fieldnotes

A Tool to Solve Migration Mysteries

Studying environmental DNA provides clues to bat behavior
by Shaena Montanari
When nectar-feeding bats stop at a flower for a snack, they leave small clues behind—specifically saliva, which contains their DNA. Dr. Kristen Lear, BCI’s Agave Restoration Program Manager, and colleagues are developing a way to use the traces of bat DNA for conservation.

For the past few years, Dr. Lear’s team has been examining whether they could use environmental DNA, or eDNA, to detect the presence of nectar-feeding Mexican long-nosed bats (Leptonycteris nivalis) on agave flowers, which grow throughout Texas, New Mexico, Arizona, and Mexico.

Recently, Dr. Lear and colleagues published a paper that shows sampling for eDNA on the blossoms works and can detect the presence of Mexican long-nosed bats.

A portrait photograph of a long skinny green/yellow agave flower tree situated in a residential neighborhood area nearby a street and house on a bright sunny day
Photo: Dr. Kristen Lear
A black minimalistic digital icon illustration of three short small trees situated on top of the ground
Swabbing agave flowers for environmental DNA does not harm plants.
A landscape photograph of two individuals from the Bat Conservation International team surveying for Mexican-long nosed bats in the Trans-Pecos region of Texas as one of the individuals is examining an agave flower tree and the other is inspecting a sample test in the afternoon
BCI’s team and partners survey for Mexican long-nosed bats in the Trans-Pecos region of Texas.
Photo: Dr. Kristen Lear
Now, BCI and collaborators are developing field sampling protocols for large-scale deployment.

“eDNA surveys will allow us to survey for these nectar bats across large areas and try to find their migratory corridors,” Dr. Lear says.

“Swabbing agave flowers for eDNA is a noninvasive method for both the bats and agaves.” —Dr. Kristen Lear
The migration route of the Mexican long-nosed bat is mysterious. In the United States, females raise their young in Big Bend National Park in Texas and the Bootheel of New Mexico. Better identifying the bats’ migratory corridors can help protect foraging resources between these two important areas.

The eDNA is detectable by swabbing agave flowers that tower high off the ground. A long pole with a large polyester swab attached to the end gets the job done.

“Because swabbing does not involve collecting any flowers, it’s a noninvasive method for both the bats and agaves,” Dr. Lear says. The fact that the sampling does not harm any plants will make it easier to potentially have volunteer science projects in the area to help collect eDNA.

A portrait photograph of Montana Horchler (BCI Restoration Technician) collecting a swab from an agave blossom in the field as she is wearing a green hat, black sunglasses, multi-colored (red and black) flannel, and black gloves standing at the back of an open car
Montana Horchler, BCI Restoration Technician, collects a swab from an agave blossom in the field.
Photo: Dr. Kristen Lear
This past summer, BCI partnered with The Nature Conservancy, Texas Parks and Wildlife Department, and private landowners to sample agave blossoms for traces of genetic material from Mexican long-nosed bats in the Trans-Pecos region of Texas. Dr. Lear says that when they were sampling in Fort Davis, Texas, private landowners were happy to let scientists swab agave blossoms in their backyards.

After collecting samples from more than 40 agave blossoms and analyzing them in the lab, there were, unfortunately, no traces of Mexican long-nosed bats detected from the samples.

They hope to add tests for other bats in addition to the Mexican long-nosed bat, specifically the lesser long-nosed bat (Leptonycteris yerbabuenae) and Mexican long-tongued bat (Choeronycteris mexicana).

Next year, she says, they plan to visit more survey sites across Texas and New Mexico.

“In terms of future applications, it’s not just trying to find that corridor,” Dr. Lear says. “We are hoping that we can use this technology in Mexico to identify key foraging areas and other parts of the migratory routes of these bats.”

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