Discovery of Fluorescent Bats in North America

Researchers from the University of Georgia's Warnell School of Forestry and Natural Resources have made a groundbreaking discovery: six species of North American bats emit a green fluorescence when exposed to ultraviolet (UV) light. This phenomenon, documented in the peer-reviewed journal *Ecology and Evolution* on July 28, 2025, marks the first recorded instance of bats glowing under UV light in this region. The species identified include the big brown bat (*Eptesicus fuscus*), eastern red bat (*Lasiurus borealis*), Seminole bat (*Lasiurus seminolus*), southeastern myotis (*Myotis austroriparius*), gray bat (*Myotis grisescens*), and Brazilian free-tailed bat (*Tadarida brasiliensis*). The study involved examining 60 preserved specimens from the Georgia Museum of Natural History, all of which exhibited the same green glow in their wings, hind limbs, and the uropatagium.

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The consistency of the fluorescence across all examined specimens suggests a genetic basis rather than an environmental or dietary influence. Lead author Briana Roberson indicated that the glow likely points to a shared genetic origin, potentially inherited from a common ancestor. Co-author Steven Castleberry noted, “Our data indicate the trait may have come from a common ancestor. It could be a leftover adaptation — something that once had a function but doesn’t anymore.” This discovery challenges existing assumptions about bat biology, particularly regarding their nocturnal adaptations.

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Despite the intriguing nature of this finding, the researchers remain uncertain about the glow's purpose. They ruled out mate attraction and interspecies signaling, as the glow does not vary between sexes or species. Castleberry remarked, “It’s cool, but we don’t know why it happens. What is the evolutionary or adaptive function?” The team speculated that the fluorescence might serve as a form of communication among bats, similar to the greenish-blue glow observed in Mexican free-tailed bats, but further research is needed to confirm this hypothesis.

Scientists Just Discovered That Bats Can Glow in the Dark, This Isn’t a Joke or CGI

The phenomenon of fluorescence is not unique to bats; several other mammals, including flying squirrels and opossums, also exhibit similar traits. This discovery adds to a growing body of research exploring natural fluorescence in various animal groups, including deep-sea organisms and certain insects. The potential implications of this trait for bat behavior, communication, and ecological interactions remain largely unexplored.

Scientists Just Discovered That Bats Can Glow in the Dark, This Isn’t a Joke or CGI

As researchers continue to investigate the significance of this fluorescent trait, the next steps will involve studying live bat populations in their natural habitats. Understanding whether the glow affects behavior or communication will be crucial in deciphering its evolutionary role. Until then, the reason behind the glow remains one of nature's intriguing mysteries, inviting further exploration into the hidden aspects of bat biology.

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• “It’s cool, but we don’t know why it happens.” — Steven Castleberry, Wildlife Ecology Professor

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• “Castleberry said: Our data indicate the trait may have come from a common ancestor.” — Steven Castleberry, Wildlife Ecology Professor

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• “According to lead author Briana Roberson: The color and placement of the glow point toward a genetic basis.” — Briana Roberson, Lead Author

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This discovery not only sheds light on the biology of bats but also serves as a reminder of the myriad ways in which animals interact with their environment, often in ways that remain hidden from human observation.

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