Artificial light at night disrupts the biological rhythms, navigation, foraging, and reproduction of nocturnal animals, with welfare consequences for bats, moths, turtles, birds, and many other species.
Key Facts
The global extent of artificially lit areas is increasing by approximately 2% per year
Sea turtle hatchlings navigate by the natural brightness of the ocean horizon, which is disrupted by coastal lighting
Around one third of all vertebrate species and two thirds of invertebrates are nocturnal or crepuscular
Migratory birds are disoriented by lit buildings, with an estimated one billion birds dying from building strikes annually in the US
Moths are attracted to artificial lights, disrupting pollination behaviour and making them vulnerable to predation
Welfare Considerations
Light pollution causes direct welfare harm through disorientation leading to fatal collisions, disruption of foraging behaviour leading to malnutrition, and interference with reproductive signalling. Sea turtle hatchlings drawn inland by artificial lights die from dehydration and predation instead of reaching the sea. Moths circling lights become easy prey and fail to pollinate nocturnal flowers. Bats avoiding lit areas lose foraging opportunities near insect-rich light sources while facing artificial selection pressure in their natural habitats.
What You Can Do
Switch to warm-toned, downward-directed outdoor lighting to reduce sky glow and wildlife disruption
Support local campaigns for dark sky designations and lighting ordinances in wildlife-sensitive areas
Turn off unnecessary indoor lights visible from outside during bird migration seasons (March-May and August-November)
Install motion-sensitive lighting rather than permanent illumination where security lighting is required