Light pollution disorienting animals that navigate by the night sky

Skyglow forces dung beetles to abandon the Milky Way as their compass.

• The era of electric lighting, which began in the late 19th Century, allowed humanity to extend days into the night with the flick of a switch.
• As technology has progressed, it has only become simpler and cheaper to light up the world more brightly.

How does the Nature’s clock work?

• The Sun is basically like a clock.
• The reliable rhythm of night and day gives plants and animals signals for natural cycles of feeding, mating, migrating and navigating.
• Humans are altering this natural rhythm by flooding the world with artificial light.

• In the journal Current Biology, the researchers show that South African dung beetles (Scarabaeus satyrus) are unable to use their star compass under light-polluted skies.
• Researchers tested how dung beetles responded to two types of artificial light:
  • a single bright beacon
  • the dull glow a nearby city might produce
• Both kinds disoriented the dung beetles, throwing them off their usual path.
• When exposed to the bright light, the beetles headed toward that, and when exposed to the ambient light, they went in circles.

• Increasing urbanization
• installation of new streetlights
• security floodlights
• outdoor ornamental lighting

• Habitat disturbance: The light that beams from skyscrapers, office blocks, streetlights and homes spills into the habitats of animals.
• It scatters into the atmosphere, creating a sky glow that can extend around 150 miles(241km) from large towns and cities.
• Many animals seem to navigate using the stars (birds, seals, and moths), the fading of the night sky could be having similar effects on other species as well.
• There are over 250,000 birds a day that are getting lost in their migration or light pollution patterns.
• The impacts of light pollution spill into almost every ecosystem.
  • Artificial light has huge impact on almost every part of insects' behaviour.
    • Light pollution, for example, can changethe foraging behaviour of nocturnal insects, making it harder for them to find food, and for creatures such as fireflies, which rely on bioluminescence to attract a mate, artificial light can confuse males and make it difficult for them to find females.
  • Fish: Artificial light can affect fish by suppressing melatonin, the hormone that controls sleep patterns, setting an internal clock for processes like reproduction and growth.
  • Turtle: It disrupts the nesting behaviour of turtlesand draws newly-hatched marine turtles away from the sea, increasing the risk they will die before they ever reach the water.
  • Bats: Some species of bats associate artificial light with predators, meaning in brightly-lit cities they can be left with "nowhere for them to go.
  • Coral reefs: Even coral reefs are damaged by light pollution.

• Sloveniapassed a national law to reduce light pollution in 2007, requiring outdoor lighting to be shaded and not exceed certain levels of brightness.
• Puerto Rico, which has three bioluminescent bays, passed light pollution legislation in 2008.
• France introduced laws on outdoor lighting in 2019, leading to a 6% decreasein light pollution.
• Croatiapassed a law restricting lighting levels in 2019.
• At least 17 US statesand the District of Columbia have some form of light pollution legislation.

Light Pollution is just one additional stress to the whole ecosystem that needs to be taken care of immediately." Cities can put lights on dimmers and install motion sensors or timers to help. Instead of blue and white lights that mimic daytime, amber red lights are a better option.