Light Pollution and Biodiversity: How Artificial Light Harms Wildlife

Artificial light at night disrupts the behaviour, navigation, and physiology of countless species. From sea turtle hatchlings to migratory birds, light pollution causes measurable welfare harm to wildlife globally.

Key Facts

Global light pollution is increasing by approximately 10% per year in intensity and extent
Sea turtle hatchlings navigate to the ocean using the brightness of the horizon — artificial lights disorient them
An estimated one billion birds die from building collisions annually in the US alone, partly light-related
Light pollution disrupts melatonin production in mammals, affecting sleep, reproduction, and immune function
Insects are attracted to and killed by artificial lights in vast numbers, disrupting food webs
Light pollution causes coral to spawn at wrong times, reducing reproductive success
Dark sky reserves now protect some areas from light pollution for both human and wildlife benefit

Welfare Considerations

Light pollution is a pervasive but underappreciated welfare threat. Individual animals experience direct suffering: sea turtle hatchlings crawl towards roads instead of ocean, exhausting themselves and dying from predation or dehydration; birds collide with illuminated buildings; insects are killed in enormous numbers by attraction to lights. Physiological effects including disrupted circadian rhythms affect health over time in nocturnal and crepuscular species. Solutions exist at both individual and municipal levels, making light pollution one of the more tractable wildlife welfare problems.

What You Can Do

Switch outdoor lights to motion-activated, downward-directed, and warm-spectrum LEDs
Advocate for your town or city to adopt dark sky ordinances limiting unnecessary outdoor lighting
Turn off lights during peak bird migration seasons (spring and autumn) in tall buildings
Support the International Dark-Sky Association and dark sky reserve designations near you
Participate in sea turtle nesting beach monitoring and light management programmes