Glowing green: A quantitative analysis of photoluminescence in North American bats

Photoluminescence produced by excitation with ultraviolet light has been documented in an increasing number of nocturnal-crepuscular mammal species. Here, we provide a quantitative analysis to confirm visual observations of UV-induced photoluminescence in six North American bat species. We used museum specimens to examine wavelength and irradiance at peak photoluminescent emission, within and among species and sexes. We observed green photoluminescence on the wings, uropatagium, and hind limbs of all 60 museum specimens examined. Spectral scans revealed a consistent emission peak between 538 and 560 nm corresponding to the observed green color. We found that Brazilian free-tailed bats (Tadarida brasiliensis) and big brown bats (Eptesicus fuscus) exhibited higher irradiance levels than other species. We found no differences in irradiance or wavelength between sexes and irradiance was not related to specimen age. Our results suggest that photoluminescence is homologous in origin for the species we examined and may serve an important role in social behavior. We emphasize the need for further exploration into the evolutionary and functional roles of photoluminescence across mammalian taxa.