Light pollution prolongs avian activity.

Light pollution disrupts light–dark cues that organisms use as timetables for life. Although studies—typically focusing on individual species—have documented earlier morning onset of bird vocalization in light-polluted landscapes, a synthesis of light pollution effects across species, space, and season is lacking. We used a global acoustic dataset of more than 60 million detections, representing 583 diurnal bird species, to synthesize effects of light pollution on avian vocalization. On average, light pollution prolonged vocal activity by 50 min. Light pollution responses were strongest for species with large eyes, open nests, migratory habits, and large ranges and during the breeding season. Prolonged activity may confer negative, neutral, or positive fitness effects; documenting these fitness effects and curbing light pollution are challenges for 21st-century conservation. Editor's summary: Light pollution has become ubiquitous across much of the planet. This situation has the potential to widely affect a variety of species because most living organisms have evolved to respond, in one way or another, to the circadian light-dark cycle. Pease et al. looked at the influence of light pollution on activity patterns in more than 500 species of birds globally. They found that birds were generally vocal for nearly an hour longer in the presence of light pollution. Furthermore, birds that are more exposed, or entrained, to light were more affected, such as those with large eyes and open nests. —Sacha Vignieri [ABSTRACT FROM AUTHOR]