Mapping the luminous intrusion: a nationwide multidecadal emerging bivariate cluster analysis of bat habitat’s exposure likelihood to nighttime light

Artificial nighttime lights can adversely impact animal behavior, particularly in nocturnal species. Evidence shows that bats can become inactive due to night lights and may avoid trees bathed in such light, consequently decreasing nocturnal pollination frequency. Although numerous biological studies have been conducted to understand the alteration in bat behavior due to artificial night lights, mapping the intrusion of nighttime light into bat habitats remains largely unexplored. In this study, we aim to visualize the exposure likelihood of bat habitats to nighttime light in the United States over the past 30 years. We propose a novel method known as the "Emerging Bivariate Cluster" which has the potential to pinpoint locations experiencing the most significant exposure likelihood of bat habitats to nighttime light over time. Our results show that the low count nighttime light value is decreasing for 24.9% of bat habitats in the contiguous United States. Additionally, 1.4% of bat habitats are likely to experience persistent exposure over the years. Our analysis reveals significant disparities in hotspot intervention patterns across different regions, highlighting the probable areas where light pollution is escalating. The insights gleaned from this study illuminate critical areas for future research and conservation efforts, pinpointing specific locations where the impact of artificial nighttime lighting on bat habitats is most likely to be pronounced. By highlighting these areas, our findings offer a roadmap for biological scientists seeking to delve deeper into the effects of light pollution on nocturnal wildlife. Moreover, the identification of these key exposure likelihood zones provides a valuable foundation for developing targeted mitigation strategies, aiming to preserve bat populations and maintain ecological balance. This research not only contributes to our understanding of the spatial–temporal patterns of light pollution but also emphasizes the necessity of implementing informed conservation practices to safeguard the natural nocturnal environment.