FLAGSTAFF, Arizona — Researchers have long believed that Mexican long-nosed bats migrate through southeastern Arizona, but concrete evidence had been difficult to obtain without capturing and directly studying the nocturnal animals. Now, a new method utilizes an innovative approach to identify these bats based on the saliva they leave behind while feeding on nectar from plants and hummingbird feeders.
In a collaborative effort, Bat Conservation International, an organization dedicated to the protection of bat species worldwide, partnered with local residents from southeastern Arizona, southwestern New Mexico, and west Texas to initiate this saliva sampling campaign. The collected saliva samples were then examined in a laboratory at Northern Arizona University in Flagstaff, where researchers analyzed environmental DNA (eDNA) to verify the presence of these bats in Arizona, confirming that this region serves as their seasonal habitat.
Since 1988, the Mexican long-nosed bat has been classified as an endangered species under the Endangered Species Act, making it the only bat in Arizona to receive such federal protection. These bats play a crucial role in pollinating desert plants, including species like agave and various cacti. In late January, officials from the U.S. Fish and Wildlife Service and the Arizona Game and Fish Department shared the findings of this research, marking a significant addition to Arizona’s bat species list, which now totals 29. The innovative and non-invasive methods used in this study have also garnered recognition from wildlife managers.
“If biologists were reliant solely on traditional methods to identify these species without eDNA, it could take extensive time and effort to capture a single bat — with no guarantee of success,” explained Angie McIntire, a specialist with the Arizona Game and Fish Department. “By sampling the environment for eDNA, we have added another valuable tool to our resources.”
Every spring, Mexican long-nosed bats embark on an extensive migratory journey from Mexico to the southwestern United States, following the scent of blooming plants rich in nectar, and they reverse this path in the fall. In the summer and fall months, the conservation group engaged everyday citizens, providing them with kits to collect saliva samples from bird feeders as part of their mission.
Inside the university laboratory, microbiology student Anna Riley meticulously extracted DNA from hundreds of samples. She employed advanced machinery to detect bat presence, making use of a syringe to transfer diluted DNA into tiny vials for subsequent analysis in a centrifuge. The laborious process of handling these samples required precision and took months to complete.
“There is a large database containing DNA sequences for most species, and we were able to compare our results against this comprehensive database,” Riley noted. “It’s somewhat like performing a Google search; once we input our DNA sequences, the database helps ascertain that we have identified a bat and even specifies the type.”
Kristen Lear from the conservation group highlighted the successful application of eDNA collection for wildlife tracking in various settings, which led to the idea of applying the same method to bats. “These bats indeed leave behind substantial saliva on blooming plants and hummingbird feeders, which makes it feasible for analysis,” Lear added.
