Skyglow acts like a permanent, artificial twilight that confuses animals relying on starlight for navigation. In urban areas, streetlights create bright corridors that break up natural darkness. Migrating birds often mistake these concentrated light sources for clear paths, leading them off course and into dangerous collisions with buildings. Many insects fly directly into lights until they die of exhaustion. This disorientation ripples through the food web.
In rural ecosystems, even faint skyglow alters the internal clocks of wildlife. For many amphibians, light signals the time to breed; artificial glow can trigger mating behaviors too early or too late in the season. This mismatch often means offspring hatch when food is scarce. Similarly, nocturnal mammals rely on specific light levels to time their foraging. When the sky never gets truly dark, predators and prey lose their tactical advantage. Prey animals may stay hidden longer to avoid detection, skipping essential feeding windows. This constant state of alertness increases stress and lowers survival rates. The loss of a dark sky essentially rewrites the biological schedules that species have followed for millennia.
