The primary mission of the Great South Bay Audubon Society is to advocate for the conservation of habitats for native birds and other native wildlife on Long Island.

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GSBAS Chapter Articles

Our Slowly Disappearing Night Sky - A Growing Light Pollution Crisis

November 7, 2018

By Gail Marquardt Black

Less than a century ago our view of the night sky was starry and spectacular. Today millions of people on earth can no longer view the Milky Way at night, a disturbing result of the advent and spread of electricity. With the demand for newer and brighter night lighting, the evening sky has been slowly disappearing. A 2016 study revealed that 80% of the world population live under ‘skyglow’—the artificial brightening of the night sky; in Europe and the US 99% of the population no longer experience natural night.

Besides affecting a natural night view of the universe, increasing and widespread use of excessive and inappropriate artificial light, called ‘light pollution’, is negatively impacting the world’s ecosystems. All life---amphibian, bird, mammal, invertebrate and plant--- is genetically adapted to day/night/seasonal cycles, which should be controlled by earth’s predictable light rhythm. Human disruption to this natural light cycle, caused by light pollution, is now affecting behavior and physiological processes of animals and plants, with unknown long-term ecological consequences.

Both diurnal (day active) and nocturnal (night active) animals are affected by light pollution. Nocturnal animals---such as moths, bats, frogs---seem more noticeably affected by it and its impact on their habitats. Light pollution is changing animal behavior patterns and reproduction rates and making them more vulnerable to predators. Examples are numerous: sea turtle hatchlings who find the sea by the night sky have been drawn inland due to artificial beach lighting, resulting in the deaths of millions yearly; night-croaking frogs in wetland areas are impacted in their nocturnal breeding rituals, resulting in population decline; night-pollinating insects, such as moths and fireflies, display lowered pollination activity, as well as population reduction.

Birds are affected by light pollution in many ways. Recent studies have revealed subtle changes in bird breeding rituals/timing and feeding patterns, as increased use of artificial light impacts day length; future effects from this are a concern. Known for centuries, bright light at night surrounded by darkness disorients migrating or night-hunting birds and cause them to change their flight paths towards it; disorientation can lead to repeated chirping, circling until dawn, total exhaustion, building collision and death. A major mortality threat currently for fall and spring migrating birds (mainly night-migrating passerines), light pollution actually disrupts the celestial and magnetic orientation mechanisms birds possess, which have evolved to work with dimmer natural light sources. “Lights Out” programs that dim city lights during fall and spring migratory seasons, organized by diverse environmental groups in many US cities, are being adopted to help mitigate bird-kills from urban light pollution building collisions. Manhattan’s week-long 9/11 Memorial Tribute to Light beamed skyward 3½ miles initially caused extensive bird-kills, but now shuts down its powerful beams for short periods as needed to release the thousands of disoriented birds vocalizing and circling around them--an improvement to the problem.

Close to one million birds die yearly as a direct result of light pollution. ‘Spill lighting’ from building window interiors in urban, suburban and rural areas, as well as use of unshielded spotlighting, are ongoing major bird mortality threats. Other dangers are lighted offshore drilling platforms, which cause circling behavior and seabird kills, and lighted communication towers. When used, strobe lighting has greatly reduced bird mortality; intermittent lighting and light color manipulation also show promise in reducing future risks.

Humans are genetically adapted to a natural day/night cycle, bright days and dark nights, crucial for overall health. Research has shown that disruption of this circadian rhythm with artificial light can produce serious health problems. A 2016 American Medical Association report found that blue light (in most outdoor LED lighting, computer screens, TVs, electronic displays, fluorescent bulbs) is particularly harmful to human health and recommends use of lighting with 3000 K color temperatures and below.

Modern society necessitates artificial night lighting for certain requirements, such as safety and commerce, but excessive use increases greenhouse gas emissions and contributes to climate change. Much artificial night lighting is inefficient and poorly targeted, overly bright and improperly shielded and, many times, completely unnecessary. In urban and suburban areas it often can be seen: on/in houses, offices and factories; in street and park illumination; in outdoor sports areas and parking lots.

Wise use of outdoor lighting can help control light pollution’s harmful effects, if you:

  1. Install outdoor lighting only where and when needed.
  2. Shield light fixtures so light points down, not up *; control window “light spill” with blinds/shades.
  3. Use timers, dimmers, motion sensors for energy saving and brightness control.
  4. Minimize blue light emissions which endanger wildlife and harm human health.*

Further information:

See the chart of acceptible light fixtures

American Bird Conservancy:

International Dark-Sky Association: