Sand and Scales: Fieldwork in the Mojave Desert



Authored by Ben Stegenga

Back in August of 2015, I accepted a job with the Great Basin Institute doing Mojave Desert Tortoise (Gopherus agassizii) telemetry and line-distance surveys. I was part of a 15 person crew, and we were stationed at various sites in southern Nevada and California. The surveyors stayed at our main field site and walked transects looking for tortoises to fit with temporary radio transmitters, while the three of us telemetry techs rotated between several sites tracking transmitted tortoises. Many of the tortoises on our sites were translocated individuals, so the ultimate goal of the project was to locate and track a large number of local and translocated tortoises until they underwent full health assessments. MojaveThe results of the health assessments would offer important insight on the success of the translocation efforts and would be considered in future efforts to create corridors connecting that population to a neighboring tortoise population. For most of three months, I lived in the Mojave Desert, tracking tortoises and sleeping on my foam Therm-a-Rest under the stars. It was physically demanding work, but I loved it. On a typical day, I would get up before sunrise (usually to the sound of coyotes) and track tortoises until late afternoon or evening, often walking 10-15 miles a day. I’d then return to camp, cook supper, lay out my “bed”, and spend the rest of the night exploring the nearby desert by flashlight. Those were some of my favorite times in the desert. I would regularly see Giant Desert Hairy Scorpions (Hadrurus arizonensis), Desert Tarantulas (Aphonopelma chalcodes), Kangaroo Rats (Dipodomys deserti), and Desert Banded Geckos (Coleonyx variegates variegates) during my nighttime forays. My favorite nighttime finds were a five foot Great Basin Gopher Snake (Pituophis catenifer deserticola) that I found crawling along a rocky hillside bordering our camp, and a Mojave Desert Sidewinder (Crotalus cerastes cerastes) crossing a dirt road.

During that project I learned a great deal about desert ecology and became familiar with tortoise behavior and an array of desert wildlife. I tracked adults and hatchling tortoises and witnessed them feeding, drinking rain, engaging in courtship, and breeding. Kit foxes (Vulpes macrotis), jackrabbits (Lepus spp), Burrowing Owls (Athene cunicularia), Cactus Wrens (Campylorhynchus brunneicapillus), Phainopepla (Phainopepla nitens), Southern Desert Horned Lizards (Phrynosoma platyrhinos calidiarum), Red Racers (Coluber flagellum piceus), and Northern Mojave Rattlesnakes (Crotalus scutulatus scutulatus)…these are just a sample of the fascinating wildlife I got to see on a regular basis. I saw evidence of mountain lion predation on desert tortoises, and I found a horned lizard skeleton skewered on a yucca by a Loggerhead Shrike. Plus I had a whole suite of desert plants to learn. The ecosystem was completely different from anything I was used to, and I wanted to learn as much as I could while I was there. However, my term was soon over, and I left feeling like there was so much I had yet to see. I wasn’t sure when, but I knew that one day I would return to the Mojave.

Banded Watersnake

Banded Watersnake

And I got that opportunity to return this May while visiting my girlfriend, Kelly Hunt. Kelly has lived in southern Nevada for several years now and has worked seasonally and been a long-term volunteer for the Nevada Department of Wildlife (NDOW). One of her main responsibilities over the years has been tracking Banded Gila Monsters (Heloderma suspectum cinctum) via radio telemetry for NDOW’s state herpetologist, Jason Jones. Gila Monsters are very poorly studied in Nevada, so Jason began this telemetry project back in 2013 to help gain a better understanding of their ecology in the state. Kelly introduced me to Jason, and he graciously invited me to do some volunteer work while I was out there, including tracking “monsters” (as they affectionately refer to them)! This had all the makings for a dream vacation!

The day following my arrival, Kelly and I packed up the telemetry gear and headed out to one of their Gila Monster sites. My excitement was building by the second. I knew that the days were getting hotter and that the chances of seeing a monster out during the day were decreasing, but I was still hopeful. We got an early start to try to beat the heat, and we hoped that our quarry would have the same strategy. We spoke to another volunteer who had regularly tracked the Gilas at this site, and he told us that just a few days prior, he had witnessed one digging up a tortoise nest and feeding on the eggs. This gave me hope that there were monsters on the surface. Kelly started out tracking the first one, and I followed about 5 meters to her left, scanning the terrain for any sign of large lizards. During the spring, Gila Monsters will come down out of the mountains into the bajadas and nearby lowlands in search of mates and foraging opportunities. Tracking Gila Monsters Although with summer fast approaching, the Gilas would soon return to their summer haunts high up the nearby rocky slopes. The signal from our first monster was strong and wasn’t coming from the direction of the mountains. As the beeps from his transmitter got louder, my excitement was getting harder to contain. I knew we were getting close. We scanned the terrain around us, looking for any movement or that distinct orange and black banding. And suddenly I saw just that. About 30 feet away sat a beautiful Gila Monster, resting in the shade of a large creosote. I pointed and exclaimed in a loud whisper, “There’s one!” I was overwhelmed with excitement. I felt my jaw drop almost to the dirt as I stared at the magnificent beast before me. It remained motionless, but alert with its head elevated. I was certain it was aware of our presence. I kept my distance and hurried through my backpack to retrieve my camera. As I began shooting, he slowly crawled up under the base of the creosote bush, seeking the security of the branches. I sat and watched him for a moment as Kelly recorded the necessary data. I didn’t want to leave. I could’ve sat there all day watching him, but we had more monsters to track, so we moved on.

It was my turn to track the next one, so I donned the receiver and Yagi antenna. The signal from this individual was much softer, indicating it was further away. We struck out in its direction, but still paying attention to the habitat we were passing. There were a handful of transmittered monsters in that area, and we knew that they too could be active. We also wanted to find new individuals that could be added to the study. We came to a large wash and series of large elongate rock formations. The signal was still a ways off, so I stuck to my course, while Kelly broke off to inspect some good looking habitat. Several hundred meters out, I began to ascend a gentle slope, riddled with large rocks. The signal was getting very strong, and I slowed my steps and scanned more meticulously. I walked around a large bush and glanced to my right, and there he is! This Gila was slowly lumbering down the rocky slope right towards me! Once again I felt my heart starting to pound. I froze, and he seemed completely unaware of my presence. He moved his head from side to side, flicked his large fleshy tongue every couple seconds to taste the substrate along his route. About 3 meters out, he seemed to notice my presence and altered his trajectory slightly, but overall seemed unconcerned. I paralleled him for a while taking a few photos until he stopped in the shade cast by a large Ephedra. We took data while he rested, and then watched as he decided to meander off in the direction of some large rocks. The encounter left me with a permanent smile. That morning was going to be rather hard to top! We spent the rest of the day looking for a Gila whose signal had recently gone missing, but all we found were Great Basin Whiptails (Aspidoscelis tigris tigris), Common Side-blotched Lizards (Uta stansburiana), and a single Mojave Desert Tortoise in the opening of his burrow.

Mojave Desert

That night we conducted our first road cruising survey of the week. NDOW has designated five different road cruising routes that pass through habitat with a significant elevation gradient. This allows for sampling across multiple habitat types and the potential to detect all local snake species. The goal of this study is to have people cruising multiple roads across the Mojave at the same time and compare species and activity between routes, elevations, and habitat types. They also have a solid 15-year data set for one of the routes that they want to keep building on.

We began according to protocol, 30 minutes after sunset, and immediately we were seeing reptile activity. Desert Banded Geckos and Desert Night Lizards (Xantusia vigilis) were everywhere. Even though the main focus of the survey was snakes, we still noted all of them. Our first snake was a dead on road (DOR) Desert Glossy Snake (Arizona elegans eburnata). Northern Desert NightsnakeIt was a real bummer, especially since I had never seen one before, but we made up for it minutes later by cruising a small Northern Mojave Rattlesnake. Over the next two hours we continued to cruise scores of geckos, and then we capped off the night with my lifer Northern Desert Nightsnake (Hypsiglena chlorophaea deserticola). These harmless rear-fanged colubrids had been a target of mine during my last visit to Nevada, so it was a good note to end on.

The following day, Kelly took me to a different Gila Monster site. Jason wanted us to find and collect a female Gila whose transmitter battery was due to die later in the year. He wanted to remove the transmitter before that happened. On the drive in I spotted two Long-nosed Snakes (Rhinochelius lecontei) on the road. Curiously, one was DOR and the other was alive and appeared to be inspecting its deceased counterpart. We escorted him off the road and collected the DOR for Jason. The terrain at this site was much rockier and steep and that not only made the hike more strenuous, but it could also bounce the transmitter’s signal, making an animal more difficult to track. However, Kelly’s expertise and knowledge of this female, coupled with her last known location and her vicinity to a favorite overwintering burrow, made locating the monster easy. Unfortunately, it was much hotter than the day before, so the monster was deep inside her refuge, and we could only take some data. But Kelly also found a nice gray phase Southwestern Speckled Rattlesnake (Crotalus pyrrhus) along the way! Only ever having previously glimpsed one deep inside a tortoise burrow, I was thrilled to see this snake on the surface. On the way back Kelly showed me some creosote flats where she has seen Northern Desert Iguanas (Dipsosaurus dorsalis dorsalis), Western Long-tailed Brush Lizards (Urosaurus graciosus graciosus), and Long-nosed Leopard Lizards (Gambelia wislezenii). With a lizard noose in hand, we walked the open sand, scanning the bases of the creosotes, and Kelly soon spotted several Desert Iguanas that ducked into Kangaroo Rat burrows. I finally got the search image down and spotted one that we were able to noose and inspect up close, before promptly returning it to the shade.

Southwestern Speckled Rattlesnake

That night we met up with Jason to cruise a different route. He had surveyed it the night before with some good luck. Most notable were some Variable Groundsnakes (Sonora semiannulata semiannulata), a “clarus” phase Long-nosed Snake, and a Sonoran Lyre Snake (Trimorphodon lambda). All of these were snakes I had hoped to see on this trip. This was also supposed Red Spotted Toad to be a good route for Spotted Leaf-nosed Snakes (Phyllorhynchus decurtatus) which neither Kelly nor I had seen before, so our anticipation was high. En route to the site, a large Southern Desert Horned Lizard scurried off the road in front of us, and we took that as a good sign. We started off on our first pass with a small Southwestern Speckled Rattlesnake. This was more of a red phase individual, and once again I turned into an ecstatic little kid at the sight. The variability in color displayed by this species is truly remarkable, ranging from blue-gray to red to almost pure white, and everything in between. It’s one of the reasons why this species is one of my all time favorites. In the following passes, we cruised three more speckled rattlesnakes, including one large individual who we cruised twice. After being coaxed off the road the first time, we found it on our next pass back stretched out along the white line, presumably soaking up heat from the asphalt. As a serious rattlesnake aficionado, I was in heaven. I was just as excited about the fourth one as I was the first. It would’ve never gotten old. Next, we came across a DOR Mojave Desert Sidewinder and an adorable Red-spotted Toad (Anaxyrus punctatus) which would be the only amphibian found that week. And then finally, we got one of our targets….a small, foot long snake lying motionless in the road. We jumped out of the car and ran over, unsure of its identity. We stooped to inspect it and simultaneously erupted into celebration. It was our lifer Spotted Leaf-nosed Snake! We thought it was a great note to end on, so we decided to finish our last pass and head back home. But luck was on our side and we cruised a second Spotted Leaf-nosed Snake! After a short photo session, we happily called it a night.

Spotted Leaf-nosed Snake Mojave Desert Sidewinder

For our next two days of fieldwork we decided to change it up a bit. We joined NDOW’s Joe Barnes to band some Peregrine Falcon chicks. Once again trying to beat the heat, our days started well before sunrise. The first day Joe took us by boat to a Peregrine Falcon eyrie on a plateau overlooking the shore of Lake Mead. We landed the boat and hiked up the plateau to the ledge just above the peregrine nest. From there, Joe rappelled down to the nest to collect the noisy little fuzz balls. The adult falcons scolded us the entire time and dove at Joe as he approached the nest.Measuring Peregrine Falcon chicks It was incredible seeing these raptors perform such high-velocity dives right in front of us. It really gave me a heightened appreciation for their hunting tactic of knocking unsuspecting birds right out of the sky. Once back on top, we assisted him in banding the chicks, taking measurements, and taking feather samples before he returned them to the nest. Joe collected the feather samples along with prey remains found in the nest, so he can test them for mercury and other contaminants that that may pose health risks to the falcons. Although I was looking for herps the entire time, we only saw a few black and white blurs of Western Zebra-tailed Lizards (Callisaurus draconoides rhodostictus) as they sped away from our path. The next day was very similar except the entire approach was on foot. After crossing about a mile of bajada we navigated a large wash and began ascending a steep mountain slope. It took us close to two hours to reach the eyrie, which was close to the mountain’s summit. I was really hoping to see a Panamint Rattlesnake (Crotalus stephensi) on this outing, but I had to settle for a fantastic view and the mummified remains of a Common Chuckwalla (Sauromalus ater).

Fortunately, I didn’t have to end on that note. I got to spend one more day doing Gila Monster telemetry and road cruising surveys before heading back home. All the monsters we tracked were underground that day, making me even more grateful for the two I had seen earlier in the week. I did, however, see a Great Basin Collard Lizard (Crotaphytus bicinctores) while searching for new monsters. We decided to return to the same route we had cruised two days prior in high hopes we would find a Sonoran Lyre Snake, however, it wasn’t meant to be. It was still far from a bad night, as we cruised another Common Nightsnake, a Long-nosed Snake, and two more Spotted Leaf-nosed Snakes. It was a great way to end my trip, and it leaves me a handful of target species for next time, as I already know I will be coming back. And just as exciting as experiencing Nevada’s wildlife was spending time with the biologists who work so hard to study and conserve them. I’d like to extend a huge thanks to Jason and Joe, who allowed me to tag along and hopefully make a small contribution to their work. For me, seeing their passion and getting to work alongside them, was just as exciting as seeing all those Speckled Rattlesnakes.