In a Mexican scrubland desert, a small bat flies by night, journeying hundreds of miles, pausing briefly to feast on the pollen of a singular flower: the wild agave plant. Agave plants bloom only once in their lifetime—taking 10 or even 20 years to do so. And the Mexican long-nosed bat (Leptonycteris nivalis) depends on these rare blooms exclusively for food as it travels from breeding grounds to birthing grounds and back again. In return, the bat pollinates the plants, laying a pathway forward for the next generation of this nectar highway.
The bat and its increasingly scarce agave flowers have danced in a delicate and intimate partnership for millennia. But they have been falling out of step as populations of both have taken a nosedive over recent decades. The partnership, however, is vital not just to their own survival, but also to the larger ecology of the region and to the people who make their lives on this land.
Small ranching communities, known as ejidos, dot the remote, dusty landscape. Years of drought and desertification have made an often tough existence there even tougher; some of the ejidos have been abandoned in recent years. But the bats and agave might bring salvation. With help from big-thinking bat conservationists, the solution could also benefit the soil, local ranchers and farmers, and the ecosystem as a whole.
The Mexican long-nosed bat lives mainly in desert-scrub woodlands and migrates along a 700-mile stretch from central Mexico up to southwestern Texas and the very bottom edge of New Mexico. It has ash-colored fur, a 14-inch wingspan, a leaf-like nose flap protruding skyward from its snout, and a narrow tongue that can extend out 3 inches—about as long as its entire body—to extract nectar from the agave plants, its sole food source during parts of the year.
Mexican long-nosed bats mate in the spring, and the pregnant females head north, surfing a wave of agave blooms up through northeastern Mexico. Along the way, they stay in caves or abandoned mines for days or weeks, until finally reaching their maternity roosts on either side of the border. There, these endurance-athlete moms give birth to one baby each, and those little bats must stay in their caves for six weeks before they can fly. In late summer, the moms and their young make the journey in reverse, feeding on species of late-blooming agave.
Agave plants bloom only once in their lifetime—taking 10 or even 20 years to do so.
There are more than 200 species of agaves, including dozens native to northern Mexico. These spiky succulents grow a giant stalk that towers as high as 20 feet, depending on the species, and then erupts in a feast of nectar-laden flowers. Afterward, they die. Their dried-up stalks remain for a time, like ghost trees rising from the scrub.
Agaves are keystone plants, crucial not just for bats but for a whole host of species. Hummingbirds also drink their nectar and pollinate them. Woodpeckers roost in the stalks and will also drink the nectar. Rattlesnakes make their home in the bases. “Crows, ravens, ringtail cats, foxes, deer,” said Kristen Lear, an American bat biologist and agave restoration program manager for Bat Conservation International, rattling off a list of species that use agaves. “Tons of animals. Agaves are just super important.” And like other native plants, they hold water that keeps the ecosystem more lush; they also help reduce soil erosion and store more carbon dioxide than most other plants.
Agaves were once plentiful across the bats’ entire migration route. But now, the bats are finding fewer and fewer of the flowering succulents to fuel their journey. There are a number of reasons for the agaves’ decline. Urbanization and development, along with agriculture and livestock grazing, have destroyed large swaths of habitat, leaving less and less undisturbed desert scrubland. A prolonged drought has made agave survival and regeneration more difficult in the areas that remain. Global warming has left this region, like so many others around the world, hotter and drier. When excessive heat and low rainfall reduce the amount of grasses available for cows and goats to eat, the hungry animals turn to other plants, including agaves. They will eat the leaves and the stalks, which are sugary and rich in energy. Ranchers sometimes cut the stalks down at the base just as they are flowering and leave them in the field for their herds. This deals a double blow: no nectar for bats and no pollinated seeds to grow into new agaves.
All of this causes a larger ecological feedback loop. The destruction of landscapes once filled with native plants leads to further desertification; when people clear the land for farming, or allow livestock to overgraze it, the entire system gets drier. The many gold, silver, and copper mines scattered throughout the area further dehydrate the system by sucking up groundwater, making it more difficult for agaves and other plants to grow. In parallel, Mexican long-nosed bat numbers have continued to decline, leaving fewer pollinators to keep the remaining agave populations going.
Bats in general are struggling, all over the world. About a quarter of all bat species are either endangered or threatened, and in the United States more than half of all bat species are “at risk of severe population decline in the next 15 years,” according to Bat Conservation International (BCI). “That’s a lot of species that are under threat,” says Lear. A combination of habitat loss, climate change, and the deadly “white nose syndrome” fungal infection have thrown many populations into a downward spiral.
The Mexican long-nosed bats, as well as their cousins the lesser long-nosed bats, which also migrate through the region, evolved with a pathway of blooming agaves. (Lesser long-nosed bats, whose populations have recovered in recent years, also feed mainly on agave nectar for most of their journey—along a more westerly path—but at the northern end of their route they eat nectar from large flowering cacti, such as saguaro. This varied diet has likely helped their recovery.)
Just like guests at roadside hotels on asphalt highways, nectar-feeding bats also need warm, safe places to sleep. In the 1990s, there were roughly 30 known roosting caves for Mexican long-nosed bats, each containing thousands of individuals. But over the past 25 years, many of the original caves that once sheltered the bats have become inaccessible or inhospitable to them. “They’re empty of bats,” said Ana Ibarra, a Mexican bat biologist and strategic advisor for endangered species for BCI. “They have been built over, they have been closed off, they have been used as dumpsters.” Today just 10 of the roosting sites remain, and scientists fear there are only between 6,000 and 10,000 of the bats left.
Agave, to many people, means not bats but alcohol: tequila and mezcal, agave-based spirits whose sales have increased nearly three-fold over the past two decades in the U.S. But while it might seem that growing agaves for these products would help the bats, the opposite has proved true. Producers often clear native plants to put in a monoculture crop that fails to provide the diversity necessary to sustain thriving communities of wildlife. Then, they typically harvest the agaves before the plants have a chance to flower—which leaves nothing for nectar-feeding bats to eat.
Some smaller producers, mainly of mezcal, allow a portion of the plants to flower. But most don’t. A Bat Friendly tequila and mezcal label had aimed to certify farms that let at least 5 percent of their crop flower, but only two brands were using the label as of 2021, the last year listed on the group’s website. Consumers, Ibarra pointed out, could demand change. “People that think they are totally removed from the game,” she said. “They’re not removed from this. There’s responsible consumption.”
The pregnant bats head north, surfing a wave of agave blooms up through northeastern Mexico.
In the meantime, to help save the nectar-feeding bats, BCI is working to replant and conserve agaves all along the bat migration corridors, and to safeguard the animals’ roosting sites. This means partnering with the ejidatarios, the farming and ranching families living in the ejidos, to restore degraded lands, harvest seeds, grow new agaves, and monitor bats. “The idea is that if we can restore the soil, water, native grass, that will create healthy habitat for these agaves to flourish,” said Lear. All of that helps the ejidos, too. “By restoring the habitat for the bats, we also restore the land for the people,” Lear said. Humans and nature can’t exist in isolation from each other; nature and culture are inextricably connected.
The Mexican long-nosed bats had made their late-summer journey south by the time I flew south to Mexico and headed for Matehuala, the small city in San Luis Potosí that’s the closest town to many of the ejidos working to protect the bats. The mother and baby bats had by this time reunited with the males in caves near Mexico City, about 400 miles south, where they would spend the winter. Ibarra, Lear, and I spent the night in Matehuala, and in the morning, we picked up provisions at the local Walmart and set out for the desert with a team from Comisión Nacional de Áreas Naturales Protegidas, the federal government agency that oversees Mexico’s protected areas. In the remote mountains near the border between San Luis Potosí and the neighboring state of Zacatecas lies a small conservation area called Mojonera, which is made up of land owned by seven ejidos. Mojonera and the ejidos together occupy a landscape of agave habitat that is vital to the survival of nectar-feeding bats.
Despite sharing the same general landscape, there were distinct differences from one ejido to the next. Variations in rainfall patterns as well as in historic land use made for noticeable shifts in the quality of the soil, the feel of the air, and the health of the agaves that the ejidatarios were planting, backed by funding from BCI. At Coyotillos, an ejido located in Zacatecas state, José Inocencio Moreno Mendoza took us to the field where he had planted rows and rows of agaves he and his wife had germinated from seed in the nursery. They were experimenting with a non-native agave species that was fast-growing and might flower in fewer than 10 years. There were also rows of prickly pear cacti, or nopal, which are harvested as a crop, and some native plants like mesquite and a kind of small, green pumpkin that’s used to make soap. But the field was dry and dusty, and many of the agaves looked like they were barely hanging on, leaves brown and shriveled. Still, Lear was confident they would survive. They were adapted to the desert, after all.
“This used to be a farm field, but when the rain stopped coming, nothing could grow,” said Lisette Leyequien, who oversees Mojonera, as she walked the rows. She hoped the agave might help keep the field from turning to desert—which would also help Mendoza and his family continue to grow crops and make a living on the land. “If the agave can’t even grow, corn can’t grow. Then the soil erodes,” she said. The soil was so compacted in places that it could no longer hold water even when the rains did come. It simply washed away.
Ranchers sometimes cut the agave stalks down and leave them in the field for their herds to eat.
The sun was blazing down. The air, like the soil, felt desiccated. We crossed a line of shrubby mesquite to another field, where the soil was darker and not as dry. Here, many of the agaves looked healthy and thriving—they were half a foot taller than the other ones, with strong green leaves poking skyward. Some infinitesimal difference from one field to the next—in rainfall, slope, perhaps past practices—seemed to have made a difference.
In each ejido that was helping restore the agave corridor, BCI was also working with the communities to diversify their farming practices and even their livelihoods to create a more sustainable landscape economically as well as ecologically. Down a dusty road, residents of Cuatro Milpas (“four cornfields”) had germinated hundreds of agaves, and these were thriving in a nursery. There, money from the agave effort had gone toward a small portable mill that enabled the ranchers to grind up invasive Russian thistle—tumbleweed—into cattle feed, providing an additional source of food that could help take some of the pressure off of the native agave plants. The ranchers also used the mill to grind up agave leaves into a watery pulp, which they mixed with molasses and fed to the cattle as well. Now the agave was benefitting the ejidatarios as well as the bats.
Harvesting the outer leaves of the agave does not harm the plant; in fact, it can stimulate the plant to produce “pups,” clonal babies that emerge from tendrils and will grow into new agaves. This is one of two ways that agaves reproduce, but because it creates a genetically identical plant, it doesn’t preserve the genetic diversity necessary for the species’ survival. For that, it needs to reproduce via pollinated seeds, which is where the bats and other pollinators are essential.
Watching the ejidatarios grind weeds into cattle fodder under the bright desert sun, it was easy to forget all about the bats. We were hundreds of miles from the small winged mammals, which would at that moment have been sleeping the day away in a warm cave near the capital. But the bat biologists grinned as tumbleweed dust filled the air. Their project was materializing before their eyes. “As biologists, we learn about so many things,” Ibarra said. “I’m learning about livestock food!”
Lear nodded. “Who knew bat biologists would be learning to feed cattle?” They were rebuilding a chain of survival for the migratory bats, using spiky desert succulents and bonds between people. “Bats are migrating such long distances, across boundaries, bringing people together,” Lear said. “I always think about the social connectivity. They connect actors across that corridor.” But because agaves take so many years to flower, the work Lear oversees is not just about bat-plant and bat-people connections. It’s also about “connecting timescales,” as she put it—planning for agaves, bats, and people to coexist into the future. 
Adapted from Roam: The Race to Knit the Natural World Back Together, to be published by Patagonia Books in 2025.
Lead image: Danita Delimont / Shutterstock
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Hillary Rosner
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Hillary Rosner is an award-winning science journalist and assistant director of the Center for Environmental Journalism at the University of Colorado Boulder. Her stories about the natural world have appeared in The New York Times, National Geographic, The Atlantic, and dozens of other publications.
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