In the dusty expanse of the Chihuahuan Desert in central Mexico, cold, dark caves hide among the brown rocks. Inside, in late spring, thousands of small hairy bats gather. Most of them are female and pregnant, and have undertaken a 1,609 km journey from southern Mexico to the southwestern United States to give birth.
They are hungry and fly for hours at night to find enough food. They fly from plant to plant, collecting nectar and spreading pollen as they go.
Among her favorites are the fluffy yellow flowers of the agave plant, flowers that only appear once in the decades of the plant’s life. These agave plants, with fleshy, prickly leaves, have a long history in Mexican culture. They are used to make syrup, ropes and soap, and their juice is the main ingredient in one of Mexico’s most emblematic products: tequila.
But wild agave plants are declining: in a study of 168 species, 42 are now threatened or seriously endangered. This means less food for the bats that depend on its flowers, and fewer bats means, in turn, that fewer agave plants are pollinated.
To break the cycle, conservationists are working with locals to plant thousands of agave plants, helping to feed bats and protect the future of tequila production in Mexico.
A species of bat dependent on agave, the lesser agave bat, has experienced a notable recovery in its population in recent decades, multiplying from 1,000 individuals in 1988 to an incredible 200,000 today. However, other species do not fare as well.
The long-tailed bat has decreased by approximately 50% in the last 2 decades and is currently in danger of extinction.
The biologist Marco Antonio Reyes Guerra is part of the Project Bat Friendly from the National Autonomous University of Mexico (UNAM), which collaborates with farmers to promote the cultivation of agave that favors bats. He explains that many of the threats bats face are caused by humans.
“If they suffer any disturbance in the caves, they will abandon them and lose their home. And people are deforesting several areas of dry forest, and in that forest there are species that bats use as a food source.”
Among these species are agaves, as well as other plants that bats feed on.
interdependence
Bat Conservation International (BCI) scientists are determined to turn things around for these declining species. The Agave Restoration Initiative consists of planting and protecting wild agaves in the “nectar corridor” that bats follow in their migration.
“All this was set in motion because, once these migratory species leave central Mexico, they depend largely on agaves,” says Ana Ibarra, a biologist specializing in bats and regional director of BCI.
Wild agaves face their own threats: they are harvested for alcoholic beverages, grazed by livestock, losing their habitat to agriculture, and facing drier conditions due to climate change; Additionally, since there are fewer bats, plants are pollinated less frequently.
Agaves depend on bats for reproduction, just as hungry bats depend on agaves for food.
“Bats and agaves have coevolved for several million years,” says Reyes Guerra. With their long tongue and long snout, bats can reach the narrow conical flowers of the agave to feed and collect pollen on their face and fur. “If bats are not present in an ecosystem, agaves likely will not produce seeds to reproduce, since agaves only reproduce once in their life.”
Without any intervention, and in the face of climate change, scientists estimate that threatened bat species will have 75% less access to agave nectar in 2050 than today.
For conservation efforts to work, agaves must be given the opportunity to grow large enough to flower, not only for the bats’ sake, but for their own as well.
Farmers growing agave for tequila often cut the stem to prevent flowering, resulting in a larger “heart” (or piña) for the harvest.
Instead of reproducing through pollination, these plants produce “saplings” that are genetic clones of the mother plant. This reduces the genetic diversity of the species, making it less resistant to the drier conditions that accompany climate change, as well as pathogens and pests.
“It is a significant risk for the agave and mezcal industry,” says Reyes Guerra. Ultimately, to survive as a species, agaves need pollination.
“Without bats, tequila and mezcal would not even exist,” adds Reyes Guerra. “If people want to continue drinking tequila and mezcal, they have to take bats into account, they have to worry about their conservation.”
Teamwork
Since the Agave Restoration Initiative was launched in 2018, the team and local communities have planted more than 180,000 native agave plants and have more than 150,000 growing from seed in nurseries in Texas, Arizona, New Mexico and throughout Mexico.
Reyes Guerra’s bat-friendly tequila and mezcal project is also working to increase the number of yellow agave flowers in southwestern Mexico.
Participating farmers allow at least 5% of their agave plants to mature and flower, so passing bats can feed. The alcoholic beverages produced by that farm are considered “bat-friendly,” and so far, 300,000 bottles of “bat-friendly” tequila and mezcal have been produced.
It’s not just farmers who are determining the future of bats and agaves. In Mexico, 53% of the land is community property, meaning that any conservation effort must involve everyone who lives on it.
“From the beginning, it was very clear that we needed to work with the communities and try to meet the needs of both bats and people,” Ibarra says.
The first step was to teach people that nectar-feeding bats are not harmful. People often think they are vampire bats, which can transmit rabies. According to Ibarra, some locals burn caves with bats “without knowing if they are really vampire bats.”
Lissette Leyequien is the director of the Sierra La Mojonera Flora and Fauna Protection Area, a natural space protected by the federal government in Mexico that collaborates with the Agave Restoration Initiative. Work closely with locals to change people’s perception of bats.
“In the past, people hated bats and tried to kill everyone they saw,” he says. But today, thanks to the educational program provided by BCI, people actively protect the caves.
“They don’t allow anyone to come in and do anything that could harm the bats. Almost all the people really love bats. They realize that the bat is a great provider of many benefits,” Leyequien says.
Six important roosts of wild bats are now actively protected by local communities across Mexico, and the initiative’s educational program has reached more than 1.5 million people.
Reyes Guerra agrees that bat conservation starts with locals.
“Conservation cannot be done without taking into account the local population and without consulting them to make decisions, because sometimes they have very valuable information that we, as scientists, are unaware of,” explains Reyes Guerra, who was recently guided to a small, difficult-to-access cave that housed five species of bats. “It is something really very rare to find,” he points out.
However, the real impact of recent conservation efforts will not be felt for a few years, as agaves need time to grow. But thanks to BCI and the Project Bat Friendlypeople are letting more agave plants mature and flower.
“You can see patches of flowering agaves in areas where nothing was seen before, because now people leave the flowering stems for the bats,” says Ibarra.
He adds that he has already detected an increase in the number of baby bats: “These increases are not large jumps, but they are constant. When a constant decline has been observed, simply keeping the numbers stable is a great victory.”
Leyequien has observed that, in places where agaves have been planted, the landscape is starting to look a little greener. “You can see a lot more fauna because they have food and places to hide.”
There is still time for an abundant, blooming corridor of agave nectar to form. But even then, Reyes Guerra points out that the bats will need more help.
“The problem with reforesting only with agaves is that bats feed on several species. Therefore, if we only plant agaves to feed the bats, it will not be enough.” Other important species are ceiba trees, ipomoea trees and cacti such as saguaros.
Restoring the agave population is just the first step in creating a healthy ecosystem where more plants and more bats can thrive. People are a crucial part of this ecosystem, Leyequien says, and they benefit when bats are healthy. “Caring for bats here benefits people and the ecosystem. In reality, everything is connected.”
And if a life well lived includes tequila, whether as agricultural income or as a nighttime drink, then a desert landscape filled with screeching, swooping creatures and flourishing life benefits us all.
*This article was published on BBC Future. Click here if you want to read the original version (in English).
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* A species of bat “lost” for 40 years is rediscovered
* The city where the migration of bats from Mexico is a total spectacle
click here to read more stories from BBC News Mundo.
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