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San Diego Zoo’s Desert Tortoise Conservation Center

1

Tortoises: Into the Wild

By
Ben Jurand
– May 30, 2013Posted in: Animal Stories, Animals and Plants, Conservation, Desert Tortoises, Projects in the Field, Reptiles and Amphibians, Uncategorized
Each released desert tortoise had a radio transmitter fixed to its carapace with epoxy.

Each released desert tortoise had a radio transmitter fixed to its carapace with epoxy.

It began early in the morning, before the sun peeked over the mountains. The Desert Tortoise Conservation Center (DTCC) in Las Vegas was abuzz with activity as we prepared 32 desert tortoises for the journey of a lifetime. Little did these animals know that they were about to be brought to a new home. Many of them had been living at the DTCC for several years; some had even begun their lives as pets. Now, these tortoises would be released into the wild to try to help bolster the native populations as well as give them the chance to live their lives as wild tortoises.

When the tortoises were ready, we carried each to a preset location and placed it in a sheltered spot under a shrub.

When the tortoises were ready, we carried each to a preset location and placed it in a sheltered spot under a shrub.

After placing the tortoises in hay-lined totes, we loaded them into trucks and headed to Trout Canyon, a beautiful piece of Mojave Desert habitat over the mountains to the west of Las Vegas. Once on site, the tortoises were administered fluids to help them stay hydrated in the first weeks in their new home. We double-checked the frequencies of each tortoise’s radio transmitter to ensure we would be able to track them in the field over the coming weeks and months.

We watched the tortoises for several minutes after releasing them to see how they reacted to their new environments. As you might expect, many of them were reluctant to move for a little while, but some took to walking and started exploring their new home right away!

In the four weeks that have passed since the translocation, we’ve tracked the movements of all 32 tortoises we released, as well as 20 tortoises that were already living there. Some tortoises have stayed relatively near their release sites, exploring only about one or two football fields’ worth of the new neighborhood.

Caliche caves can act as rock burrows for tortoises, protecting them from predators and the elements.

Caliche caves can act as rock burrows for tortoises, protecting them from predators and the elements.

Shelter is a prime concern for tortoises, as they need to protect themselves from extremes of temperatures (both hot and cold) and from would-be predators like coyotes or ravens. Many of the tortoises we released have found temporary shelter under shrubs like creosote or white bursage and continue to move around in a relatively small range.

A few tortoises are taking up residence in existing burrows near their release site. The burrows may be abandoned or are occupied by accommodating neighbors. When suitable unoccupied burrows are unavailable, a few industrious tortoises have begun to dig their own.

Other tortoises have taken up shelter in caliche caves. One of the tortoises found the nearest cave to its release site and stayed there for over two weeks. Then, one day, he decided to start moving and has been walking for the past few days about a third of a mile (half a kilometer) a day.

We have tracked other tortoises traversing the landscape walking miles away from their release sites. They have covered rough terrain from windy creosote flats to rocky washes and steep mountain ridges. The end of the spring growth has provided some forage for the tortoises, and they need to take advantage and gather resources now before the heat of summer dries up the best nutrient sources.

We found a desert tortoise egg just outside a burrow.

We found a desert tortoise egg just outside a burrow.

Although the race is still on for who has traveled the farthest, one tortoise in particular has certainly moved with a purpose. She scaled steep rocky ridges and deep washes only reach the top and decide to cross the next ridge to the north. After weeks of walking, she finally took a few days off to rest. Apparently she had a mission in mind, as today we found her nesting under a blackbrush on a steep mountain ridge. She had already laid one egg; we could see it just outside the burrow!

The next few weeks will be important for the tortoises as the females continue to nest and they all settle in for the heat of summer, when they will only be active in the coolest parts of the day. Finding or building burrows in the soil or rocks is very important, as is foraging. A good rain or two would help bolster their water supply for the season, but we can only wait and see what the weather brings!

Ben Jurand is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center. Read his previous post, Time for Tortoise Training.

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3

Time for Tortoise Training

By
Ben Jurand
– April 11, 2013Posted in: Animals and Plants, Conservation, Desert Tortoises, Projects in the Field, Reptiles and Amphibians, Uncategorized
Ben prepares to take a blood sample from a desert tortoise.

Ben prepares to take a blood sample from a desert tortoise.

The Desert Tortoise Conservation Center (DTCC) in Las Vegas, Nevada, is gearing up for the spring translocation of a number of desert tortoises. We will be moving tortoises from the DTCC to a field location in the desert, where we will release them to help augment struggling wild populations.

Translocation is stressful on tortoises, because they need to adapt quickly to new surroundings, find shelter, and keep a lookout for both resources and predators. To give translocated tortoises the best chance of surviving in the wild, we need to make sure the animals are healthy and strong enough to be released. We also need to try to prevent them from spreading diseases to other tortoises in the wild.

As a new research associate at the DTCC, my first week included a lot of training. We were lucky to have several desert tortoise researchers and veterinarians visit from the U.S. Fish and Wildlife Service and San Diego Zoo Global to provide hands-on instruction on how to visually assess the health and condition of tortoises. We also learned how best to gather data and collect samples, including how to take oral and blood samples from the tortoises to test for diseases. We learned how to measure the size and weight of each tortoise, made notes about how their facial features and shells looked, and checked them for injuries or signs of illness.

DTCC staff take desert tortoise measurements.

DTCC staff take desert tortoise measurements.

Knowing their condition before we move them will help us track their progress over time in their new wild habitat. On some of the tortoises, we will be attaching radio transmitters to the upper part of their shell (called a carapace). After we have translocated the tortoises, we’ll be tracking their movements in the field and will monitor their health conditions in the days, weeks, and months ahead.

It is our hope that by continuing these studies, we will get a better understanding of how translocations affect the desert tortoises we move as well as their new tortoise neighbors.

Ben Jurand is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center.

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5

Rain in the Mojave Desert

By
Daniel Essary
– November 15, 2012Posted in: Animals and Plants, Conservation, Desert Tortoises, Plants, Reptiles and Amphibians

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.

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Desert Tortoise CSI

By
Larisa Gokool
– August 16, 2011Posted in: Animal Stories, Animals and Plants, Conservation, Desert Tortoises, Reptiles and Amphibians, Uncategorized

"Detective" Larisa prepares for a necropsy.

The scene:
The hot, arid Mojave desert. Yuccas and Joshua trees sparsely dispersed in the foreground. Yellow “caution” tape surrounding the affected area. Photographs being snapped with numbers and rulers.

DTCC research associate:
The victim (adult male tortoise) was found lying in dorsal recumbancy (on the carapace) in front of an empty manmade burrow, urates on the plastron and ground. A fellow male and female tortoise look on from the corner of the tortoise pen.

DTCC pathology tech:
Looks like a case of love……gone wrong … YYYEEEAAAAAAHHHHH!!

Okay, okay, that’s not how my day actually plays out when a dead tortoise is found on site, which luckily isn’t too often, but we do have a pseudo-CSI department here at the San Diego Zoo’s Desert Tortoise Conservation Center (DTCC).

The tools of the trade we use in conducting our CSI activities, all set up in the necropsy trailer. The Mojave Desert can be seen through the window

If and when a tortoise is found dead on site, or needs to be humanely euthanized due to a debilitating illness or severe injury, it is immediately brought to the pathology trailer for necropsy. A necropsy is an animal autopsy, and it is performed by me, the pathology technician, as proxy for our pathologist who is based at the San Diego Zoo’s Wildlife Disease Laboratories. The necropsy helps determine the cause of death by examining body lesions or changes in tissues.

I begin a necropsy by verifying the death and identification of the tortoise, taking external measurements (weight, size, etc.), and noting any abnormalities seen on the exterior portions of the tortoise. After the external examination, I perform the internal examination, inspecting the organs, muscles, and joints, taking representative samples from each section for molecular diagnostics and histology. For histology, very thin-cut sections of these tissue samples (~10 µm thick) are mounted and stained on glass slides for microscopic examination of cells, structures, and immune response cells not visible to the naked eye. For molecular diagnostics we isolate DNA out of the tissue samples for real-time PCR, used to detect microorganisms. The samples, along with my gross descriptions (not gross as in disgusting, but gross as in overall) and photographic documentation of the case are sent to the pathologist, who will then interpret all of this information to make a diagnosis of why a tortoise died or the main cause of disease if it was euthanized.

A desert tortoise undergoing necropsy to determine the cause of death.

Necropsy is a very useful tool for maintaining the health of a captive population, especially for an animal listed as an endangered species, such as the desert tortoise. By conducting necropsies, we have the opportunity to learn from the unfortunate death of an animal on site. We can see tissue proliferations, severe inflammation, and abscesses that are not externally visible in areas such as the lungs. We also inspect changes to the nasal cavities, an area frequently affected by Mycoplasma agassizii, one of the leading causes of upper respiratory tract disease in tortoises. We can see an excess in production of mineral deposits, such as uroliths (bladder stones) within the urinary bladder that are too large for the animal to pass so they cause a blockage. We can also see endoparasites present within the GI tract that we can sample for identification.

Identifying infectious diseases and disease-causing agents is the first step toward mitigating disease in the remaining population and establishing screening tests. Thus, by investigating the deaths at the DTCC we are able to make more informed decisions regarding how to provide the best care for these animals that are destined to augment the dwindling wild populations.

Larisa Gokool is a research associate at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Meeting Galápagos Tortoises.

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Desert Tortoises Pose for Photos

By
Lori Scott
– August 3, 2011Posted in: Animal Stories, Animals and Plants, Conservation, Desert Tortoises, Reptiles and Amphibians, Uncategorized

Desert tortoise Homer with Seymore, one of his new family's cats.

The morning sun is barely peeking above the horizon, and magnificent purple and orange rays of light begin to cascade over the entire Mojave Desert. I’m trying to get in as many snapshots of adoptable tortoises before the intense desert heat sets in. Each photo is important, and I know I’m running out of time as a thin bead of sweat drips down my neck: it will only be minutes before tortoises begin to disappear beneath the earth into their cool burrows. Maybe the impressively large male tortoise I’m trying to get the perfect picture of would wait a second longer if he only knew these photos could change his life. “Photos of hope” I like to call them, displaying the unique and charming characteristics of adoptable tortoises that reside at the Desert Tortoise Conservation Center (DTCC), located in Las Vegas.

With approximately 1,000 tortoises coming to the DTCC through the Pet Desert Tortoise Hotline each year, it would be easy for them to blend together. However, there are quite a few tortoises that stand out in my mind. Homer, a petite adult male tortoise with a big personality, can be added to my lasting impression’s list. He recently found his forever home with his new custodian, Mandy, who had the opportunity to pick Homer from an adoption packet with tortoise photos and descriptions. Without actually seeing his cute face and curious demeanor in the photo, Mandy might have missed the opportunity to adopt Homer and make him part of her family.

Homer comes over to greet Oliver.

An otherwise healthy tortoise, Homer has a mild beak deformity, which does require supplements of soft food in his diet in case he is unable to eat some of the native forage provided in the yard. Mandy is finding out every day what a joy Homer is to have, and she was excited to send some fun photos of him with his new feline family members, Seymore and Oliver. Seymore especially likes to hang out just above the opening to Homer’s burrow and wait for him to come out and play when the weather is nice (see above). Mandy also tells me the whole family loves watching Homer go about his daily activities in the yard, and she has occasionally found him in the house after finding his way inside through an open back door!

Our main mission at the DTCC continues to be recovery of wild desert tortoise populations in the Mojave Desert. However, I’m hoping folks will see the benefit of adopting a tortoise that is not eligible for release but would make a great addition to a caring and loving home! Tortoises that are eligible for adoption are healthy and social animals that may have been someone’s pet or tortoises with mild physical abnormalities. Through Tortoise Group, the only U.S. Fish and Wildlife Service-approved adoption program in southern Nevada, conservation-minded custodians can provide loving homes for tortoises in need that currently reside at the DTCC while advocating on behalf of a threatened species, helping us to spread the word regarding desert tortoise conservation in southern Nevada.

If you want to have a desert tortoise as a pet, and you live in southern Nevada, you can contact Tortoise Group for information on how to adopt one; there are no other legal means of obtaining one outside of Tortoise Group.

Lori Scott is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center. Read her previous post, Pet Desert Tortoise Hotline: Educational Outreach.

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3

Desert Tortoise: Hot! Hot! Hot!

By
Daniel Essary
– July 27, 2011Posted in: Animal Stories, Animals and Plants, Conservation, Desert Tortoises, Reptiles and Amphibians, Uncategorized

A desert tortoise seeks shade in a man-made burrow.

Summer months are the best times for people to get out and enjoy the great outdoors, to go swimming, or to just to relax, but for the desert tortoise, it is time to get some much-needed rest. For most animals the summer season is the time to be productive in life by gathering food, finding a mate, or even establishing a home territory. But the Mojave Desert’s summers are harsh, making it difficult to be active with temperatures reaching well above 105 degrees Fahrenheit (41 degrees Celsius) and with very little (if any) rain. The desert tortoise is well adapted to deal with such extreme weather by going into estivation during the extreme heat of the summer.

Estivation (from the Latin word aestas, meaning summer) is a state of summer dormancy similar to winter hibernation, but in summer estivation, tortoises don’t sleep all the time. In most instances, the tortoises are active for a few hours during the morning and retreat back to a favorite burrow to sleep through the day. As dusk approaches, the tortoise  leaves the burrow for a few hours to eat or drink before night falls. In some cases if there are cooler days or even monsoonal rains, the tortoises come out of their burrows to take advantage of the rain and cooler temperatures. But during the months of June through the end of September, desert tortoises mostly remain inside their favorite burrows for summer sleep so as not to use up energy unnecessarily.

Desert tortoise hatchlings at the entrance to several burrows

We are currently conducting an experiment at the Desert Tortoise Conservation Center that may benefit the well being of the desert tortoises on site. We are doing a burrow temperature study that will help determine if the artificial burrows we dig for tortoises maintain the same temperatures as burrows that tortoises dig themselves. Since tortoises spend 95 percent of their lives in burrows, this is very important information for us to know! We placed temperature data loggers in both natural and artificial burrows and set them to record temperature throughout the day.

By analyzing the temperatures in both artificial and natural burrows, we will find out if we need to change the way we dig the artificial burrows so that tortoises can comfortably estivate in summer and hibernate in winter. If temperatures are too high inside the burrow, the tortoise living inside it can get very sick, or even die, so we want to make sure that every burrow we dig provides them with all the protection they need from the harsh heat of the Mojave summer.

Daniel Essary is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center. Read his previous post, A Long Winter’s Sleep.

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16

Desert Tortoise: NOT Apartment-friendly Pet

By
Lori Scott
– July 26, 2010Posted in: Animal Stories, Conservation, Conservation at the Zoo, Desert Tortoises, Reptiles and Amphibians

A desert tortoise in its natural habitat.

I’m happy to say the Pet Desert Tortoise Hotline is giving us the opportunity to save more stray and unwanted desert tortoises and educate folks on the proper care for their pet tortoises. Manned by staff at the San Diego Zoo’s Desert Tortoise Conservation Center (DTCC) in Las Vegas, we’re also really excited to have a new employee join the team! Marissa Musso has come on board as the hotline assistant, and she’s doing a great job out on the front lines educating and working with the public. Marissa’s excellent people skills and cheerful demeanor have been a great asset for many of our hotline calls, especially when we’re faced with challenging cases of extreme pet desert tortoise neglect.

A desert tortoise enters a manmade burrow at the DTCC.

For each hotline call that comes in to the DTCC, it’s always a coin toss for what we’ll find at the actual pickup site. Sometimes we knock on the door and see great examples of the awesome care tortoises can receive in a home, especially when the custodian is providing the proper diet and environment. Simply put, a healthy and happy pet desert tortoise is living outside with lots of natural sunlight in a spacious yard with a burrow and plenty of native plants to eat like desert dandelion, globemallow, and desert primrose. Unfortunately, more often we see sad cases of extreme tortoise neglect, some that require a large box of Kleenex at the end of the day. This has been the case with several pickups we’ve done recently at apartment buildings.

The Mojave Desert is known for its extreme temperatures, and Las Vegas is no exception, but one spring day several weeks ago was one of the rare few that rested in the 80-degrees Fahrenheit (27 degrees Celsius) range. It was a perfect day, until I received a hotline call from a person living in a small apartment with three desert tortoises. I was shocked to learn one of the tortoises had recently died from an apparent case of predation; all three had been living on a small, concrete patio with a cardboard box for a “burrow.” The caller informed me that the largest tortoise had been killed by a raven, and he wanted to surrender the other two. What made this even more upsetting was that I had already visited this caller and had tried to educate him on how important it is for a pet tortoise to have a yard with a burrow. In fact, a desert tortoise spends 95 percent of its life in a burrow where it gets protection from harsh weather and predators.

Even after desperately trying to explain how his tortoises would not survive the summer living on a 2’ x 4’ patio and hoping he would surrender them to the DTCC, the custodian still decided to keep them. You can imagine what a hard day it was, having to leave empty handed and knowing both tortoises would have a slim chance for survival. So when I got the call to pick up the remaining two, I quickly drove to the apartment only to find them in even worse condition.

Both tortoises could barely move; all of their limbs were hanging out of their shell. They had labored breathing and could hardly open their eyes. Before giving the caller any time to change his mind, I scooped them up and drove them quickly back to the DTCC, wishing that our hotline vehicle was equipped with an ambulance siren. After being evaluated by our veterinarian, it was determined that these animals had been suffering for years and were only barely alive by the time I had picked them up. They were in advanced organ failure with no hope of living a comfortable life, all because they lived on a patio with no burrow and inadequate heat and light from the sun.

All of this could have been avoided had the custodian realized he couldn’t provide the right environment for a desert tortoise. When a desert tortoise is living in the wild in our wonderful Mojave Desert, they take great care of themselves. But as pets, tortoises depend on us to care for them and provide the right diet and environment. As most responsible custodians know, caring for a desert tortoise properly can be quite time consuming and extensive; they don’t make the best pet for every situation.

If you have or know someone who has a desert tortoise living on a patio or in a terrarium in southern Nevada, please consider surrendering them to the DTCC. This decision could save a tortoise from months or years of misery, and all it takes is one quick phone call to the Pet Desert Tortoise Hotline!

Lori Scott is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center. Read her previous blog, Desert Tortoise: Big Guy.

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10

Desert Tortoise: Big Guy

By
Lori Scott
– April 13, 2010Posted in: Animal Stories, Conservation, Conservation at the Zoo, Desert Tortoises, Reptiles and Amphibians

Lori and Big Guy

I recently joined the San Diego Zoo’s Desert Tortoise Conservation Center (DTCC) as the hotline coordinator, and my first few weeks have been quite a whirlwind! The highlight of my new position came with the very first call I took; that’s how I met Big Guy, a very special desert tortoise.

Although I’ve taken many calls since then, I can honestly say I was a bundle of nerves when my first call came in. As I answered the phone, I could hear in her voice that the caller was a bit nervous, too.

Mona had a pet desert tortoise, affectionately named Big Guy, that she could no longer care for, and she was looking for a place that could take him.

Big Guy’s story with Mona and her family actually started about 25 years ago when her parents were driving on a California highway. They saw him on the side of the road and decided to take him home as a pet (note: taking a desert tortoise is now against the law and has been since the tortoise was listed as a threatened species in 1989). Ten years later, with Big Guy in tow, the family relocated here to Las Vegas (note: it is now illegal to transport desert tortoises across state lines). But now Mona is unable to continue caring for Big Guy. Both of her parents have passed away, and she’s forced to sell their home, the only home Big Guy has known for the last 15 years!

Big Guy rests in front of his new burrow.

After hearing Big Guy’s story, I could understand how hard it is for families to give up their pet tortoises that they love so much. Throughout our phone conversation I tried to assure Mona that Big Guy would do great at the DTCC. I explained that the facility sits on 222 acres of natural desert landscape, and Big Guy would have lots of native plants to munch on! He would also have his own burrow and a dedicated staff caring for him. But it was only after finding out that the DTCC is now operated by the San Diego Zoo that Mona agreed this would be the best home for her beloved desert tortoise!

The next day, I arrived at the home ready to meet Big Guy and hear more about his journey. During my visit with Mona, I was happy to learn that while living with her family, Big Guy had continued to do what tortoises do best: eat native plants like dandelion greens and brumate (hibernate) each year in a well-constructed burrow. After asking a few more questions, I estimated that Big Guy must be at least 40 to 50 years old! Over the years, he had also picked up an interesting habit: Big Guy learned to knock at the back door with his beak when he wanted to join the family inside! I’m happy to say Big Guy is now making himself at home at the DTCC, enjoying our beautiful desert landscape and coming out of his burrow to bask in the morning sunlight!

Although Big Guy has had a wonderful life with Mona’s family, I want to take this opportunity to remind you that the desert tortoise is a threatened species, so it is unlawful to touch, take, harm, or harass a wild desert tortoise. Please: never pick one up off the road unless it’s to move it out of harm’s way—it must stay in the desert. It is also unlawful to cross state lines with a desert tortoise. Tortoises that come from different areas of the Mojave Desert are actually genetically different from each other, so it’s important to keep them in their native range where they can thrive.

In addition, it is a common misconception that you can give away your tortoise if you don’t want it any more, but in the state of Nevada, it is unlawful to give away your desert tortoise, no matter how long you have had it, and no matter how old it is, unless you are turning it over to the DTCC. If you want to have a desert tortoise as a pet, you can contact Tortoise Group (http://www.tortoisegroup.org) for information on how to adopt one—there is no other legal means of obtaining one outside of Tortoise Group. But remember: if you decide to adopt a desert tortoise, the animal has very specific food and habitat requirements and can live to be 100 years old, so be completely sure you are ready for that kind of commitment! If you live in southern Nevada, and you can no longer care for your desert tortoise, please call the Pet Desert Tortoise Hotline.

Lori Scott is a research associate and hotline coordinator for the San Diego Zoo’s Desert Tortoise Conservation Center. Read a previous DTCC post, Tortoise Staff on Stage.

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0

Tortoise Staff on Stage

By
Pam Cicoria
– April 5, 2010Posted in: Conservation, Conservation at the Zoo, Desert Tortoises, Events at the Zoo, Reptiles and Amphibians

A desert tortoise at a burrow.

A few weeks ago, the San Diego Zoo’s DTCC (Desert Tortoise Conservation Center) staff excitedly loaded up the Ford Explorer and headed to Ontario, California, for a weekend-long symposium hosted by the Desert Tortoise Council. Every year at this time, a wide range of interested people, agencies, and organizations gather to discuss desert tortoise research, to share information, to spend time with colleagues, and to brainstorm solutions to the problems facing this threatened species.

Participants presented fascinating research dealing with health issues affecting tortoise populations, environmental threats to the tortoise, the potentially harmful effects of ambitious renewable energy projects on desert tortoise habitat, and the genetic differences between geographically distant populations of desert tortoises. There was much for all of us to learn!

This wasn’t just any conference for DTCC staff, though; it was a special occasion for us—the first time that we made a public presentation together. Each of us spent five to seven minutes presenting different aspects of the DTCC, showing the improvements we have made during our first year on site, presenting on-site tortoise inventory data, explaining the role of San Diego Zoo veterinarians and other zoo-based staff at the DTCC, and detailing our future plans for the facility.

The audience seemed most interested in the part of our presentation that detailed pet tortoises and captive care, because most people in attendance only had experience with wild tortoises and had never before witnessed the results of poor pet tortoise care (see post Family Dog Loves Pet Tortoise Too Much?). We also shared our great news about taking over operations of the pet desert tortoise hotline (see post Desert Tortoise Hotline). The audience had several questions for us, and people were eager to meet with us after the session had ended.

Although it took some of us out of our comfort zone to get up in front of a room full of people (100+ people were there!), we were welcomed warmly, and we are really proud that we were there to represent both the DTCC and the San Diego Zoo. We are looking forward to the meeting being held on our home turf in Las Vegas next year!

Pam Cicoria is a research associate at the San Diego Zoo’s Desert Tortoise Conservation Center.

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0

Watch Where You Step!

By
Daniel Essary
– March 17, 2010Posted in: Conservation, Conservation at the Zoo, Desert Tortoises, Reptiles and Amphibians

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.

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