area. Most damage was due to washed-out roads and to low-lying property. But altogether, the desert had a much-needed drink for such a hot and dry summer.

Desert plantains have sprouted after record rainfall in the Mojave.

The aftermath of so much rain caused an explosion of plant life to appear throughout the desert. Some plants had not been seen in certain areas for many years. Plants such as the desert plantain Plantago ovate, desert mallow Spaerlcea ambigua, and golden bush from the genus Ericameria, just to name a few, started growing all over the desert. These plants are some of the desert tortoises’ favorite foods, which will help them have a full stomach before they go down for hibernation in the winter.

Daniel Essary is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center. Read his previous post, Rabbits, Rodents, and Tortoises.


Tortoises and Their Amazing Feats

A translocated desert tortoise carries the radio transmitter and GPS unit we use to monitor its movements.

My life as a field biologist finally seems to have slowed down as of late. With the cold weather settling in here in the Mojave Desert and the desert tortoises all hiding deep in their burrows, I finally have a chance to reflect back on my first year here working as a researcher for the San Diego Zoo’s Desert Tortoise Conservation Center in Las Vegas, Nevada. I’ve spent the past 12 years of my life studying amphibians and reptiles both around the country and throughout the world. But I must admit, chasing turtles and lizards in tropical rain forests or frogs on tiny islands in the South Pacific did not quite prepare me for working with these iconic desert creatures.

At first I thought, “Desert tortoises: how hard can it be?” After years of searching for silent frogs the size of an Oreo cookie in a dark forest at night, finding a tortoise the size of a dinner plate in a wide-open desert should be a piece of cake, right? And really, how fast can a tortoise possibly move? We’ve all grown up with the story of the tortoise and the hare…and yet even as a trained herpetologist, I was about to be amazed.

Jennifer radio-tracks translocated desert tortoises in southern Nevada.

Desert tortoises have adapted remarkably well to their arid environment. Despite, and perhaps because of, their size, they blend in with all the other rocks and rubble on the desert floor. Even with a radio transmitter glued to their shells, I’ve walked by more than a few, only to turn around to see their little faces peering at me from under their shell, hoping that I would keep on walking and mistake them for a another rock in the sunlight.

And as far as running? Well, tortoises may not be as fast as a hare, but they can definitely move. Currently, as human development takes over more and more of our pristine desert habitat, animals like the desert tortoise are often translocated or moved out of harm’s way. Unfortunately though, when you move a tortoise and drop it Bear Grylls-style into unknown territory (well, maybe not quite Man Vs. Wild style, as we do place our animals carefully in new sites and don’t make them jump out of airplanes and boats), the tortoise runs. Maybe not as fast as a cheetah or a Boston marathoner, but in true tortoise fashion they get their little legs going and race off.

This has been one of the focuses of my research: to figure out what affects an animal’s drive to move and how they behave following a translocation. After all, when we move animals out of harm’s way and to a safe place, we don’t want them to run home or leave the safety of our release site after translocation. Besides that, running takes an awful lot of energy, and if you are a creature adapted to the unforgiving desert environment, you want to conserve as much energy and food resources as possible.

Hillary, one of our translocated tortoises, comes down from the mountain (behind her) that took 10 days for her to climb.

Over this past year, I have spent countless hours trekking through the desert chasing after our tortoises to see where they went. One of them, Hillary (named after Sir Edmund of Mt. Everest fame), ran off right after the translocation and, living up to her name, took 10 days to climb all the way to the top of a mountain, stopping only at the base of a sheer cliff. After 10 days of climbing the mountain after her, to my great relief Hillary came back down and returned to the desert floor, settling in a wash only a few hundred yards/meters away from where we released her. Kenya, another of our amazing desert tortoises, spent the first few weeks after the translocation making daily movements of nearly a half mile (kilometer) or more. This is no small feat for a tortoise! With their tiny little legs, this would be like us walking over 10 miles (15 kilometers) a day!

Besides these amazing feats, surviving in the desert in a completely unknown area following a translocation is an accomplishment in itself. Most of our tortoises have stood up to the challenge and have made it through their first eight months at the new translocation site. While my team and I returned to our trucks at the end of each day, often sunburned and parched after hours of radio tracking, our desert tortoises have soldiered on. With hardly any rain and temperatures that soar to over 110 degrees Fahrenheit (43.33 degrees Celsius), these tough little critters survive and thrive in an environment that would put most of the staunchest humans to shame. It’s not an easy task, but I hope the knowledge we gain from our research will help to make future translocations at least a little bit easier on these resilient critters. It’s a tough life out there in the desert, and they deserve all the help they can get.

Jennifer Germano is a postdoctoral researcher at the San Diego Zoo Desert Tortoise Conservation Center.


Rabbits, Rodents, and Tortoises

A new perimeter fence for the DTCC.

Hello again to all desert tortoise enthusiasts! It’s about that time of year for desert tortoises to begin their winter hibernation. For anyone who is new to the desert tortoise Gopherus aggaszzi, this is the time of the year when temperatures start to drop and food becomes scarce. With this seasonal change, desert tortoises begin to slow their metabolism and physical performance and search for a dark, comfortable burrow to “sleep in” through the winter until temperatures warm and food becomes more available.

Finding a secure, empty burrow in the Mojave Desert can be more difficult than just finding a hole in the ground. Desert tortoises search or create their own shelters: they may dig burrows, take another animal’s burrow, or find a small cave that protects them from the cool winters of the Mojave Desert. There are many other animals here that also are looking to hibernate or find shelter from the cold; they may cohabit a burrow with the desert tortoise through the winter season. Animals that have been known to share burrows with desert tortoises are black-tailed jackrabbits and desert cottontail rabbits as well as predators like kit foxes, coyotes, and even badgers.

Recently at the San Diego Zoo Desert Tortoise Conservation Center (DTCC), a new, reinforced fence was built to help control the movement of predacious animals onto the property. Prior to the new fence, coyotes, kit foxes, and even badgers would dig below the fence line to enter the property. This situation became a problem due to attacks on the desert tortoises and the destruction of the grounds at the DTCC. Once the new fence was built, there were no more issues with predacious animals entering, killing, or harming the tortoises.

Unfortunately, the DTCC now has a much larger problem with the local fauna. Since larger, predacious animals are not entering the property, nothing is controlling the population of smaller mammals such as rabbits and antelope ground squirrels. These animals do not directly harm the tortoises at the DTCC but harm them indirectly by scavenging the tortoises’ chow, grasses, and water we put out for the tortoises. It only shows that changing an animal’s ecosystem is not always the best answer to conserving that ecosystem.

Daniel Essary is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center. Read his previous post, Desert Tortoise: Hot, Hot, Hot.


Saving Tortoises, One Urolith at a Time

An x ray shows an adult desert tortoise with a large urolith on the left.

The tortoises have begun their fall slow-down and are preparing for their winter brumation (reptilian hibernation) here at the San Diego Zoo Desert Tortoise Conservation Center in Las Vegas. This means that the priorities in the medical center will shift a bit. We will have a few tortoises staying awake for the winter because they are either too sick or injured to brumate. However, we will also have a number of residents staying in the medical center waiting to have surgery at the state-of-the-art Harter Veterinary Medical Center, located at the San Diego Zoo Safari Park. All of these tortoises have dangerous uroliths that have developed in their bladder (uroliths are analogous to kidney and bladder stones in people).

A large stone removed from an adult tortoise carcass

Uroliths develop for various reasons, the most common being improper nutrition or prolonged dehydration. One of the adaptations that tortoises have that allows them to thrive in the arid desert environment is the ability to store large amounts of water in their bladder and to reabsorb it as the body needs it. As they reabsorb the water in their bladder, the solid particles in the bladder become more concentrated and can stick together. As time goes on more solids are deposited in the bladder and combine with those already present, forming a stone. Therefore, stones are more likely to form if a tortoise goes long periods of time without consuming fresh water to flush and replace the stored water.

Small stones that form can pass out of the bladder when the animal eliminates. However, once the stone becomes a certain size, it can be too big to pass and remains in the bladder where it can continue to get larger. If the stone is there long enough, it can adhere to the walls of the bladder, making it very difficult to surgically remove it without damaging the bladder. Eventually the stone can get large enough to take up most of the bladder space, thereby taking up very important water storage space. This compounds the problem by increasing dehydration in the tortoise. Eventually the stone can block the urethra, preventing the tortoise from eliminating at all and causing a build up of toxins in the tortoise. The long-term presence of uroliths can result in a prolonged, painful death.

A desert tortoise recovers from surgery to remove a stone.

We palpate every tortoise during its health assessment to see if we can feel a coelomic mass. Sand or gravel in the bowels or eggs can feel similar to uroliths during palpation, so we x-ray every tortoise in which we feel a mass to determine what the mass is. Once we have x-ray confirmation that it’s a urolith, we send the tortoise to the hospital, where veterinarian Nadine Lamberski has developed a less invasive technique to remove the stone. Traditionally, the most common stone removal technique used by veterinarians was to remove part of the plastron (the bottom part of the shell) to get to the stone. This procedure is very invasive and can take a very long time to heal since the bone of the plastron has to be removed. The veterinarians at the Safari Park use a technique in which they make an incision in the skin of the prefemoral area (just in front of the hindlimb) so they can access the stone and break it down and remove it without having to remove part of the shell. This surgery can take up to 6 hours to perform, but the recovery time for the tortoise is much quicker for this procedure. I am very excited to say that the veterinarians have performed a number of these surgeries successfully, and our tortoises have been able to return to us with a much better future in store for them.

We have a number of tortoises ready for surgery this winter. Once they recover, they will be able to be released to the wild Mojave Desert in the healthiest condition possible next year to live out their long lives in a natural environment.

Rachel Foster is a research associate at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Desert Tortoise Hibernation: Not for All.


Desert Tortoise: Rainy Day Translocation

Pamela carefully places a desert tortoise into the Mojave Desert.

It’s 5 a.m. and a busy morning for the staff at the San Diego Zoo Desert Tortoise Conservation Center (DTCC) in Las Vegas, Nevada. We are anxious for the big day ahead, because it’s time for our fall translocation of desert tortoises back to the Mojave Desert, where they will live freely in their native habitat.

This day begins unlike most days in the Las Vegas Valley; the air is cool, and dark, ominous clouds linger over the city. As our mini-caravan of 3 vehicles, 10 people, and 72 tortoises head south on the I-15 toward the U.S. Fish & Wildlife-approved release site, we enjoy a torrential downpour of rain! The clouds are so dark, and the wind and rain are so strong, that it’s difficult to see the vehicles ahead of us. It has been a long, hot, dry summer, and we are thrilled to see the rain, but we think that perhaps this may not be the best day for hiking and releasing tortoises. But only moments later the storm passes, the skies are clear, and it’s another beautiful morning in the Mojave Desert.

The DTCC team provides fluids to a tortoise about to be released.

When we arrive at the release site, DTCC staff members administer fluids to the tortoises, ensuring they are well hydrated for their new journey. We take our time, because we want to give every tortoise the best chance of survival, and providing them with these extra fluids may carry them through a period of unexpected drought in the months to come.

Once the final tortoise is released, we take a deep breath, admire the beautiful landscape, and head back to civilization. But on the way, we discovered a wild tortoise crossing a paved road. Normally, we would watch the tortoise from a distance, ensuring its safe arrival to the other side of the road, but not this time. In the distance we see a fast-moving vehicle heading straight toward us, so we immediately jump out of our truck, and Paul, one of our seasonal research assistants, quickly but carefully moves the tortoise off the road to safety several hundred yards into the desert. What a great way to end the day; we saved a wild tortoise from possible injury or death.

The desert tortoise moments before its rescue from an oncoming vehicle.

Every translocation we conduct takes place at a release site here in southern Nevada that is approved by our partners at the U.S. Fish and Wildlife Service (USFWS), the Nevada Department of Wildlife, and the Bureau of Land Management. The San Diego Zoo is the only organization approved by USFWS to return desert tortoises to the desert; that’s because we put tortoises through a full battery of medical and behavioral tests for at least a year to ensure they are completely healthy before they leave the facility.

Pamela Flores is a research associate at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Spring Desert Tortoise Translocation.


Tortoise Tales: Tracking Desert Tortoises

Lindsey poses with a desert tortoise in the Mojave Desert.

We translocated a group of desert tortoises from the San Diego Zoo’s Desert Tortoise Conservation Center (DTCC) into the wild Mojave Desert and followed them to study their movements post-release (see Spring Desert Tortoise Translocation).  My days started at 5 a.m. at the release site out in the desert. There are six separate sites that our tortoises reside in, and it was my job to locate every one of these tortoises every week. While working on this project, I saw some interesting things in the desert!

Immediately after translocation, the tortoises began to move around looking for their new homes. A small group took an especially long journey to the corner of the site, all at least a kilometer (0.6 miles) away from each other and from any other study tortoise. One resident tortoise living in this area joined our study, so we were able compare her movements as a normal wild tortoise to those of the tortoises we translocated. I nicknamed her Mrs. Rogers, because she was the only resident tortoise in a whole neighborhood of translocated tortoise friends. This site from then on was known as Mrs. Rogers’ neighborhood. In the future, we hope a male tortoise will take on the role of Mr. Rogers to help increase the population!

Lindsey uses tracking equipment to help find translocated desert tortoises.

I ran into a bit of luck one day while tracking a resident tortoise in another area. When I finally located her, I saw that she was flipped on her back, unable to right herself.  Was this due to a scuffle with another tortoise or a run-in with a predator? Because of the unique anatomy of a tortoise, death can occur if a tortoise remains on its back for an extended period of time because it is vulnerable to dehydrating and overheating if unable to seek shelter during the hottest parts of the day. I immediately righted the tortoise, wondering if I was too late. Fortunately, she walked away, seemingly unharmed.  A month after that incident, that resident tortoise is still doing great!

Sometimes, tracking tortoises can be a tricky job. Change in elevation, tortoise movement, and other obstacles make it difficult to get a good signal on our equipment. Sometimes, though, the tortoises make it easy. As I drove down the desert road, I was listening for one tortoise when I saw another study tortoise walking across my path. At first I was pretty excited, because this was one less animal I had to search for, but then I noticed he was missing his GPS unit, which we attached to him before he was released. The GPS units are only programmed to emit a signal for a certain period of time, and at that moment I only had about five minutes to locate it before the signal stopped. I quickly entered the GPS frequency and began searching for the unit. I finally found the missing unit in the mouth of a nearby burrow only a moment after the beeping stopped. The unit was recharged and reprogrammed and put back on the tortoise shortly after.

One afternoon I was tracking a group of tortoises in a wash, and I found something none of us had yet come across. There were several broken eggs in the dirt surrounding the caliche cave where one of my tortoises was living. Unfortunately, a predator attacked this clutch before hatching, but under good environmental conditions a tortoise may produce two clutches per year, so maybe next time we will see some hatchlings!

This badger was found in a desert tortoise burrow.

It is not unusual to come across a tortoise digging a soil burrow while tracking our study animals. One morning I was approaching a burrow in a wash, and I saw dirt flying out of it. As I got closer I came face to face with an American badger staring at me from the entrance of the burrow. I was getting an extremely strong signal from the burrow, indicating the tortoise that I was looking for was inside!  Badgers are carnivorous and are known to prey on tortoises, so I was concerned for the well-being of our study tortoise. I sat down several meters away to fill out my data sheet, which took several minutes.  I got up to leave and walked over to the burrow to take one last look. Our tortoise was looking right back at me! I guess the badger and tortoise are just two friends sharing a burrow.

My summer as a telemetry technician was filled with ups and downs: hiking, pulling cactus spines out of my legs, amazing wildlife, and awkward tan lines. Now, at the end of the summer, I can say the tortoises are all doing well and have somewhat settled down into homes throughout the site. They are interesting little creatures, and I hope the work we did and the data we documented will help make future projects a success!

Lindsey Perry was a seasonal research assistant at the San Diego Zoo’s Desert Tortoise Conservation Center. Thank you, Lindsey!


A Long Winter’s Sleep

A desert tortoise hatchling heads for a burrow.

It’s that time of year again: the time for desert tortoises to sleep for the winter. As some animals head south for the winter in search of warmer weather, desert tortoises stay in their favorite burrows right here in the Mojave Desert to escape the winter chill. Every year around October, desert tortoises begin to slow down and find a perfect burrow to hibernate in for at least the next few months of winter. At the San Diego Zoo Desert Tortoise Conservation Center (DTCC), we dig artificial burrows for many of the tortoises to make sure they are well protected over winter, and we berm them in by building up a mound of dirt in front of the burrow to prevent cold air and winter monsoon rains from getting in.

Desert tortoise hatchlings have their choice of burrows at the DTCC.

It is not uncommon for the Mojave Desert to receive some rainfall during winter months, and occasionally desert tortoises come out to have a drink. That was certainly the case a few weeks ago when it rained for seven days straight, and we were completely flooded! In most cases, tortoises come out of their winter sleep because of the smell of the rain and creosote in the air, and they either find low-level ground where water has collected, or, in some instances, they actually dig a small impression in the ground so water can pool up for drinking. After their drink, they return to their burrows to sleep for the rest of their hibernation period.

Things are a bit different around here for little desert tortoises, though. As winter approaches, young tortoises are also starting to go to sleep for the winter, but before they can hibernate, we must do a health assessment on them to make sure they are healthy. Neonates (hatchlings from this year) and very young desert tortoises that weigh less than 3.5 ounces (100 grams) and are less than 3.1 inches (80 millimeters) long are kept in special predator-proof enclosures until they are large enough to be moved to an unprotected pen. Every one of the tortoises that is held in these pens must undergo a pre-hibernation health assessment, and this keeps us really busy!

A juvenile desert tortoise enjoys time in the sun.

This winter there are over 400 young tortoises in the predator-proof pens, so it took us two full weeks to assess them all. Luckily, almost all of them were in great condition and were ready for hibernation, but the few that weren’t feeling so well were taken to the medical center for special care over the winter (see post Desert Tortoise Hibernation: Not for All). The best thing for a young desert tortoise to do over the winter is to hibernate; we have seen that young tortoises that are allowed to hibernate outdoors, especially in their first year of life, grow up healthier than those that don’t! But if a little one is not healthy enough to hibernate, then it’s best to allow it to stay inside and awake over winter so he or she can get the care needed before spring.

Daniel Essary is a research associate at the San Diego Zoo Desert Tortoise Conservation Center. Read his previous post, Desert Invasions.


Desert Tortoises Step Closer to the Wild

Can you find the desert tortoise in this burrow?

We recently completed our inventory of all the tortoises on site at the San Diego Zoo Desert Tortoise Conservation Center (DTCC). It took us two full active tortoise seasons, but we did it! (See Pam’s previous post, Counting Tortoises). Although this task has occupied nearly all of our time, we have somehow also been able to move healthy tortoises into our newly designated 20-acre translocation enclosure. Healthy, ELISA-negative tortoises (see post Tortoise Science: Cooler than You Think about ELISA testing) that have remained free of upper respiratory tract disease (URTD) symptoms for at least 30 days will be moved to the translocation enclosure (we call it a “pen”), the final step before being relocated into the wild next spring!

We had to make sure that the translocation pen could accommodate the number of tortoises we wanted to put in it, so our four seasonal research assistants had the task of adding burrows to provide the tortoises with protection from the heat and cold and installing a water delivery system to this pen. Each burrow takes an hour or more for one person to dig, but we have successfully added 50 burrows to this pen over the course of 2 months while still conducting inventory!

We now have over 100 healthy tortoises waiting to be relocated to a U.S. Fish and Wildlife Service-approved translocation site here in southern Nevada! We plan to put radio transmitters and GPS data loggers on the healthy tortoises prior to the long-anticipated release in the spring of 2011. A team of experienced telemetry technicians will follow the signal from these transmitters, allowing us to track and study the movements and habit use of these animals.

Why is translocation into the wild so important? Wild populations of Mojave desert tortoises have reportedly declined by approximately 90 percent in the past 30 years; it is estimated that there are only about 150,000 wild Mojave desert tortoises remaining in critical habitat. The desert tortoise is a keystone species, meaning that it plays a critical role in its environment. How? Desert tortoise burrows serve to protect other desert species from predators and harsh weather conditions, and they disperse seeds from the native plants that they eat, repopulating the desert ecosystem with them.

Our mission is to play a significant role in the conservation of the Mojave Desert, including the recovery of the desert tortoise and its habitat. Through all of our work, including translocation, we are well on our way to fulfilling our mission!

Pamela Cicoria is a research associate at the San Diego Zoo Desert Tortoise Conservation Center.


Watch Where You Step!

A nickle placed on cryptobiotic soil shows how small the lichen is.

The desert soil is alive! Well, the soil itself isn’t really living, but life occurs throughout the soil of the Mojave Desert, so it’s important to always stay on designated trails and roads when you are in the desert.

Small microorganisms called cyanobacteria, which are from the same family as blue-green algae, actually live on the surface of bare soil in the desert. For most of the Mojave Desert, the soil is usually characterized by rough dark patches as shown in the photo, but these cyanobacteria, with the aid of different types of lichens, mosses, and other colonies of microorganisms, can sometimes produce colorful soil crusts. In both cases, the soils are called cryptobiotic crust.

Lichen covers cryptobiotic soil in the Mojave Desert.

Cryptobiotic crust is very important to the health of the desert—a great sign that barren land is actually growing and thriving. In fact, cryptobiotic crust helps produce nutrients and organic material that are recycled back into the soil, and this supports vegetation in the desert. This is great news for all the desert animals, like desert tortoises, that feast on plants as their main source of nutrition. The organic structure of cryptobiotic soil can also help native seeds to germinate (sprout), again an important feature for plant eaters like desert tortoises.

It takes a very long time for cryptobiotic soil to form, and it is also very sensitive to changes in its environment, so when it is disturbed, it does not have an easy time recovering. Some estimates indicate that it takes 250 years for damaged desert habitat to recover! When people use the desert for recreation, they have the opportunity to see and experience some of the most amazing scenery in the world. But if they are not careful, or they purposefully hike or drive off designated trails, cryptobiotic soil can be devastated.

When you step on cryptobiotic soil or drive over it, you kill millions of organisms that support the plant life that desert tortoises eat. If the soil is destroyed, then plants cannot grow, and tortoises will have nothing to eat. So if you know anyone who drives or hikes off trail and they tell you it’s okay because they are always careful not to run over tortoises or their burrows, you can now tell them it’s not okay because they are destroying cryptobiotic soils that allow plants to grow to feed the tortoises that they are being so careful to avoid!

As you can see, cryptobiotic soil is very important to the Mojave Desert ecosystem, and we should make every effort to avoid walking on or touching the soil. The next time you are out on a desert hike or driving down an old desert road, please stay on the designated routes to avoid harming the living soil below you.

Daniel Essary is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center in Las Vegas. Read his previous post, A Desert Tortoise Isn’t Just Any Old Tortoise.