Scientists Confirm Endangered Bats Are Migrating in Arizona for the First Time, Using DNA Clues Found in the Environment
Researchers and citizen scientists took samples of environmental DNA from saliva on backyard hummingbird feeders and agave plants to identify Mexican long-nosed bats
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Each spring, pregnant Mexican long-nosed bats fly north from Mexico to parts of southern Texas and New Mexico, feasting on nectar from saguaro, cardon and organ pipe cacti as they migrate.
Sometimes, as the endangered creatures make the long, 700-mile journey northward to give birth, they stumble upon a hummingbird feeder in a backyard. Filled with a sweet, sticky, sugary solution, the feeders are hard to resist—and the bats eagerly slurp their fill.
Now, researchers are using the spit these nocturnal mammals leave behind to identify them. Bat Conservation International, a nonprofit focused on conserving bats and their ecosystems, recently used DNA from the creatures’ saliva to—for the first time—confirm they’re passing through southeastern Arizona during their migrations. Scientists had long suspected Mexican long-nosed bats were migrating into Arizona, but they didn’t have proof, until now.
This finding not only expands the known range of Mexican long-nosed bats, but it could also have important implications for research and conservation work. The species is now the only known bat in the state that’s listed as endangered under the Endangered Species Act. And since scientists learned that Mexican long-nosed bats are making their way into Arizona, they can take steps to protect the animals’ roosting sites and maintain a healthy foraging habitat. For example, they’re already encouraging Arizona residents to plant night-blooming native plants and agaves to help the bats thrive.
“We’re seeing more bat species using the edge of their ranges in areas that they aren’t usually found,” says Kristen Lear, who leads Bat Conservation International’s agave restoration program, to Public News Service’s Alex Gonzalez. “That could be what is happening here … all of the modeling shows that [Arizona] is actually going to become more important for these bats in the future.”
The group recruited citizen scientists from southeastern Arizona, southwestern New Mexico and west Texas. Bat Conservation International sent the participants swab kits, as well as instructions on how to gather samples from their hummingbird feeders. Scientists also took samples from agave blooms, which are one of the Mexican long-nosed bats’ favorite sources of nectar.
Then, the organization sent the samples to a laboratory at Northern Arizona University for testing. There, researchers analyzed the samples for what’s known as environmental DNA (eDNA), or tiny bits of genetic material that animals and plants leave behind. In addition to saliva, eDNA can include feces, fur and hair, skin cells and mucus.
“It’s a pretty new technique,” says Faith Walker, a geneticist at Northern Arizona University, to the Arizona Republic’s John Leos. “And it had never been applied to nectar-feeding bats before, so it was pretty innovative.”
As expected, researchers at Northern Arizona University found Mexican long-nosed bat DNA in the samples. This technique gives scientists “an additional tool for our toolkit,” says Angie McIntire, a wildlife biologist who specializes in bats with Arizona’s Game and Fish Department, to the Associated Press’ Ty O’Neil and Felicia Fonseca.
Without eDNA, biologists could “spend hours and hours trying to catch one of these bats, and even then, you’re not guaranteed to be successful,” McIntire adds.
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Mexican long-nosed bats (Leptonycteris nivalis), also known as greater long-nosed bats, have been listed as endangered under the Endangered Species Act since 1988, according to the U.S. Fish and Wildlife Service. The species has also been listed as endangered in Texas since 1988 and New Mexico since 1990, according to the Texas Parks and Wildlife Department.
They are relatively large bats, measuring between 2.75 and 3.75 inches long from head to tail. Mexican long-nosed bats use their lengthy tongues—which can measure up to three inches long and are covered in hair-like structures—to extract nectar from flowering plants; they also sometimes eat soft fruit and bugs.
Mexican long-nosed bats are often confused with another species, the lesser long-nosed bat (Leptonycteris yerbabuenae). The two species are nearly identical in appearance, and they sound similar when they echolocate. Before scientists began using eDNA, the only way to differentiate between the two was to capture a bat and then measure the animal’s third finger. (Mexican long-nosed bats have the longer third finger.)
But being captured can be stressful for the bats. Collecting eDNA, on the other hand, is a completely noninvasive process that does not involve the animals at all. Projects like this one also give citizen scientists a chance to get involved with research and conservation.
“Citizen science means that you’re plugging what you discover into something bigger than yourself,” says Al Bammann, a resident of Portal, Arizona, who participated in the eDNA swabbing project, in a statement. “It is the bird watcher who reports their daily observations that is helping in the long term… It all helps to understand what is there and what is changing.”
This is not the first time scientists have turned to eDNA to investigate elusive animals. They’re using eDNA to identify individual polar bears wandering through the vast snowy landscape of the Arctic and to detect a rare and secretive marsh bird called the black rail.
They can also use eDNA to reveal other unknowns, like the abundance of fish in a certain body of water. Researchers also recently discovered that electricity generated by electric eels is likely transferring eDNA into fish larvae, which might be causing genetic modifications.
