Artificial Light at Night and Wildlife Welfare

Artificial light at night (ALAN) is transforming natural darkness across the globe. Its effects on wildlife range from altered behaviour to population decline, with significant welfare implications.

Key Facts

Light pollution affects over 80% of the world population and has spread at approximately 2% per year in brightness in recent decades
Migratory birds are disoriented by artificial light, leading to building collisions that kill an estimated 100-600 million birds annually in North America alone
Sea turtle hatchlings use natural light gradients to navigate to the ocean; artificial coastal lighting causes disorientation and predation mortality at nesting beaches
Light pollution suppresses melatonin production in wildlife as in humans, disrupting circadian rhythms, reproductive cycles, and immune function
Moths attracted to artificial lights suffer exhaustion from prolonged circling and fail to fulfil their essential pollination role; insect populations near lights show marked declines

Welfare Considerations

Artificial light at night causes welfare harm through multiple mechanisms simultaneously. For individual animals, acute welfare impacts include building collision injuries, predation of disoriented migrants, hatchling turtle mortality, and exhaustion from light-attraction behaviour. Chronic impacts include disrupted sleep-wake cycles, suppressed reproductive success, altered foraging behaviour, and reduced immune function — harms that operate at the individual level while also contributing to population decline. The scale of light pollution-related wildlife welfare harm is immense but largely invisible because the causes are distributed across billions of individual light sources rather than concentrated at identifiable harm sites. Individual, community, and policy-level responses can all contribute meaningfully to reduction.

What You Can Do

Switch outdoor lights to motion-activated controls or timers that minimise unnecessary overnight illumination
Use red or amber wavelength lights where illumination is needed near wildlife habitats — these are less disruptive to most species
Support Dark Sky designation campaigns for areas with important wildlife populations
Turn off unnecessary indoor lights visible through windows during bird migration seasons (spring and autumn)
Advocate for local authority lighting policies that specify wildlife-sensitive design for street and public lighting