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The Heliograph: Summer 2025

heliograph.

The Heliograph is the Sonoran Desert Network and Desert Research Learning Center newsletter.

The Sonoran Desert Inventory and Monitoring Network collects long-term inventory and monitoring data on natural resources in 11 national parks in the Sonoran Desert for the purpose of helping parks manage natural resources. The Desert Research Learning Center, in Tucson, Arizona, supports network operations and offers outdoor education opportunities to local student groups.

What is a heliograph?

Recent Reports & Where to Find Them

To see these and other reports, go to the Reports & Publications page on our website.

A close-up shot of biocrust and seedlings on the ground surface. The biocrust looks like black and brown scaly patches atop brown dirt, and the seedlings are bright green sprouts.
Biocrusts at the Desert Research Learning Center.

NPS/C. MCINTYRE

New Biocrust Study

In January 2025, Sonoran Desert Network researchers Kara Raymond and Cheryl McIntyre started collecting data in a new study of potential interactions between biocrusts and herbicides. The goal of the study is to determine if herbicides and how they are applied impact biological soil crusts, or "biocrusts."

Biocrusts are living communities of lichen, fungi, moss, and cyanobacteria that grow on the soil surface in the Sonoran Desert and other dryland regions. These living communities support the growth of Sonoran Desert landscapes by performing very important ecosystem functions. Their tiny root-like filaments help prevent soil erosion and increase the amount of nutrients in the soil, like nitrogen, phosphorus, and organic matter that plants need. They also prevent moisture from seeping underground too quickly.

Herbicides are frequently used to remove invasive plant species, like buffelgrass, red brome, and stinknet that threaten Sonoran Desert ecosystems. Raymond and McIntyre are testing what happens to biocrusts when sprayed with three different pre-emergent herbicides: aminopyralid, indaziflam, and pendimenthalin. The first season of data collection is complete and samples are currently being analyzed by Dr. Arnold’s lab at the University of Arizona. Data collection will resume again next winter. We hope information from this study will help us keep biocrust communities safe as we manage for invasive plants.

International Volunteers

One of our favorite traditions has been welcoming International Volunteers in Parks (IVIPs) to Tucson for internships of 11–52 weeks. We were recently joined by two international volunteers:

A group photo of a large group of Sonoran Desert Network workers, all lined up around Reagan, an international volunteer. They stand in front of a mural.
A group photo at Reagan Masud's going-away party at the Desert Research Learning Center. (Reagan is in the center in a brown t-shirt and baseball cap.)

NPS/S. STUDD

Reagan Masud from Ghana

Reagan started his IVIP program at Saguaro National Park with the Interpretation rangers in November 2024. He helped staff the visitor centers at the park and manned a public outreach table at La Fiesta De Tumacácori at Tumacácori National Historical Park. He worked with the Sonoran Desert Network for the second part of his internship, starting off with a National Outdoor Leadership School (NOLS) Wilderness Advanced First Aid course. His internship transitioned to focus on Sonoran Desert Network wildlife monitoring. He prepared wildlife gear, tested the equipment for the season, and deployed cameras at Saguaro National Park West with our field crew. He shared interesting reflections on the comparison of park wildlife management in the United States and Ghana. Having returned home, Reagan is resuming his PhD in the Department of Wildlife and Range Management at Kwame Nkrumah University of Science and Technology!

Three people with backpacks standing on a dirt path in the desert, smiling for a photo. Two of the people are holding either side of a wildlife camera.
Stijn Buuron led camera deployment and retrieval for his project in Saguaro National Park. (Stijn is on the right, holding a wildlife camera.)

NPS/J. MCGEVERLY

Stijn Buuron from the Netherlands

Stijn started his program in early February 2025 and immediately set up his project studying the impact of (human) trail traffic on wildlife in the area. He deployed and retrieved wildlife cameras at systematically chosen locations near trails in Saguaro National Park, Tucson Mountain District with our crews. He then collected vegetation data near the cameras with the help of network botanists. He analyzed the photos and vegetation data, wrote a report, and presented his findings. He also helped us deploy and retrieve our cameras at Organ Pipe Cactus National Monument for annual wildlife monitoring. He enjoyed learning about how the United States performs wildlife monitoring and management.

We have now had IVIPs from Australia, Denmark, England, France, Germany, Ghana, the Netherlands, Scotland, and Slovakia. We have also had remote IVIPs from China and South America. Read more about our volunteers on our Interns & Volunteers webpage.

Monitoring Updates

A field technician leans over near two spikey plants and yellow flowering plants in the desert with a tape measure to collect vegetation data.
Upland vegetation monitoring in Chiricahua National Monument in 2024.

NPS/E. SCHNAUBELT

Vegetation and Soils

Uplands vegetation

Our uplands vegetation crew monitored 63 plots across five park units during fall 2024. Nearly every Sonoran Desert Network field staff member and technicians from the Chihuahuan Desert and Northern Colorado Plateau networks collected data in our upland plots. This March, we completed early detection invasive plant surveys at Tumacácori National Historical Park and mapped a suite of exotic plants to help park staff focus their management efforts. Next up in fall 2025, our crew will monitor upland plots in Chiricahua National Monument, Coronado National Memorial, Saguaro National Park, Montezuma Castle National Monument, and Organ Pipe National Monument.

Riparian vegetation

In April 2025, our vegetation crew completed the third season of riparian vegetation sampling at Tumacácori National Historical Park along the Santa Cruz River. We surveyed obligate wetland plants, inventoried tree density, and mapped the length of the river as it runs through the park to track changes in stream health over time. Our crew became more familiar with plants they don’t often see, and frequent gray hawk and Wilson’s warbler sightings were a highlight of the trip.

Two field technicians, one standing and one crouched down on a sandy beach reaching into water, collect water from a large, black, reflective pool of water under a giant rock overhang.
Two field technicians collect water to run chemical analyses for a spring in Saguaro National Park.

NPS/E. SCHNAUBELT

Seeps, Springs, and Tinajas

In 2024, the Sonoran Desert Network springs crew successfully completed annual monitoring at 34 springs/tinajas across Saguaro National Park, Chiricahua National Monument, Coronado National Memorial, Fort Bowie National Historic Site, Gila Cliff Dwellings National Monument, Montezuma Castle National Monument, Organ Pipe Cactus National Monument, Tonto National Monument, and Tuzigoot National Monument. We were able to sample at all sites except one; it was a backcountry site in Saguaro National Park East that our crew couldn't reach because water sources were unreliable for backpacking in the area. We are currently drafting web reports with the 2024 results.

There was very little and in some cases no water at many springs sampled in 2024, similar to 2023. The lack of water in these two years is unusual for Sonoran Desert springs based on data we collected in prior years (see our previous springs monitoring reports).

Starting in 2024, we deployed autonomous recording units (ARUs) at most springs and along certain streams to monitor for amphibians and other wildlife that utilize these vital water sources. We will analyze the acoustic data from the ARUs to identify species of interest that may be present, such as native Chiricahua and lowland leopard frogs (Rana chiricahuensis and Rana yavapaiensis, respectively) or invasive American bullfrogs (Rana catesbeiana). Environmental DNA was also collected at springs and streams as a secondary way to detect these hard to see species.

Two field technicians inspect plants along a measuring tape in a dry flood plain covered in short and tall dried up, brown plants with green cottonwoods looming overhead.
Monitoring riparian vegetation at Tumacácori National Historical Park.

NPS/E. SCHNAUBELT

Streams

Although most elements of streams monitoring are on pause as we complete a review of the protocol, we continued aquatic macroinvertebrate and environmental DNA (eDNA) sampling at Gila Cliff Dwellings, Montezuma Castle, and Tuzigoot national monuments and Tumacácori National Historical Park. Field crews also completed the third round of riparian vegetation sampling at Tumacácori National Historical Park.

Two people wearing neon vests crouch in a desert of cactus and small shrubs to set up a wildlife camera on a stake facing a field of saguaro cacti. The desert valley is lined with rugged mountains in the distance.
Setting up cameras in Organ Pipe Cactus National Monument in 2024.

NPS/J. MCGEVERLY

Wildlife

In June, our wildlife team finished collecting wildlife photos in three Sonoran Desert Network parks. In the winter, crews deployed cameras in Saguaro National Park (Tucson Mountain District) and retrieved them after about five weeks. We repeated this process at Organ Pipe Cactus National Monument in the spring and at Chiricahua National Monument in early summer. In total, we deployed 162 cameras this season. Right now, our data managers are cleaning and finalizing eight seasons of data for Organ Pipe Cactus and Chiricahua national monuments. We will publish the Saguaro National Park wildlife results very soon.

Community engagement in wildlife monitoring this season was integral to our success. Our two international volunteers, Reagan Masud and Stijn Buuron, joined us at different points in the season. We are also working with the Tohono O’odham Nation to help train their AI models to identify animals in wildlife photos because the nation is working on its own camera study to help better understand wildlife in the region. Lastly, 20 community scientists joined us to deploy and retrieve cameras this year from Saguaro National Park.

For more information and recent reports please visit the Sonoran Desert Network website or check out our photo gallery.

2025 Data Collection

Click on the calendar below to find out where and when we will be collecting data for the remainder of 2025.

Staff Updates

Introducing...drumroll...some additions and changes to our team!

A shield-shaped logo. The top edge is shaped like mountain peaks with snow details, a green silhouette of trees stripes across the middle, with a blue river flowing across under them. Text reads: Scientists in Parks, National Park Service.

Thank You to Scientists in Parks Interns

For the last year, the Sonoran Desert Network team included four recent graduates passionate about natural resource protection. Check out our new Scientists in Parks article about how they helped our inventory and monitoring efforts and the great contributions they made with their independent projects. Thank you, Justin Sontag, Naomi Friedman, Annika Munson, and Bryn Callie!

Partnership with Southwest Networks

The Sonoran Desert Network collaborates closely with the Southern Plains Network (based in Pecos, NM) and the Chihuahuan Desert Network (based in Las Cruces, NM). Together, our three networks form the Southwest Network Collaboration. Our partnership, the first of its kind in the Inventory & Monitoring Division, stands upon pillars of efficiency and sustainability. Due to similarities between monitoring protocols, we plan network operations around sharing gear and staff.

In addition to field support, the Southwest Network Collaboration encourages frequent sharing of ideas and expertise in scientific monitoring and data management and analysis. This improves data quality and monitoring results in all three networks. In celebration of this excellent partnership, enjoy these photos from a few of the 2024 “crossover episodes,” trips with staff from multiple networks:

Four photos: two people sitting on the ground examining soil stability tests; four people pause their hike to marvel at the mountains; a selfie while canoeing; and a group of scientists eating at a picnic table at a food shop.
From left to right: Southwest Network Collaboration staff examine study soil stability at the Desert Research Learning Center; marvel at the view while hiking in the Rincon Mountains; take a selfie on the Rio Grande in Big Bend National Park; and have a team dinner while working at Tuzigoot National Monument.

NPS/E. SCHNAUBELT

Two people shoot rifles at targets about 20 meters away. The targets are printed images of bullfrogs and this figure shows closeups of the targets with bullet holes in them.
To learn about bullfrog control techniques, our crew attended a USGS non-law enforcement firearms training to learn safe gun handling practices.

NPS/E. SCHNUABELT

Native Species Reintroduction Project

In 2023, the Sonoran Desert Network began a project to support the recovery of native amphibians and garter snakes in eight Southwest parks. The first stage of this project involves inventory and subsequent control of invasive American bullfrog populations (the foremost predator of native amphibians and garter snakes in the Sonoran Desert). Within the first months of the project, we collected eDNA in park wetlands to detect the occurrence of American bullfrogs and the diseases they carry, as well as the presence of rare native aquatic animals. Initial eDNA results indicate current bullfrog infestations at Gila Cliff Dwellings, Montezuma Castle, and Tuzigoot national monuments. Early detection monitoring will continue across all Sonoran Desert parks. Unfortunately, the inventory also suggests that many once common native aquatic animals appear to have reduced ranges or are locally extirpated. With park staff as well as state, federal, and non-profit partners, we are developing bullfrog control strategies for both existing, established infestations, and to rapidly respond to new bullfrog incursions identified through ongoing early detection monitoring.

Fortunately, our initial three years of inventory work indicate that some historical bullfrog infestations have been naturally extirpated—perhaps a silver lining to the intensive regional drought of the 2010s. For sites with appropriate habitat, this would permit parks to move directly into native aquatic animal recovery efforts, with continued bullfrog early detection-rapid response operations to protect these vulnerable new native populations. Other sites will require sustained bullfrog removal before reintroduction of native species. This year, we've joined forces with state game and fish departments, academic partners, non-profit conservation groups, and our sister land management agencies to develop bullfrog early detection and control strategies. Next steps include meeting with other DOI bureaus to plan native aquatic animal reintroduction. These actions will help restore native species populations, rejuvenating wetland and riparian ecosystems.

Community Connections

Connecting with local communities and parks is a highlight of the work we do at the Sonoran Desert Network. This year, we hosted booths at the Tucson Festival of Books and Fiesta de Tumacácori, chatted with visitors at Reid Park Zoo, and presented at the Casa Grande Ruins Annual Speaker Series. Showing up to speak with the public provides opportunities for exchanging Sonoran Desert knowledge and experiences. We look forward to more outreach events later in 2025.

Three images: three children and an adult standing at a table staffed by a scientist at a festival; four Sonoran Desert Network staff standing behind a table filled with education materials; and a biologist giving a slide presentation.
From left to right: the Sonoran Desert Network at the Tucson Festival of Books; our scientists at Reid Park Zoo Lights; and a network wildlife biologist giving a presentation at Casa Grande Ruins National Monument.

NPS

At the Desert Research Learning Center

Aside from being a productive workspace, the learning center is also a place to host workshops, trainings, tours, community science events, and programs throughout the year. We are grateful for our relationships with all the organizations that have shared this space with us and look forward to working with them and others in the future.

Recent events at the Desert Research Learning Center:

  • National Outdoor Leadership School (NOLS) taught a Wilderness Advanced First Aid course. Members of the Sonoran Desert and Chihuahuan Desert networks refreshed their first aid knowledge and gained new skills to be prepared for the field.

  • Arizona Conservation Corps Trails Crew completed maintenance on the learning center grounds, including clearing vegetation and updating our trail.

  • Saguaro Interpretation staff held environmental education programs, such as Pollination Investigation, Junior Ranger Camp, Saguaroology, Art in the Park, and Hiking Club.

  • Multiple crew trainings took place for the protocols we use to monitor natural resources, including upland vegetation and amphibians, in our parks. These trainings took place in our main program room and on the learning center grounds.

  • We welcomed new officemates—the more, the merrier! The Desert Research Learning Center is home to a growing list of groups in addition to the Sonoran Desert Network team, including the NPS Southwest Invasive Plant Management Team; the NPS Southern Arizona Office; NPS Intermountain, Pacific, and Alaska regions; NPS Northeast Region Office of Tribal Relations; NPS Seeds of Success program; US Fish and Wildlife Service; and our partners from Tucson Bird Alliance, Conservation Legacy, and Northern Rockies Conservation Cooperative.

  • SIP interns, Naomi and Annika, painted a beautiful mural on the DRLC wall above the sustainable foods garden.

  • Tony and Janet Schall, volunteers extraordinaire, completed many learning center projects. During their latest stay with us, they helped renovate our apartments with new sound-proofing installments, helped with our septic system rebuild, worked on the trail, planted and harvested vegetables in our sustainable foods garden, maintained the stream, and helped keep the building clean and in good repair.
A yellow-pink sunrise glows in the sky behind blue mountains, desert plants, and a traditional wood ramada at the Desert Research Learning Center.
One of the Desert Research Learning Center's ramadas at sunset.

NPS/E. SCHNAUBELT

Campground Name Reveal

With the help of Sonoran Desert Network staff, volunteers, and local Scouting America members, the DRLC's campground and guest bathroom are officially on the market…well, for reservations, that is. We offer it as a place to stay for multi-day NPS meetings and events, visiting scientists, and volunteer learning center work groups, and it has already proved useful on many occasions. Implementing the design was the focus of an Eagle Scout project that brought together about 70 scouts and their families, led by our long-time superstar volunteers Tony and Janet Schall.

After days of discussion on a community white board, we officially announce the new name as: “T&J Schall Campground,” in honor of Tony and Janet. Not only did they play a critical role in building the campground, but their contributions have also been invaluable to the development and maintenance of the Desert Research Learning Center itself. They have dedicated about six months every year for nearly nine years to maintaining the Sonoran Desert Network facility and beautifying the grounds. They are vital and cherished members of our team, and their names belong in Sonoran Desert Network history!

Map of the T&J Schall Campground. There are 14 walk-in tent pads of various sizes, and a picnic area in the center. The map shows the campground path and a trail that goes by the campground.
Map of the T&J Schall Campground at the Desert Research Learning Center.

NPS

Past Heliographs

Visit our Heliograph webpage to read previous editions.

Tags

Casa Grande Ruins National Monument, Chiricahua National Monument, Coronado National Memorial, Fort Bowie National Historic Site, Gila Cliff Dwellings National Monument, Montezuma Castle National Monument, Organ Pipe Cactus National Monument, Saguaro National Park, Tonto National Monument, Tumacácori National Historical Park, Tuzigoot National Monument more »

Last updated: August 27, 2025