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The link between artificial light at night, street lights, light pollution, biodiversity destruction, nocturnal fauna, bats, insects, and birds is becoming more evident in modern environmental science. It has been suggested that too much light during the night not only causes comfort for humans but also becomes a serious threat to the environment. Research concerning artificial light at night (ALAN) suggests that street lights interfere with the migratory patterns, food gathering, reproductive activity, and sleep of many creatures. Bees hovering around streetlights or migrating birds failing to find their way due to city lights are examples of such interference that remain unnoticed by people.
How artificial street lighting disrupts animal behaviour
While street lamps are associated with safety, visibility, and modernity for humans, these lamps pose a danger to wildlife. Animals adapted to the natural rhythm of day and night, which helped them hunt, navigate and avoid predators. But artificial lighting can disrupt all the usual rhythms of nature and thus change the whole ecosystem.Thus, according to one comprehensive study conducted by the Department of Neuroscience at the Wexner Medical Centre, The Ohio State University, artificial light influences the circadian clock, hormone secretion, daily routines, and reproductive cycles in various species. Experts noted that the natural darkness, which used to be vital for wildlife, was disappearing rapidly due to urbanisation.Animals that are active during the night hours are especially vulnerable to artificial light sources. Not only do they get exposed to potential predators because of the lack of darkness, but also need to find other habitats to stay safe. As explained by NASA Earth Observatory in 2019, nocturnal animals tend to be less active around bright light because it makes them feel unsafe while moving or feeding at night.Besides influencing separate organisms, artificial light may affect the whole food chain in nature. Predators gather around illuminated spaces because insects become easier to catch, while prey species often abandon these areas completely. Over time, this imbalance changes local biodiversity and ecosystem stability.
Why are insects, bats and migratory birds heavily affected by light pollution
Out of all forms of wildlife, it is believed that insects are the most affected by artificial light pollution. Naturally, insects navigate using moonlight and stars; however, artificial street lighting confuses the insects’ navigation capabilities. Thus, moths, beetles, and flies tend to keep circling lights until exhaustion and death.Scientists working at the School of BioSciences, University of Melbourne, noted that pollination in the dark near the street lamp has been substantially reduced since insects prefer to fly towards artificial light sources and neglect the natural pollination process. Consequently, night-time pollinators such as moths contribute less than they used to do previously.Finally, the last species affected by the increased level of night-time artificial light pollution is bats. In some species, there is an aversion to illuminated areas as they attract predators and reduce protection against other threats. The paper ‘Artificial lighting reduces the effectiveness of wildlife crossing structures for insectivorous bats’ indicates that artificial lighting has a detrimental effect on bat activity near the road. In addition, artificial lighting placed beneath wildlife crossings prevents bats from passing through.A totally different but no less dangerous problem is faced by the birds. Migrating birds depend heavily on the natural lights of the sky to guide their path. Bright lights in the city attract the migrating birds to the cities, where they end up colliding with buildings or becoming tired due to a lack of energy. Scientists have discovered that certain birds start their songs and eating too early under artificial lights.
When should street lights be turned off to reduce environmental harm
There is mounting evidence that limiting artificial street lighting after midnight can assist in wildlife conservation. Scientists advise, however, that it will be difficult to come up with a specific time when all the lights need to be turned off, as wildlife activity differs from place to place. As reported in a recent study, discussed by the Centre d’écologie et des sciences de la conservation (CESCO), Muséum national d’Histoire naturelle, CNRS, “part-night lighting,” which involves turning off street lighting at night, when everything is quiet, might minimise ecological disturbances in certain regions. Nonetheless, the scientists emphasised that turning off the street lights would not be beneficial where buildings, signage, and residential lights continue to brighten up the area.Scientists suggest that instead of keeping the streets illuminated throughout the night, it would be better to use lighting systems that target specific regions. Lighting systems include motion sensors, warmer LED lights, and downlighting to decrease any form of artificial illumination without compromising visibility. Sensitive habitats, such as forests, wetlands, and other protected areas, may see the best benefits from part-night lighting.
Balancing public safety with biodiversity conservation
Nevertheless, street illumination plays an important role in terms of transportation and human activity. According to the scientists, better-designed street illumination may serve not only for human safety but for animals’ survival as well. Several communities all over Europe decided to turn off or even remove some of the streetlights in order to save energy and preserve the natural environment.The new research results show that nights are an important element of nature. In fact, dark nights for many species play the same role as their habitat because they have developed certain adaptation processes necessary to survive during nights. Go to Source
