Parks After Dark

The sun had just started to dip behind desert mountains as the hikers began to arrive at Saguaro National Park’s Rincon Mountain District, a half hour east of downtown Tucson. The last rays of sunlight painted the sky a brilliant pink. These visitors came on this sweltering early October evening for a leisurely mile-and-a-half hike, but this walk had a twist: It would unfold entirely in darkness.

Dusk offered some respite from a record heat wave — for two weeks, high temperatures had not dropped below 100 degrees. Soon the stars were shining, and the unmistakable scents of the Sonoran Desert — the smoky-sweet resin of creosote, the mineral aroma emanating from the dry soil — filled the air.

[Summer 2025] Parks After Dark - Saguaro

In 2023, Saguaro National Park was certified by DarkSky International as a location that provides visitors an authentic nighttime experience even in the vicinity of artificial light.

©FRED ESPENAK

Our guide for the evening was Jeff Wallner, an interpretive ranger. A native of Wisconsin, Wallner had worked at Saguaro for over 30 years. He wore a wide-brimmed National Park Service hat and spoke in a folksy Midwestern drawl. Saguaro’s nighttime programs date back to the early ’90s. Since then, thousands of visitors have participated. Some activities are strenuous and involve climbing to the summits of rugged peaks. Others, like this one, consist of short, easy walks meant to educate visitors about the ecosystems of Saguaro and the nocturnal behaviors of the animals that inhabit this beautiful stretch of the Sonoran. Embracing night is also more of a necessity at Saguaro than in most other parks, since hiking in the blazing daytime temperatures of mid-summer and early fall can be dangerous, even deadly.

Before our group of a dozen or so plodded into the darkened desert, Wallner had us play a game. From a bag, he retrieved several large laminated cards and distributed them to the group. Each featured an image of an animal native to Saguaro — deer, fox, skunk, badger, mountain lion, javelina, among others. Once everyone had a card, Wallner recited short riddles. When we thought he was describing our animal, we would hold up our cards. As we learned, many creatures that call the park home can also be found in northern climes and are not physiologically suited to the desert. Instead, most have developed strategies to survive in this harsh environment. To endure the Sonoran’s brutal summer temperatures, they lie low during the day — in shaded enclaves and burrows — and emerge at dusk and at night.

“Things really pick up here after dark,” Wallner said.

Night is becoming an increasingly popular time to visit national parks. The Park Service does not keep statistics on nighttime visits — other than overnight stays — but Jeremy White, a physical scientist focused on preserving the parks’ night skies, said that in the course of his work he’s seen an increase in nighttime visitation in parks, often because of activities related to astrophotography, stargazing or the observation of natural phenomena such as meteor showers and aurora borealis. Park visits are on the rise overall, and at crowded national parks that limit daytime entries during the high season, some visitors without the required permits are getting in before sunrise or later in the evening. While the agency has no direct evidence that climate change is contributing to a modification in visitation patterns, White said, high temperatures are altering visitors’ schedules in some locations. “The parks, especially the desert parks, are definitely encouraging visitors to push their activities into the early morning or later into the evening,” he said. “The staffs know that that this means increased visitation at night.”

Schedules vary from one year to the next, but more than 100 national park sites have offered night programs. While many of these focus on astronomy, there is much more to do at night in the parks than marvel at stars overhead. At Voyageurs National Park in Minnesota, one of the nation’s darkest parks, the Park Service has operated nighttime boat tours on Namakan Lake, which straddles the U.S.-Canada border. At Bryce Canyon, White Sands and Canyonlands national parks, visitors can embark on guided nighttime walks. Darkness is only one part of the night experience. As the clamor of day fades, the rich soundscapes of the parks emerge — the crashing of ocean surf, the sluicing of mountain streams, the whistling of wind through stands of pines. And sometimes, at places like Saguaro, park-goers can contemplate — and even commune with — a menagerie of animals roaming the night.

Growing numbers of travelers are also exploring the parks at night on their own, White said. These self-guided visits often entail night photography or venturing into the backcountry with headlamps. My first experience in a national park at night was back in the 1990s on a hike to the summit of Longs Peak, in Rocky Mountain, which we began on a brisk August night in the light of a full moon.

Many parks are located far away from urban centers and have taken steps to mitigate light pollution. As a result, more than 40 national park sites are now certified as International Dark Sky Places by the group DarkSky International. Some of the darkest and remotest national parks, such as Death Valley and Big Bend, have become de facto stargazing meccas with night programs focused heavily on astronomy. Other dark sky parks, such as Chaco Culture National Historical Park in New Mexico, Glacier National Park in Montana and Great Basin National Park in Nevada, boast their own observatories. At Great Sand Dunes National Park and Preserve in Colorado, visitors have attended night photography sessions, learning techniques to photograph the Milky Way and other celestial objects. “Visitor interest in experiencing naturally dark night skies has definitely grown over the past 20 years,” said Karen Henker, a spokesperson at Arches and Canyonlands national parks. She said Arches has created an area exclusively for night sky viewing that includes benches for lying down and gazing up at the stars. Other parks in Utah, she said, use overlooks or campground amphitheaters to offer formal programs with telescopes. On clear nights, staff may rove the viewing areas with high-powered binoculars to help visitors take in the moon, planets and bright deep-space objects.

Activating this link will open a larger version of the image in the same window for a more detailed viewing.

Everglades National Park visitors spot an alligator during one of the park’s nighttime programs.

NPS/ANTHONY SLEIMAN

Activating this link will open a larger version of the image in the same window for a more detailed viewing.

Glacier National Park staff take advantage of the park’s dark night skies by offering star parties at Logan Pass.  

NPS/JACOB W. FRANK

As parks increase nighttime access, they are improving signage and disseminating relevant information, both online and at visitor centers, White said. “We want to make sure that our park visitors are safe,” he said. “That translates to providing good information, making sure people fully understand the risks and are prepared with their headlamps, extra layers and water.” It has also meant that parks have been doing everything from controlling parking and traffic flow to providing locations to set up cameras and telescopes. “We just want folks to understand that these are wild places still and to have that extra level of awareness,” he said.

After Wallner collected the animal cards, we got in our cars and convoyed from the visitor center to the Mica View Trailhead, a few miles into the park’s interior. As I rounded a corner, I caught a glimpse of a tarantula in my headlights. In the bright light, the spider looked like a furry hand ambling across the pavement. At the trailhead, Wallner summoned us to a picnic table where he handed out flashlights. He turned one on, and it emitted a red glow. The red light, he explained, provides illumination without deactivating the rod cells in our eyes, which are responsible for night vision. Later, Wallner said, he would distribute a different kind of flashlight that emits ultraviolet, or “black,” light. (Those are used for a special purpose, which he disclosed later.)

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Flashlights in hand, we set out. Dim red circles bounced along the trail. After a few minutes, Wallner pointed a bright flashlight into the night, illuminating a tall saguaro. Hundreds of saguaros surrounded us in this dense stand – one the park refers to as a “cactus forest” – but the flashlight beam focused our attention on this lone specimen, its arms cast upward against the backdrop of star-fringed mountains. Wallner turned off his flashlight, and the cactus vanished into the blackness.

We pressed farther into the backcountry, and the stars brightened. So, too, did the light dome of Tucson. Despite the glow, in 2023 Saguaro was certified as an Urban Night Sky Place by DarkSky International, a designation that recognizes places near cities that offer visitors an authentic nighttime experience even in the vicinity of artificial light. Park officials have taken steps to reduce ambient light from exterior fixtures at park buildings and in surrounding communities. “Saguaro does not have the darkest skies of any national park,” said Drew Reagan, communications manager at DarkSky International. “But it is a critical area of darkness in an area very close to a major urban center. It is a refuge for animals and people to escape the worst effects of urban light pollution.”

Indeed, national parks are among the last redoubts of darkness in a rapidly brightening world. In the U.S., 8 out of 10 people can no longer see the Milky Way from where they live. Even if the Park Service today works hard to protect darkness, that was not part of the agency’s original mandate, said astronomer Tyler Nordgren, who wrote “Stars Above, Earth Below: A Guide to Astronomy in the National Parks.” (Nordgren also popularized the phrase “Half the park is after dark.”) “By preserving large chunks of the landscape free from floodlights, streetlights and billboards, the Park Service, just by accident, was also preserving the dark skies above them,” he said.

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Saguaro’s night programs, like others across the country, are not merely aimed at connecting visitors with the night and the animals that dwell in it. They are also designed to educate visitors about the night skies that Indigenous people saw centuries ago, before sprawling cities filled the valleys and climbed the mountainsides. Jacelle Ramon-Sauberan, a member of the Tohono O’odham Nation, co-leads stargazing programs in Tucson and tours at nearby Kitt Peak National Observatory, teaching visitors about the culture and way of life of the “desert people” of the Sonoran. “We have a story that talks about how Coyote created the Milky Way,” Ramon-Sauberan told me. Another story, she said, tells of one of the Tribe’s staple foods, the white tepary bean, which the Tohono O’odham believe was gifted to them from the Milky Way. “To understand our past and to know where we came from, we have to be able to see the stars,” she said.

Spencer Burke, a ranger at Saguaro, said the night sky is critical to understanding the cultural meaning of some of the land features and sites that make up national parks, which were part of Tribal territories before being eventually annexed by the U.S. government. Prior to coming to Saguaro in 2023, Burke worked at Mesa Verde National Park, in southwestern Colorado. In his time there, he oversaw the park’s dark sky certification application, which was approved in 2021. At Mesa Verde, the U.S.’s first national park created explicitly to protect cultural resources, the night sky may have shaped the very design of the ancestral sites, including Sun Temple, that visitors come from across the world to see. The Ancestral Puebloans were highly attuned to the night sky and used the moon and constellations as a celestial calendar to help them determine when to plant and harvest.

“For most of our history as a species, we have been looking up at the same night sky,” Burke said. “Light pollution not only has a huge impact on species. It also affects our bodies and our psyche, because we’re missing out on this connection with the universe and that connection with the skies our ancestors saw.”

Back on the Mica View Trail, the group moved farther from the parking lot and into the night. We paused near a picnic bench, and Wallner retrieved a plastic bag and handed out small plastic vials, each containing a specific scent. Our task was to identify the smell and then find others in the group with the matching scent. This lesson, Wallner said, illustrates how bats use their keen sense of smell to find their young in colonies writhing with hundreds of babies. The aroma emanating from my vial was pleasing — a far cry from the musty ammonia smell of juvenile bats — and instantly recognizable as mint. Others had vanilla and lemon. In the darkness, our sense of smell was heightened, and we found our scent partners within seconds.

As we pretended to be bats, real ones flitted overhead, pinging out repetitive metallic chits. Among the multi-species swarm was the lesser long-nosed bat, one of the saguaro’s pollinators. The tiny winged mammals — only 2 to 3 inches in length — are drawn to the cactus’s pale, trumpet-shaped flowers, which open at night and are reported to have a perfume reminiscent of the smell of overripe melon. The bats don’t hold back, going in headfirst and coming out covered in pollen, which they unwittingly deliver to the next flower they plunge into. “Bats get a bad rap, but they are really one of the unsung heroes of this ecosystem,” Wallner said.

The next activity Wallner led required us to use our ears — and our voices. He used a small audio recorder to play the calls of the array of birds that swoop through Saguaro’s darkness. Then we broke into several groups with the task of learning one of the calls — the hoot hoot hoot of the great horned owl, the eerie shusssssh of the barn owl, or the poor-will of the appropriately named common poorwill. First, we vocalized our calls individually. Then, like a mad conductor, Wallner told us to deliver our calls all at once, our voices rising into the night in a deranged avian chorus.

On the trail, I spoke with Gina Mercer, a Phoenix resident visiting this side of Saguaro for the first time in years. “I’ve never been here in the dark,” she said. “It’s so cool.” Mercer was there with her daughter Maddie. One summer a few years ago, Maddie made the trek to the bottom of the Grand Canyon and back up, getting on the trail at 3 a.m. “The temperatures at the bottom were 115 in the daytime,” she said. “There is just no way you can hike in heat like that.”

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The longer she walked in the dark toward the bottom of one of the world’s deepest canyons, the better her eyesight got. In the darkness, Maddie spotted the largest scorpion she’d ever seen. (“It was a little bit scary,” she said.) She also found that darkness made the difficult trail seem less daunting “because we couldn’t see how far we had to go, especially on the way back up,” she said.

After about 45 minutes, we reached the turnaround point and began working our way back toward the trailhead. With adequately night-adapted eyes, some people in the group walked confidently without the aid of flashlights. It turns out that night hiking can be not only enjoyable but also liberating once you overcome fear and allow your eyes to drink in the darkness.

And yet night tourism brings its own set of risks and potential impacts. In addition to introducing potential safety hazards as people negotiate winding roads and rugged trails in the dark, increased nighttime visitation in the parks means more ambient light, from the headlights of cars to exterior lighting of park buildings. Which is to say, without careful management, night tourism can jeopardize the very resources the parks are meant to protect.

Research shows that visitor recreation taking place in wildlife habitat can disrupt animal behavior and movements substantially. A 2018 study published in Science by researchers at University of California, Berkeley, for example, found that animals worldwide have increasingly shifted their daytime schedules to accommodate ours. According to the report, “an animal that typically split its activity evenly between the day and night would increase its proportion of nocturnal activity to 68% of total activity near human disturbance.”

Even seemingly modest undertakings such as hiking and mountain biking can alter the way animals go about their business. Another study conducted near Boulder, Colorado, found that species sensitive to human disturbance such as black bears and coyotes shifted more of their activities to nighttime to avoid hikers, mountain bikers and horseback riders. The researchers also observed that some animals, such as bobcats and mountain lions, abandoned certain locations altogether if human activity became too intense. In other words, the ways visitors recreate in protected spaces can drive animals farther into the wilderness and deeper into the night. But how will animals adjust as people continue to encroach on their habitats during their few remaining hours free of human interference?

Nordgren, the dark sky enthusiast, said we must become more aware of our shadowed surroundings if we hope to be better stewards of the night and the animals that rely on it. “To do night tourism better, we’ve got to do it in a way that respects wildlife, that doesn’t impinge upon the sea turtles laying their eggs, or the birds that are hunting at night,” he said. “We have to take care to think about how we humans interact with and impact the natural world around us.” To that end, some national parks, including Joshua Tree and Yellowstone, have prohibited “spotlighting” wildlife with artificial light. Other parks such as Grand Teton National Park are using trail camera footage to reveal critical routes used by animals, often at night, and rely on that information to devise protections for those areas.

Though the main loop roads in Saguaro are closed to cars at night, bikes are not restricted, and all trails remain open to foot traffic after dark. With climate change bearing down on the Sonoran and projected to increase average temperatures in the Southwest by up to 8.5 degrees Fahrenheit by the end of the century, nighttime visitation could spike in the years ahead. Nonetheless, Burke said that with proper training, people can recreate responsibly at night in Saguaro and other parks. “We need to let people know that they have a much better chance of seeing animals and not disturbing them if you keep quiet and use the red-light feature on your flashlight,” he said. “We can balance the needs of visitors with the needs of nocturnal animals.”

At our final stop, Wallner handed out the UV flashlights that he had promised earlier — it was time for the night’s grand finale. The UV light, for reasons not fully understood, causes scorpions to fluoresce. “Shine the light along the edges of the trail, and you might get lucky and find a scorpion,” Wallner said.

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With that we headed off, probing the darkness with our ultraviolet wands. The scorpion hunting, however, proved tricky. Pieces of bark and plant material as well as certain rocks glowed under the black light, producing false positives. But within a few minutes, an excited call came from up the trail.

“Found one!” exclaimed a young woman, her teeth glowing in the stray beam of a black light like the grin of the Cheshire Cat.

There, no larger than a dime, amid a scattering of sticks and dried mesquite leaves, was a bark scorpion. It sat motionless, glowing green. It almost appeared painted onto the desert floor. The group gathered around to look at the tiny arachnid.

“Amazing,” said Gina Mercer. “I live here, and I’ve never seen one. I wonder how many of these guys I’ve stepped right over in the middle of the night.”