Desert Tortoises

Desert Tortoises

1

Planning a Perfect Desert (Tortoise) Getaway

A desert tortoise is in safe hands during translocation.

A desert tortoise is in safe hands during translocation.

My boots are sitting in the hallway covered in dust. Not from lack of use, I might add. But following such an inspiring field experience in the Mojave Desert, where I released tortoises to the wild, it just seemed too soon to wipe away the dusty memories of my desert adventure.

If you work at a desk most of the time, like I do, you’ll understand that getting out into the field can be a rare and fleeting opportunity. Fortunately for me, my job takes me on walkabout to visit our field programs about once every couple of months. Each trip has a dedicated mission, from delivering vital field equipment to planning field operations alongside remotely based staff, and each trip has the added bonus of bringing me joy in connecting with the animals, people, and places where we work.

On this last trip, my trifold mission was to deliver a brand-new four-wheel drive truck to our Desert Tortoise Conservation Center, assist in a long-planned translocation of desert tortoises to the Greater Trout Canyon area just west of Las Vegas, and take staffer Julie Marshall on a memorable professional training experience. Julie works diligently overseeing our Institutional Animal Care and Use Committee, ensuring all our projects follow the highest animal welfare standards, and this trip would give her the golden opportunity to see our tortoise conservation efforts in action.

Julie Marshall radio tracks a desert tortoise.

Julie Marshall radio tracks a desert tortoise.

Our first day was spent with the staff at the Center, carefully preparing animals for their move to the wild. Each tortoise has undergone a meticulous health screening and testing over the past year to ensure its overall condition will not compromise its chances for survival. Carrying out the finishing touches, we attached radio transmitters to each of the 32 tortoises destined for freedom. The translocation effort serves two main purposes: population augmentation and research. The population of wild tortoises in the Greater Trout Canyon area has been in decline for several years. The translocated animals are expected to bolster the population and, at the very least, slow the decline in numbers. Research includes checking on the released tortoises at regular intervals to determine how they are adapting to their new environment.

Waking uncomfortably early at 4 a.m. the next day, we headed out to meet the staff, volunteers, and members of other agencies (NDOW, FWS, USGS), assisting in the translocation. After a briefing and some quick training in the use of handheld GPS units, we drove off in convoy with our precious cargo. As dawn was breaking, each tortoise received a subcutaneous injection of liquid to ensure proper hydration, and each person, carrying a tortoise in a tote, navigated to a target GPS location to make a “drop”. Fanning out across the desert landscape, our work was accomplished swiftly in the cool morning air, some tortoises remaining still until we left their sides, others trotting off into the near distance. We all left wondering, what next?

Our third and final day started just as uncomfortably early as day two and focused on finding out what next. While I caught up on center operations, Julie accompanied our field technicians to learn how to radio track tortoises. Hiking across the desert terrain following the beeping sound of an animal’s transmitter is tough work, but the payoff when you find an animal is exhilarating. After animals are translocated, they often make longer-range movements than normal in exploring their new environment, so it is key for us to follow them closely during their first few weeks of release so we don’t lose anybody.

I’m happy to report all tortoises were relocated, and I’m grateful that my job involves working with the dedicated members of the Desert Tortoise Conservation Center team who are making conservation happen and who are all infinitely better morning people than I!

Allyson Walsh is an associate director in the Applied Animal Ecology Division of the San Diego Zoo Institute for Conservation Research.

2

Tortoise in the Glass: Evaluating Health Problems

To you, a typical tortoise might look like this:

desert tortoise adult

But to me, a tortoise may also look like this:

desert tortoise tissue samples

I’m a veterinary pathologist, which means I spend a lot of quality time looking through a microscope at slides with tissues to try to evaluate health problems that show up as changes in those tissues. I can find dying cells, inflammation, various pathogens, scarring, thinning, thickening, bleeding, tumors, strange crystals, and unusual pigments. All of the changes help us understand the health problems affecting an animal.

At the San Diego Zoo Institute for Conservation Research, I work exclusively on tortoises that have died at the Desert Tortoise Conservation Center. Why bother? Well, it turns out that one of the best ways to figure out what health indicators most accurately indicate disease is to compare the information from the live tortoise to the changes we see in the tissues if the animal dies. The more we know about which tools work to predict severity and type of disease, the faster and more precise we are at identifying and helping animals at risk.

To get information from enough tortoises to allow good conclusions to be drawn, I need to look at a lot of slides. Since 2009, over 4,500 slides have been made of desert tortoise tissues, providing an invaluable resource for the understanding of disease in desert tortoises. Since November 2012, I’ve been describing the changes I see so that they can be correlated to what was found in the live animal. Thankfully, I haven’t been working all alone; Dr. Lily Cheng, another veterinary pathologist, volunteered to spend two whole months staring at a mountain of desert tortoise slides. Between the two of us, we’ve done more than 3,000 slides belonging to over 250 tortoises!

Are you curious about what sorts of things we see? Good! We are always on the lookout for bacteria or viruses that cause that most feared of tortoise infections: upper respiratory disease. This is more than just a head cold like people get and is a big factor in tortoise population decline. Some savvy souls may note that no light microscope can show an individual virus particle (you really need an electron microscope for that, since viruses are smaller than the wavelength of visible light). Conveniently, however, some viruses clump together to form rafts of virus particles. These are big enough to see with a microscope, just as you can see a patch of lawn even if you are too far away to pick out a single blade of grass. The virus most common and dangerous in tortoise respiratory disease (herpesvirus) forms these aggregations in the nuclei of cells, and they are called intranuclear inclusions.

Below are some cells from a tortoise that had severe upper respiratory disease. On the left side of the picture, you can see normal nuclei: round or oval purple shapes that look very speckled, like chocolate chip cookies. On the right side of the picture, the nuclei are bigger and have clumps of magenta in the center surrounded by a clear rim. They no longer resemble chocolate chip cookies at all. Those magenta blobs are viral inclusions from herpesvirus!

Herpes inclusions

The work continues at a good pace, and there are only about 1,300 slides left to look at. They weigh almost 7 kilograms (15 pounds) altogether. Wish me luck!

Kali Holder, D.V.M., is a postdoctoral associate in the Wildlife Disease Laboratories for San Diego Zoo Global.

3

Time for Tortoise Training

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.

2

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.

3

White Christmas for Juvenile Desert Tortoises

A tortoise burrow can be seen the morning after a nightfall of light snow. desert.

A tortoise burrow can be seen the morning after a nightfall of light snow. desert.

Juvenile desert tortoises released in September 2012 at the Nevada National Security Site are making their way through their first winter in the wild. The tortoises were snug tight in their burrows over the holidays when temperatures dropped below freezing and a light snow fell.

As ectotherms (cold-blooded animals), desert tortoises must utilize their surroundings to regulate their body temperature since they can’t warm their bodies on their own. Only a few inches of soil are enough to buffer air temperatures to allow the tortoises to hibernate through the winter without freezing. In a few more months, when the air temperatures begin to rise here in the desert, all of our translocated tortoises should emerge to heat themselves in the sun.

Jeanette Perry is a research assistant at San Diego Zoo Global’s Desert Tortoise Conservation Center in Las Vegas, Nevada. Read her previous post, Wandering Males, Jealous Boyfriends.

3

Internship at Desert Tortoise Conservation Center

Our student interns help desert tortoise conservation in a big way!

Our student interns help desert tortoise conservation in a big way!

Throughout 2012, the staff at the Desert Tortoise Conservation Center worked with students from a local high school, West Career & Tech Academy (see Students Help Desert Tortoises). The students were very interested in science and receiving hands-on experience, and we were happy to help out any way we could to expose the students to real-world experiences and to gain a little help of our own. West Tech started an internship program and asked us to participate; we, of course, were happy to help and keep the partnership alive. We thought of a number of projects the interns could work on and found the perfect fit. Our first interns, Gendie Gonzales and Cheyenne Taylor, were interested in participating in duties at the DTCC, but since it’s winter here, we had to come up with an indoor project that would benefit all.

The sample-filled tubes await organizing.

The sample-filled tubes are organized and banked, thanks to our interns.

An experienced biologist had collected over 4,000 biological samples (such as plasma, red plasma, red blood cells, ticks, and oral swabs) from desert tortoises at various Mojave Desert sites over the past summer. We needed help banking or organizing all the sample-filled tubes that were in plastic bags with a date on them when given to us. Banking these important samples is not an easy task and takes a lot of time and meticulous effort to ensure no mistakes are made. These samples are important, because they will be around for a long time and will help give us invaluable information about wild desert tortoise genetics and health.

The internship is a great way to give students a look into a career in conservation biology and give us a helping hand at the DTCC. We look forward to the continuing partnership in 2013!

Angie Covert is a research coordinator at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Promoting Desert Tortoise Care.

1

Desert Tortoise: Winter Improvement Tips

A desert tortoise patrols its backyard habitat.

As the temperature drops outside and desert tortoises are slumbering in their burrows, we here at the Desert Tortoise Conservation Center are busy catching up on projects around the site. This is also a perfect time for desert tortoise custodians to work on home projects and make habitat improvements for their own pet tortoise in preparation for the spring emergence. You might be a seasoned tortoise custodian or just getting started; either way, here are some simple and helpful tips for making the home habitat safe and interactive for your tortoise.

Tip 1: Escape-proof Your Yard
When a pet desert tortoise escapes from a yard, it isn’t usually a family member that leaves a gate open but a gardener or meter reader that didn’t know a tortoise was in the yard. Unfortunately, once a pet tortoise escapes, it is not always easy to reunite him with the custodian. An easy fix for preventing this mishap is to add a simple and removable gate barrier. The barrier should be at least 18 inches high and made of a solid material. A large piece of particleboard is a good option, which can be secured by placing four cinder blocks (one on each side) on both ends of the board. This design works great, especially if there is a need for the board to be removed temporarily. Once the gate barrier is in place, take a look at the entire fence line and make sure it is secure and free of holes or breaches.

Tip 2: Eliminate Hazards
Bundle up with a scarf and a pair of gloves and enjoy some family time, outdoors! This is a great time of year to clean up your yard and look for hazards that may harm your tortoise. Desert tortoises are excellent climbers, and they may try to climb over piles of debris or unused equipment, which can be hazardous if the tortoise falls backward, getting trapped on its “back.” Look for other hazards to fix, like an unfenced pool or water feature, which a tortoise could fall into. By sprucing up your yard this winter, you can make it a safer environment for your family pet this spring!

Colorful globemallow is a favorite food of the desert tortoise.

Tip 3: Spring Planting
Spring is right around the corner, so now is a great time to start thinking about greenery you can add to your yard when the weather warms up! Desert tortoises are natural foragers, and they love to roam the yard munching on plants and grasses. Tortoise- friendly forage such as globemallow, primrose, hibiscus, and Bermuda grass will help provide your pet tortoise with the right nutrition throughout the active season. Check with your local nursery for availability and growing recommendations for your climate.

Lori Scott is a research associate at the San Diego Zoo Desert Tortoise Conservation Center. Read her previous post, Desert Tortoises Spotlight Teacher Workshop.

1

Tortoises Spotlight Teacher Workshop

Workshop participants find a “tortoise” using radio-tracking equipment.

As we close in on our winter season at the Desert Tortoise Conservation Center, located in Las Vegas, Nevada, it’s a great time to reflect on some of the highlights of our busy summer. One new program we offered to local teachers through the Clark County School District was a desert tortoise education workshop. This past June and July, a total of 32 teachers took part in the workshops. We’re happy to report that the classes were well received, and the response has been very positive!

Although rarely seen in the wild, the desert tortoise is the state reptile of Nevada and an important keystone species of the Mojave Desert ecosystem. Getting kids excited about science and math can be a huge hurdle for many teachers, and this was one of our main motivations for developing the desert tortoise workshop. One of the goals of the workshop was to provide teachers with curriculum that spotlights the cool adaptations of the desert tortoise while focusing on the important roles it plays in the Mojave Desert. With a focus on biology, ecology, and conservation, teacher participants were provided with fun and interactive desert tortoise curriculum, which also fulfills the Nevada classroom standards in life and earth sciences.

Throughout the workshop, teachers became students and were able to participate in hands-on activities and demonstrations to simulate current research projects being conducted by San Diego Zoo scientists. For example, teachers participated in a telemetry demonstration, learning hands-on how researchers use telemetry to study tortoise behavior following a release back into the wild. As a part of the activity, participants used radio tracking-equipment to “track” a model tortoise (made of Styrofoam), which had been affixed with a radio transmitter and hidden under vegetation. It was fun to watch a group of educators weave their way through the desert in unison, following the sound of a radio receiver, which released a “ping” as the Styrofoam tortoise grew closer.

Educators who participated in the workshop earned one credit toward professional development education through the Clark County School District, and were provided with desert tortoise resource materials and activities, which can be adapted to their individual grade levels. After a successful first run, we will be offering the workshop again to local teachers in February 2013. We’re excited to provide educators with the opportunity to study the desert tortoise and return to the classroom with a range of tools to promote continued education of this amazing animal and the Mojave Desert ecosystem.

Lori Scott is a research associate at San Diego Zoo Global’s Desert Tortoise Conservation Center. Read her previous post, Desert Tortoises Pose for Photos.

5

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.

8

Wandering Males, Jealous Boyfriends

Jeanette removes a transmitter from one of the released desert tortoises.

We’re currently at the tail end of one of our desert tortoise translocation projects. It’s finally time to say goodbye to the desert tortoises we have been tracking for the past year and a half, and over the past month or so we’ve begun the task of removing their transmitters. However, this is easier said than done. This project happened to end during the mating season, a time when males move long distances in search of females. One of our males went missing for five weeks and was found almost three miles from his old burrow!

Before we remove the transmitters, we do a final health assessment. We noticed damage to the underside of the carapace (the top shell) on many males. They are known to fight other males utilizing their gular horns to attempt to flip their opponent onto their back. Some male tortoises are bolder than others, and we came across a very bold resident male searching for a female one sunny morning. As my coworker, Jason Rose, and I approached a burrow that female tortoise #619 was occupying, we heard movement inside the burrow. Assuming it was the female we were tracking, we checked the burrow and saw a male tortoise charging at us! He came straight out of the burrow and blocked its entrance, trying to keep us away from his mate. His chin glands were enlarged, and he looked mad!

Here is tortoise #619′s very ardent and determined suitor.

Jason put some gloves on and moved him 50 meters (165 feet) from the burrow so we could get to the female. While waiting for the female to come out of the burrow, the male snuck up behind us and attempted to re-enter the burrow. This time we moved him 100 meters (328 feet) from the burrow to give us some time with the female. Moments later, the male returned and charged Jason. Knowing the female was not going to exit the burrow with the aggressive male in the area, we packed up and allowed the male to re-enter the burrow. He positioned himself facing toward us, in front of the female. Claiming defeat to the jealous boyfriend, Jason and I left the site.

Jeanette Perry is a research assistant at San Diego Zoo Global’s Desert Tortoise Conservation Center in Las Vegas, Nevada.