A group of teenage scouts and their parents hiked down the Arizona trail in the waning light, just as the sun was setting on a 108-degree day. My husband Catlow and I were leading the Saturday night adventure, expecting to hike a couple miles until the trail intersected with Rincon Creek. We had intel that there might be fireflies in this location, so our plan was to camp out in the creek for a few hours to see if these rare beetles were actually there.
We were one of 11 groups and over 100 people venturing into Tucson’s creeks at night for I Spy Fireflies, the first annual firefly community count in the Tucson basin. The anticipation was high, no one knowing quite what to expect, but each group hoping they would be the ones to spot fireflies.
Just a few months before, I had been chatting with nature photographer Julius Schlosburg, with whom I work to photograph our creeks, rivers, and the wonders we find there. For a couple years, Julius has been sharing with me his love for fireflies, which are very rare in Arizona. While I grew up seeing fireflies in NH, I had never seen them in the desert, and I had never even considered they might be in the Santa Cruz Watershed.
As Julius and I talked, a lightbulb went off, and I blurted out to Julius, “What if we do a community science survey for fireflies this summer in all of Tucson’s rivers?” Julius loved the idea, and so did our River Run Network team, so we were off to the races.
One of the things I love about my job is bringing people out to our creeks, especially when there is flowing water. As we entered Rincon Creek from the AZ trail, we walked through a dry river bed but noticed some muddy patches from rain a few nights before. We were less likely to see fireflies if the creek hadn’t been flowing, but we still held out hope.
In some ways, fireflies remind me of beavers. Most people don’t know beavers or fireflies are here in Southern Arizona and that they both used to be abundant. Both invoke our imagination and wonder and draw us out to observe and explore.
Picture This
Close your eyes and picture the Santa Cruz River 200 years ago, before beavers were hunted and extirpated, and before major groundwater pumping began. Imagine a series of connected wetlands shaped by beaver families, with cool water shaded by towering Fremont cottonwoods, Goodding’s willows, and Velvet mesquite trees. Lush elderberries, ashes, vines, and seep willows created a dense understory that engulfed the river.
Interestingly, we saw some of those same trees out along Rincon Creek, though they were spotty and limited to right in the creek bed. I walked around our camp and found Goodding’s willow, Arizona ash, and one baby cottonwood.
For our survey, we were filling out a data sheet, provided by the Xerces Society, to describe the habitat we were in. What was the vegetation like? Was there light pollution? And finally, if we were lucky enough to see fireflies, what color were the flashes, and what was the flash pattern?
Southern Arizona is a priority location for the Xerces Society to look for fireflies, with so little remaining habitat and several threatened populations. Julius connected us to Saff Killingsworth, Endangered Species Conservation Biologist with the Xerces Society, based in AZ. Saff and another Xerces Firefly Lead biologist, Candace Fallon, met with us to plan the survey and adapt their methodology for our community count. Saff was also able to join a field training with our survey leaders, teaching us about firefly biology, habitat, and identification.
Xerces Society currently has a petition out to list the Southwest spring firefly as an endangered species, and the Southwest synchronous firefly is also a species of concern. Through their Firefly Atlas project, they are working with community scientists to document specific species of fireflies: both where they are found and where they are absent. Species-specific data points that note presence or absence are important for understanding more about imperiled populations and informing conservation efforts.
A Spontaneous Idea Sparks a Community Science Discovery
It turns out our idea to do a firefly community count was not only fun, but useful science! Science that is carefully coordinated by the staff on our River Run Network team, notably Lauren Knight and Nadira Mitchell, who adapted well-tested strategies from our annual beaver count for the firefly survey. Thanks to our partnership with the Xerces Society and stellar organizing by Watershed staff, our spontaneous survey idea transformed into a massive coordinated volunteer event in just a few months.
During our survey lead training, we experienced what Saff called hallucinating fireflies. As Saff had warned us, when you’re eager to see fireflies, our eyes start to play tricks on you, and you start seeing little flashes. Was that a firefly up in the trees, or was that a star twinkling? If the group starts “hallucinating” together, you might be seeing some actual fireflies. And when you finally do see them up close, you know it’s the real deal, especially when the flash pattern happens as the beetle flies close by!
Out in Rincon creek, a few of us definitely hallucinated fireflies. And yet those illusive, far-away light flickers never got brighter or closer, so we had to agree we hadn’t conclusively seen fireflies.
Our cell phones were stashed away in our bags, to make sure no one was scaring away the fireflies or ruining our night vision by looking at a bright screen. When we got back to our vehicles after 10 pm, texts came rushing in. We were the last ones to report for the night. I texted: “Rincon Creek is back out. No confirmed sightings.”
The texts from everyone else were a jumble, but a few messages stood out:
Esther/Tesha: “We got one at Wentworth on Tanque Verde Wash!”
Julius: “We got firefly! They’re at Cienega Creek.”
Lizbeth: “We saw a lot of them and none were flashing.”
Angel: “Cienega Creek is out and done with lots of sightings! Julius is still in the creek naturally, but the rest of the group is officially out ( : Great night, y'all!”
Esther/Tesha: “There were tons at Tanque Verde Wash on Wentworth.”
Within this barrage of messages, it was hard to follow exactly who saw what, but yes, it was becoming clear–there were fireflies spotted in Tanque Verde Creek and Cienega Creek! In three different locations!
Fireflies were seen in the Tanque Verde Creek, in the exact location where Watershed and our River Run Network volunteers have been working to restore the flows and the forest for the last decade.
Over the last five years, our volunteers have removed invasive Arundo from 75 acres of the creek, in an area we fondly call the Tanque Verde Bosque. For a decade, we have engaged with local landowners on conservation and restoration projects, and for seven years, we have monitored the flows in Tanque Verde Creek. We also host our annual celebration, Flow and Feast, at this location with the sole goal of showing our love and appreciation for the creek.
I had to go out and see it with my own eyes, so the next Saturday night, we headed out there on a family excursion. We spotted the flashes pretty immediately at sunset. While we didn’t see as many fireflies in the survey location, we did hike about a half mile downstream, and we spotted fireflies essentially throughout that whole stretch of forest.
I checked with Saff, and she confirmed that Xerces didn’t have any records of fireflies in the Tanque Verde creek west of Wentworth Rd. We at Watershed had never seen or heard of them there either, even though our staff and volunteers go there on a weekly basis.
The Magic of the Bosque
It’s fitting because the bosque has always been a magical place for me. So much so that at last year’s Tanque Verde Flow and Feast, I dressed up as a fairy to greet people in the enchanted elderberry forest. This year, I dressed up again as the fairy queen, and led a sacred ceremony with hundreds of people as we embodied baby cottonwood, willow, and elderberry seeds growing up to be riparian trees, expanding the forest.
I’m in awe of finding this rare species in the creek, but finding fireflies in the Bosque is no coincidence. We have been loving the creek, at this location, for a decade—observing, restoring, and bringing healing energy and joy to this space.
I’m still a novice when it comes to fireflies, but I do know that they come out in the summer with the monsoon rains. They are out for a short window of time, perhaps a month or so if the conditions are right. Fireflies need damp soil for their larval phase, so that is why they are found along our rivers and in wetlands, though usually only in areas with year-round water or shallow-groundwater areas.
As we work towards our 50-year vision of restoring our heritage wetlands and river forests, we support a growing group of critters that call these places home. From fish to frogs, beavers to fireflies, and a rich diversity of plants, our rivers are sacred spaces. And our discovery of fireflies comes at an important moment, when our elected leaders and water managers are making decisions and plans for our water future. We have new large water users interested in moving into our watershed, potentially pumping groundwater and diverting recycled water in a time of extreme drought and new, permanent cuts in Colorado River allocations.
Fireflies are here, in Tucson’s creeks, and they’re sharing with us an important message. It’s time for us to really tune in, observe these magical creatures, and reflect on what they’re presence tells us about our rivers, our watershed, and how to protect this emerging resilience.