Women return to tracking bighorn in the Mojave

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The Women in Science Discovering Our Mojave internship has provided new insights into the movement of bighorn sheep in the Mojave Desert, with game cameras collecting data and images of the elusive species. The internship expands this fall with three new interns further tracking bighorn movement and gathering data on the tamarisk beetle.

Interns (from left) Roseanna, Brandee, and Miranda. Please note that we followed all state social distancing guidelines.

Hi, Mary Cook-Rhyne here. I am the Education Coordinator at the Mojave Desert Land Trust and the program manager for the Women in Science Discovering Our Mojave (WISDOM) program. Last fall, MDLT and the Bureau of Land Management piloted the WISDOM internship program, monitoring bighorn sheep in Mojave Trails National Monument. It provided important data on their movements in the Afton Canyon Natural Area. This year, a new team of interns is continuing to monitor the movement of sheep in Afton Canyon, as well as launching a quantitative survey of tamarisk beetle populations.

According to 2019 reports from the US Bureau of Labor Statistics, women comprise only 28.8% of the workforce employed in the scientific fields, although they make up 57.1% of the total workforce. WISDOM aims to help engage women in STEM (science, technology, engineering, and mathematics) by providing a platform to gain knowledge and conduct scientific research, both in the field and in the office. This internship will increase their understanding of environmental science and land management issues in the Mojave Desert, and provide women with opportunities to conduct that research.

The next step

I’m excited to introduce you to our dedicated interns who are determined to further their understanding of conservation science in the Mojave.

Miranda is a Plant Science major in her senior year at Cal Poly Pomona. She also is minoring in Botany and Regenerative Studies. She is a lifetime resident of the Mojave and aspires to conduct graduate research on plant communities and desert ecology.

Roseanna graduated in 2018 from the University of California Riverside, earning her Bachelor of Science degree in Environmental Science in Statistics, Biology, and General Chemistry. She was born and raised in Twentynine Palms and loves to hike on public lands including Mojave Trails National Monument.

Brandee is from San Bernardino and now resides in Hesperia. She is in her senior year at California State University, San Bernardino majoring in Geography and minoring in Environmental Studies.

A first trip into the desert

On our first field day, Roseanna and I left Joshua Tree at five in the morning to beat the heat, driving separate off-road vehicles to observe COVID-19 social distancing guidelines. We met up with the other interns at the Barstow BLM Field Office, where we each introduced ourselves, went over itinerary paperwork, and handed out field gear before heading out to Afton Canyon.

Afton Canyon, the “Grand Canyon of the Mojave”. Photo by Michael Mora/MDLT

For the Bighorn Sheep Monitoring Project, we use high quality field cameras to collect data from seven locations around this stunning canyon, which locals call the “Grand Canyon of the Mojave Desert”. When we arrived in the canyon we started working right away, hiking to the seven trail cameras and “shaking the trees” (more about that later). Each intern has their own task associated with retrieving and logging data from the cameras. At our third camera location I was pulling gear out of the vehicle when Miranda said, “Mary, look!”

Even though I grew up in the Mojave, I have rarely seen a bighorn. I looked to where Miranda was pointing and there were two sheep standing by a watering hole, a big ram and an adult female or ewe. Then we heard a scuffling noise, turned, and on the other side of the train tracks there were two juvenile bighorns. They were running around playing, like my own kids do when we go camping.

Two juveniles playing, just like most kids I know. Note how well they blend in with the terrain, this is why we didn’t see them at first. Photo: Mary Cook-Rhyne/MDLT

Desert Bighorn (Ovis canadensis nelsoni) are a protected species. They migrate during the different seasons, accessing areas that have food, water, and shelter. They tend to hide up on the hills and mesa tops and it was great to be able to see them down in the canyon. What a great way to start this internship!

A herd of seven bighorn sheep caught on camera in one of the finger canyons.

Tracking the tamarisk beetle

We changed the batteries and SD card from cameras and then chose a tamarisk tree nearby to conduct the quantitative study of tamarisk beetles, which have become established along the canyon’s river corridor. Tamarisk trees (Tamarix spp.) are a non-native species that were introduced to the U.S. in the mid-1800s; they were originally planted as an erosional control method and later as an ornamental tree. Tamarisk diminish water supply by establishing deep taproots that leave less surface water for other plant species. Plus, once the leaves fall, they create an overly saline undergrowth which alters the soil, creating a harsh habitat that native plant species find difficult to grow in.

We choose trees near our cameras to help streamline field work. Using a bug net, we conduct five sweeps of the tree branches to create a data set. Then the number of adult and larval beetles are counted, along with any other insects found in the net. Tamarisk beetles (Diorhabda spp.) were introduced as a biocontrol method by the USDA in the 1960s. The beetles only eat the tamarisk, causing trees to die slowly as they can no longer go through the photosynthesis process. This usually takes between 3–5 years and has helped cut down on the amount of herbicides and pesticides sprayed. But the beetles are a management concern here because they migrated to the canyon and they create fire hazards because of the dead trees.

By the time we finished work in the eastern portion of the canyon and headed to the campground, we found ourselves alone. It was too hot (102 degrees) by lunchtime to see animals or people near the campground. All the surface water near the first train overpass has dried up for the summer as well. Though, Brandee pointed out that a bunch of turkey vultures were soaring high overhead. Good thing we brought extra water…

As we walked the finger canyons, gathering data and finishing fieldwork, I began to realize something profound: this canyon has been used for millennia by humans, flora, and fauna. It’s strange to look around and think about the people who have come before. We are separated in time, but not place. However, the canyon walls must have seen so many changes after being formed by the draining of the Pleistocene Lake Manix.

We are currently preparing for our next field day. MDLT will keep you updated as these two projects progress. Also be on the lookout for stories written by the interns themselves! This fall a different set of interns will begin to study the dark sky quality within the western half of Mojave Trails National Monument.

This internship program is made possible through funding from Southern California Edison International.

Wildlife cameras pinpoint movement of protected bighorn sheep