Light pollution from human settlements is disrupting the natural behaviour, physiology and navigation of wildlife on a vast scale, with significant but underrecognised welfare consequences.
Artificial light at night is a welfare stressor whose scale dwarfs most human-caused sources of wildlife harm, yet receives relatively little attention compared to habitat loss or climate change. Sea turtle hatchlings disoriented by coastal lighting die before reaching the ocean. Moths killed around artificial lights die by burning or exhaustion. Migratory birds collide with illuminated buildings in their millions. For each individual animal affected, this represents a preventable death or welfare harm caused by easily modifiable human behaviour. Simple lighting changes — motion sensors, downward-facing fixtures, red spectrum lighting in sensitive areas and light-off periods during peak migration — dramatically reduce wildlife welfare impact from artificial light.