Artificial light at night and terrestrial fauna: A review on research trends and knowledge gaps

With ongoing urbanization, artificial light at night (ALAN) is increasing worldwide, and its effects on wildlife are becoming better documented. However, more detailed knowledge is still required to inform actions and policy strategies for reducing light pollution effectively. We conducted a topic analysis using topic modeling methods, focusing on the investigated effects of ALAN on terrestrial fauna. Based on a corpus of 724 abstracts selected from the Web of Science Core Collection and Scopus databases, the most frequently studied taxa were passerines, bats, rodents, lepidopterans, coleopterans, and dipterans. Several taxonomic groups, including Carnivora, birds of prey and soil fauna, were poorly studied. Research on ALAN effects on wildlife primarily focuses on behavioral changes, while its physiological effects remain comparatively understudied. Population- and community-level responses are also underrepresented, although interest in these scales of investigation is increasing rapidly. The effects of light spectrum on wildlife remain largely understudied, despite its significant influence on animal behavior and physiology. Similarly, the impacts of lighting dimming and switch-off on wildlife are mostly unexamined, limiting our ability to evaluate these mitigation strategies. We therefore advocate for further research on underrepresented taxa, such as soil fauna or Carnivora, and under a broader range of lighting conditions, including light spectrum, intensity and exposure duration, in order to inform the design of lighting to support wildlife conservation.