Skip to main content
U.S. flag

An official website of the United States government

MADISON, Wis. — Mexican free-tailed bats can be infected with the SARS-CoV-2 virus but don’t appear to spread it or become sick, according to a U.S. Geological Survey study published today.


Mexican free-tailed bat
Mexican free-tailed bats are an abundant and widespread species of the Americas. (Credit: Ann Froschauer, USFWS)

Scientists with the USGS monitored 10 captive Mexican free-tailed bats that were exposed to SARS-CoV-2, the virus that causes COVID-19 in humans, for infection and potential bat-to-bat transmission. Five of the bats became infected with the virus and tested positive for 6-18 days. None of the infected bats showed signs of illness and there was no evidence that they spread the virus to healthy bats in shared enclosures.

“As the virus that causes COVID-19 continues to circulate, our study addresses its potential to infect native wildlife populations,” said Jeffrey Hall, a USGS scientist and the lead author of the report. “The findings can help managers understand the risk this virus poses to valuable Mexican free-tailed bats.”

Mexican free-tailed bats are famous for a colony of about 1,500,000 animals that roosts under the Congress Avenue Bridge in Austin, Texas. These popular bats contribute to healthy ecosystems, and they provide critical agricultural services by eating a large amount of insect pests every night. The study addresses concerns that humans may accidentally transmit SARS-CoV-2 to North American bats, such as when bats are handled for scientific or rehabilitation purposes.

The findings suggest that the SARS-CoV-2 virus is not deadly to Mexican free-tailed bats. However, scientists emphasize the need for further research to understand potential impacts of this virus on wildlife should it be detected in wild Mexican free-tailed bats or in other North American bat species. The study is specific to Mexican free-tailed bats and its findings are not applicable to other animals.

“Studying infectious diseases in humans as well as wildlife is critically important because people and animals are tightly interconnected through our shared environments,” said Jonathan Sleeman, director of the USGS National Wildlife Health Center. “Our well-being depends on the health of living things around us.”

The USGS partnered with Louisiana State University and the Texas Parks & Wildlife Department on the study, which was conducted in a contained laboratory setting under biosafety level 3 conditions. For more information about USGS wildlife disease research, please visit the USGS National Wildlife Health Center website.

In general, people should not handle bats and should enjoy them from a distance. If you find a sick or dead bat, follow the guidelines available on the USGS website.

Brazilian free-tailed bat (Tadarida brasiliensis), a migratory insectivore known to consume insect pests of agriculture.
Mexican free-tailed bats are also known as Brazilian free-tailed bats. (Credit: Ernest Valdez, USGS)

Get Our News

These items are in the RSS feed format (Really Simple Syndication) based on categories such as topics, locations, and more. You can install and RSS reader browser extension, software, or use a third-party service to receive immediate news updates depending on the feed that you have added. If you click the feed links below, they may look strange because they are simply XML code. An RSS reader can easily read this code and push out a notification to you when something new is posted to our site.