Field Work
Bleak, barren, desolate. Infernally hot. These are the words that come to mind when most people think of the dunes of Death Valley or Devil’s Playground; the home of the Mojave fringe-toed lizard. Yet to me, the Mojave Desert is not a wasteland, but a beautiful and mysterious wonderland.
The first time I visited the Mojave Desert, I was an undergrad at UC Santa Cruz. I went on a herpetology field trip led by Shawn Kuchta and Mitch Mulks in May of 2006. That was the first time I saw a wild fringe-toed lizard skitter across the dunes, and the first time I used a fishing pole noose to catch lizards. I was hooked.
I fell in love with the Mojave Desert - its peaceful solitude and wide open spaces; the dry, clean air, the stunning sunrises and sunsets; the fascinating plants, wildlife, and catastrophic geology. Most of all, I was enthralled by the reptiles, and I became ever more curious as to how they evolved with the natural rhythms of the unforgiving landscape.
Therefore it wasn’t surprising that I decided to pursue a master's project on Mojave Fringe-toed Lizards. I thought it would be relatively easy to go down there, noose a bunch of lizards, get all the DNA samples I could possibly need (at least 100) and go home. Not to mention, I’d have a blast doing it, and I should have plenty of time to go road cruising for snakes at night. I figured I should be able to catch 10 lizards a day, at least. But just in case, I’d allow myself at least two months in the desert, April and May.
Boy, was I in for a surprise!
The first time I went to Ibex Dunes at Death Valley, reality set in. As the morning sun lit up the mountainside in brilliant red, I could see why the Paiute called this place Tomesha, the Land A'Fire. I also understood why George Lucas decided to film Tatooine somewhere around here. I hiked 10 miles round trip in my jeans and T-shirt. I also forgot my sunglasses and sunscreen. I got sunburned, yet I caught zero fringe-toed lizards. I only saw one. I daydreamed about waterfalls. I began to have some doubts.
The whole month of April, I never caught more than 6 lizards in a day. That was my best day, in Pinto Basin, Joshua Tree National Park. My field colleague, U.S. Army Wildlife Biologist Cameron Rognan, was with me that day, and he caught four out of the six lizards.
Most days that month, I was lucky to catch one or two. At times, the northwest winds would blow over forty miles an hour. In the mountains, we’d get occasional gusts over eighty. At times like that, the lizards were smarter than I was, and would simply hunker down under the sand, while I tried to remove the sand grains from my eyes. I went up to a week without catching a single lizard.
Even on the good days, when the lizards were out and about, I had a lot of learning to do. As Dr. Bill Presch would later tell me, these aren’t side-blotched lizards! They certainly aren’t easy to catch, at least not until you begin to understand the life history of these lizards.
Mojave fringe-toed lizards live in a harsh environment. Sand dunes offer very little concealment or protection from loggerhead shrikes, American kestrels, prairie falcons, red-tailed hawks, roadrunners, burrowing owls, sidewinders, glossy snakes, coachwhips, badgers, coyotes, kit foxes, leopard lizards, and off-road vehicles. Not to mention, it rains very rarely, sometimes not for years at a time. Summer highs can top 120 degrees, and winter nights can drop below freezing. And when the wind really picks up, the dunes are transformed into sheets of flying sand.
So how do fringe-toed lizards survive? To avoid predators, they have to be very vigilant. When they bury in the sand, with just their eyes poking out like little “sand crocodiles,” they are virtually impossible to see. Even when they are perched out in the open, they blend in so well, that they are nearly impossible to see until they move first.
And when they do move, they really move. With their fringed toes, they can race across the dunes with ease. Typically one just sees a yellow shape rocketing like a little drag racer, leaving a little spray of sand. They zig-zag for 10-20 meters behind a creosote bush or burroweed and disappear.
I would poke around behind the bush, trying to figure out where it went, but usually it buried under the bush, or shot down a rodent burrow, and I was out of luck. Thus, even though I saw a lot of lizards at first, I caught few of them.
I also learned that fringe-toed lizards, like other desert animals, have highly variable reproductive success from year to year. The previous year (2007), there was a record drought, and virtually no baby fringe-toed lizards (or any baby lizards) survived in southern California. Therefore, I only encountered adult fringe-toed lizards during my field season. Population densities were unusually low.
Fortunately, I learned a few tricks from my old professor, Barry Sinervo, and Mitch. Using a seven foot lizard noose, I had much greater success than the five foot noose I was using earlier. I learned to patiently stalk lizards from a great distance. I learned to recognize ideal habitat, and approach carefully so not to disturb the lizards. By moving in ultra-slow motion, I could gradually stalk up close enough to noose the lizard.
The closer I stalked, the more tense I became. The critical moment was slipping the noose over the lizard’s neck. At this point, if I became nervous and jittery, the noose could slap the lizard’s face and spook it to run away. This happened to me occasionally and it was always frustrating.
But if I was careful, and I moved extra slowly at the most critical moment, even though I wanted to move quickly and get it over with, I’d succeed.
Teamwork made things easier. Cameron and I often had to work together to noose lizards that were sheltered under dense burroweed. They are much easier to catch under creosote. It was extra tricky to maneuver a noose through dense brush without snagging it on a branch or spooking the lizard. The trick was patience; I eventually learned that once a lizard thinks it’s hidden, it will just stay still until you go away or spook it. So as long as we take our time, and read the body language which warns us that it was about to spook, we could usually noose a lizard taking refuge under a bush. Often times, I would spend 15 or 20 minutes stalking one lizard, only to have it rocket away down a burrow at the critical moment. But as I practiced, I became more and more successful.
Finally I learned the art of the “magic trick” – digging a fringe-toed lizard out of the sand with my bare hands. To do this, I began to learn the art and science of tracking. I changed my strategy; rather than simply stomping through the dunes, scanning for lizards that I flushed out, I began to move carefully, reading the signs in the sand.
The spring weather typically alternates between a few hot days, a few windy days, and a few beautiful days. After a few days of wind, the confusing maze of tracks is swept clean; and it is on those mornings that it is easiest to track the lizards.
The trick is to wake up early; one key mistake I made was over-sleeping. The lizards like to bask in the sunshine when the sand surface temperature reaches 90 degrees F, but they are more elusive once the sand reaches 120.
So on those early mornings, armed with my infrared temperature gun, I found the tracks where a lizard emerged from the sand. I would quietly stalk along the tracks, and I learned to recognized the bump of sand where they bury underneath. I would then sweep the sand away and grab the lizard.
I must credit Dr. Bill Presch and especially his graduate student, Jeff Jarvis, for demonstrating the magic trick to me. I learned that fringe-toed lizards rarely move more than a few inches once buried in the sands. In fact, research shows they almost never go deeper than four inches or so.
In the end, I was lucky to work in amazing places, including Death Valley, the Mojave National Preserve, Fort Irwin National Training Center, Joshua Tree National Park, and Arizona. I was equally lucky to meet many other great scientists and students who share my love for the desert.
I caught about 25 lizards in April and the beginning of May, and 100 lizards at the end of May and the beginning of June. In that sense, I succeeded in my goals; I obtained enough DNA samples for my research.
I learned many things from the desert, but most of all I learned the value of patience.
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