Boosting Bats by Restoring Mexico's Agaves

By Kristen Pope and Laurel Neme

The endangered Mexican long-nosed bat (Leptonycteris nivalis) hovered beside the 20-foot-tall stalk of an agave and probed the deep flowers with its long snout. Lapping at the nectar, flakes of pollen blanketed its muzzle, ready to drop into the next flower.

With light-colored flowers and nighttime blooms, agaves are specially adapted for bat pollination. However, these agave plants can take seven, eight, or even 10 years to bloom, so finding the right flower to forage is a waiting game.

Agaves are considered chiropterophilic, or “bat-loving,” plants, and BCI is working with a number of partners to restore agaves and help nectar bats in the U.S. and Mexico. So far, the team, which includes Borderlands Restoration Network, Colectivo Sonora Silvestre, and Especies, Sociedad y Hábitat A.C. (ESHAC), has planted over 9,500 agaves, begun restoration work on over 200 hectares, signed eight conservation agreements, and taught environmental awareness workshops to hundreds of school children and community members. This work is crucial because bats and agaves depend on one another.

“Many species in this botanical group have evolved, developing a series of adaptations so that bats become their main pollinators. In this way, agaves offer food and, in return, bats contribute to the pollination of these plants,” says Dr. José Juan Flores-Maldonado, executive director of the Mexican nonprofit ESHAC.

Over 75% of the 211 known agave species are endemic to Mexico, meaning they are found only there. In northeastern Mexico, four different bat species use agaves for food, including the Mexican long-nosed bat (Leptonycteris nivalis), Lesser long-nosed bat (Leptonycteris yerbabuenae), Mexican long-tongued bat (Choeronycteris mexicana), and occasionally the Pallid bat (Antrozous pallidus). Mexican long-nosed bats’ 750-mile migration from central Mexico to the southwestern United States is based on the seasonal shifts of agave blooms.

Bats carry pollen long distances and can cross-pollinate distant groups of agaves. This helps the genetic diversity of agaves, increasing their resilience to disease, and mitigating the detrimental impact of climate change, which is threatening to shrink their range by 70–95%.

 

Agaves and bats under pressure

Climate change, habitat transformation, and human use threaten bats and agaves in the region. Flores-Maldonado points to a study conducted from 2009 to 2018 in Cumbres de Monterrey National Park in Mexico which found a considerable amount of habitat loss, including 4.8% of primary forest vegetation and 8.9% of scrub communities. He says these land changes are due to forest fires, agricultural and grazing practices, urban development, and climate change.

While agaves perform vital ecosystem functions like stabilizing the soil, preventing erosion, and providing habitat and food for wildlife, agave is also a very important plant for humans. In northeastern Mexico, residents plant agaves on communal farming land allotments called ejidos and use these plants to make alcohol, food, fences, and other items. However, agaves are typically harvested by humans before they send up their flowering stalk, leaving no flowers or nectar for bats. Their sugar content is highest just before the stalk goes up, making the agaves appealing for a variety of uses.

Flores-Maldonado says the quiote, or floral stalk, can also be eaten as a treat. He says it is cut just before a flower is produced—when sugar concentrations are highest—and grilled. The versatile plant’s leaves can also be used as feed for livestock during times of drought, when other forage isn’t available. Agaves are also famously used to produce liquors like tequila, mezcal, and bacanora.

Bacanora, which is derived from agave, is mezcal made in Sonora, Mexico. It was illegal to produce until 1992, and before its legalization, people would harvest wild agaves to make bootleg liquor.

Lea Ibarra is co-director of Colectivo Sonora Silvestre, a Sonora-based nonprofit partnering with BCI on the agave project.

“People were making bacanora for so many years illegally, they would go to wild agave populations and harvest them,” she says. “It takes them seven to 10 years to flower, so populations were very damaged because of this practice, and it was illegal here in Sonora.”

She says bacanora is an important part of the local culture and regional identity, and now that it is legal, people are eager to help with agave planting projects to produce sustainable versions of the liquor.

“We wanted to get the people in the communities involved in the project,” she says. “Everyone loves bacanora here, and it is a very cool way to get people engaged with it.”

 

Planting agave to save bats

The symbiotic relationship between bats and agave prompted BCI to launch its agave planting initiative in the U.S. southwest and Mexico starting in 2017. During its initial phase, BCI worked with partners to bolster wild agave populations in key areas near Lesser long-nosed bat maternity roosts and migratory pathways.

“Protecting roosts is always the number one conservation action,” says Dan Taylor, BCI’s senior restoration specialist. “We’re going above and beyond that by protecting and restoring their foraging habitat.”

In 2019, BCI expanded the project and turned its attention to the “nectar corridor” used by endangered Mexican long-nosed bats. To identify potential target areas, BCI worked with ESHAC and local communities. Together, the team zeroed in on a 31-mile buffer zone near two caves, which are two of four known maternity roosts. Females give birth to one pup a year and need large energy reserves to raise their young, which is why restoring foraging sources near maternity roosts helps the growth and stability of the species as a whole. Yet the benefits go far beyond helping one endangered bat species.

“What we found with this project is much larger,” says Kevin Pierson, BCI’s chief conservation officer. “This bat and agave relationship holds keys to the resiliency of this ecosystem.” And a resilient ecosystem will prove vital for bats, agaves, and their human neighbors.

 

Growing the littlest agaves

Arizona nursery raises plants for restoration efforts

Since agaves take five to 10 years to reach maturity—and then the plant dies after it produces its prominent floral stalk—restoration efforts are crucial. Francesca Claverie is the native plant program manager for Borderlands Restoration Network in Patagonia, Arizona. Her organization works to raise a nursery full of agaves that will one day be planted in the wild.

Claverie’s team collects agave seeds from high-elevation mountain ranges after the agaves are pollinated. “Our team goes out in the mountains, lays big tarps down, and shakes

the seeds down, then we take them all back to the seed lab,” she says.

Her team records information about where they collected the seeds, including GPS coordinates, elevation, and other information. Then, they clean out the chaff and dirt so the seeds can be stored for years in the climate-controlled facility. Claverie says a single agave can produce thousands of seeds, which they will propagate and work with partners to plant in the wild.

Borderlands Restoration Network will also collect unwanted agaves from people’s properties. When people want to clear fire breaks or otherwise landscape their property, they will call the organization, which will go retrieve the plants.

Additionally, the organization works with citizen scientist volunteers to collect data about agaves using the National Phenology Network’s Nature’s Notebook app, which has a special campaign for the U.S.–Mexico borderlands, where people can track agave flowering. Climate change means agaves may flower earlier or later than in the past, which is a problem when bats time their migratory route by the blooms. Researchers will use this data to learn more about agave blooming, and how this will impact species such as bats and other pollinators.

 

Working together for conservation

Mexican collective works to protect bats and agaves

What started as a student conservation effort has now blossomed to an even bigger effort to protect bats and agaves. A group of students from two Mexican universities, the University of Sonora and the Technological University of Cananea, originally formed the Colectivo Sonora Silvestre collective to conserve the Sonoran ecosystem by working on a variety of projects related to bat pollination, agave restoration, wildlife monitoring, monarch butterfly assessments, and other projects. These dedicated conservationists—now university graduates—have expanded their efforts, forming the nonprofit organization Centro de Colaboración para la Ciencia y Cultura S.C. to continue their work.

In 2019, the group began working with BCI to plant 1,000 agaves and establish a nursery for native plants. They also focused on education by hosting lectures, workshops, and presentations, and recruiting community volunteers, including students, groups, and families, to help with the planting efforts. They brought 15 students to an all-day workshop held on a bacanora ranch where they learned all about production, including both the older harvesting practices and the more modern, bat-friendly ones.

“Most people didn’t know about the relationship agave has with bats, so they were very surprised to know about it,” says collective co-director Lea Ibarra. She says people would enthusiastically talk about seeing bats near bacanora ranches and be excited to learn about the connection between bacanora and bats.

When it was time to select agave planting sites, they chose locations within 50 km of caves where bats are known to live. They also selected sites with ranchers who were committed to helping the bats. Ranchers who participated signed commitment letters agreeing to regularly water the plants and allow all the agaves in the conservation gardens to bloom. In the future, the ranchers will let 2% of the agaves bloom (while harvesting the rest), so they can continue to feed the bats.

Some of the agaves are also planted near town entrances and main roads to increase awareness. On one hot day, the group went to water the agaves near their homes in Hermosillo, Sonora, and when they arrived at the site, they were thrilled to find other community members already there watering the agaves. This type of community partnership, with dedicated volunteers, is a good thing for bats, agaves, and humans alike.