Artificial light at night disrupts migration, reproduction, and predator-prey relationships in numerous species; simple changes to outdoor lighting reduce impacts significantly.
Light pollution is a pervasive and rapidly growing source of wildlife welfare harm that receives far less attention than equivalent threats. Animals relying on darkness for orientation, reproduction, and predator avoidance are chronically disrupted by artificial light. Sea turtle hatchlings that follow bright landward lights instead of dim ocean reflections face dehydration and predation. Insects attracted to lights experience elevated predation and reduced foraging efficiency. Migratory birds attracted to lit buildings collide in vast numbers. Most of these harms are preventable through modest lighting design changes that reduce cost as well as impact.