The impact of urban-related sensory and risk factors on owls: a systematic review

Urbanisation is a globally increasing phenomenon with diverse impacts on biodiversity. Interest in how urbanisation affects raptors is growing because, as top predators, they can be used as bioindicators for ecosystem functioning and sentinels for environmental change. However, a comprehensive synthesis detailing the global-scale impact of urban-related sensory and risk factors on nocturnal raptors (i.e. owls) is lacking. In this review, we examined the literature to identify such factors and to outline their association with behavioural and ecological traits of owls living in urban environments. Overall, we show that several urban-related sensory and risk factors affect owls, with vehicle collisions on roads being the most widely documented across species. Conversely, sensory pollution remains poorly investigated, which is surprising given that nocturnal and acoustic hunters, such as owls, might be severely impacted by artificial light at night (ALAN) and anthropogenic noise. We also highlight a research gap on this topic from the global south, where urbanisation is rapidly increasing. Importantly, we show that roads and sensory pollutants are associated in contrasting ways with many owl behavioural and ecological traits, such as hunting and habitat use. We argue that the interplay among roads, noise and ALAN influences how owls’ prey species use roads, which may turn areas near roads into ecological traps. The severity of their impacts may depend on the intensity and type of anthropogenic noise and artificial lights along roads. Further research in this direction will have important implications for the conservation of owls in urban environments.