Bats like dimmer lights: lunar phobia as a luminosity threshold phenomenon on Neotropical bats (Mammalia: Chiroptera)
A lunar phobia is a behavioral trait in which the individual alters or ceases its nocturnal activity during periods of strong lunar illumination found throughout the animal kingdom. Current evidence indicates the changes reflect predator/prey detectability due to increased visibility. The study hypothesizes whether bat activity is more negatively influenced by a discrete threshold of high lunar illumination (nights with ≥ 90% of moon exposure) rather than a continuous linear response to variation in moon exposure. A 1202 mist net bat captures dataset from a preserved area in Northeast Brazil was used to test this hypothesis. A stepwise model was built, using Bayesian information criterion, to determine the effect of lunar luminosity (either as continuous moon exposure or discrete threshold parameter), environment (open vegetation vs canopy-covered), and season (dry/wet). The final model selected showed a significant negative threshold effect of nights above 90% of moon luminosity compared to a weaker non-significant effect of continuous moon exposure variation. The selected model also found a positive effect of forested environments and the wet season in the total number of bat captures. The model was able to detect a significant decrease in captures for the most abundant species, Artibeus planirostris. Our findings support the hypothesis that bats (especially frugivorous) present lunar phobia, which respond in a negative nonlinear fashion to high luminosity, possibly to avoid predation.
KeywordsChiroptera Moon Luminosity Neotropics Nocturnal activity
We would like to extend our gratitude to the staff of the Guaribas Biological Reserve for all support and knowledge shared during the field data collection. A personal thank you to Whitney Howell, MSc, for proofing the final manuscript and offering invaluable input on the writing and structure of the text. CGZ’s work is supported by a doctorate scholarship granted by FAPESB.
CGZ performed the original fieldwork, built the conceptual framework of the paper, and wrote the manuscript. LMMA performed the statistical analysis, guided data interpretation, and contributed to the manuscript. LCSL mentored and curated the original fieldwork, participated in the statistical analysis, and contributed to the manuscript.
Compliance with ethical standards
The authors declare that they have no conflict of interests.
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