The popularity of LED bulbs is having a devastating effect on wildlife.
Light from LEDs can wreak havoc with the internal body clock of nocturnal animals, which can destroy migration patterns and reproductive cycles.
Light-Emitting Diode, or LED, bulbs produce a sharp and intense light which is unnatural for many nocturnal animals and can be as damaging as ‘the same brightness of midday sun’, according to scientists.
The latest findings could help protect migrating birds, as well as nocturnal animals whose predatory and breeding behaviour is being endangered by LED lights.
LED lights are an increasingly popular choice, thanks to their brightness and low cost, but this success is coming at the expense of wildlife. The sharp and intense light is unnatural for many nocturnal animals and is wreaking havoc with their internal body clocks (stock)
Sea turtles and insects are especially vulnerable to the bright lights, experts warned.
Lead author Professor Travis Longcore, a spatial scientist at the University of Southern California, said: ‘Outdoor environments are changing rapidly and in ways that can impact wildlife species.’
Professor Longcore and his team have developed a tool to identify the shades of light that carry the most threat to animals.
Professor Longcore said: ‘We provide a method to assess the probable consequences of new light sources to keep up with the changing technology.’
Light pollution poses a growing crisis worldwide – not just to humans’ physical health, but the natural balance of the environment.
Cities and towns now illuminate the night sky with such intensity that much of Earth resembles a bright, glowing ball from space.
Scientists have spent years studying how light brightness and direction can affect wildlife.
This includes migration, mating, relationships between predators and prey, and the body clocks, known as circadian rhythms, of animals.
The study is an important step in understanding the interaction between human needs and wildlife conservation.
To understand the impact the light was having on the animal, and to find an acceptable compromise between human and animal needs, the researchers focused their research on species where there was the most readily-available data.
Loggerhead sea turtles (pictured) are an endangered species. They have been found to be leaving their beach nests at night and following artificial light inland. This stops them following the moonlight and skittering to the ocean
As a result, the study centred on insects, sea turtles, salmon and the seabird Newell’s shearwater.
By looking at either new or previously published data, the team of researchers combined the amount of spectral light produced by each bulb and compared it to the behavioural change of the animals.
This allowed them to produce a standardised measure, called the Correlated Colour Temperature (CCT), to sufficiently understand how light emission affects animal behaviour.
Researchers found the worst night-time lights are those with blue and white hues, with these lights affecting wildlife three times more than yellow or green shades.
For example, loggerhead sea turtles, an endangered species, have been found to leave their beach nests in the middle of the night to follow artificial light inland.
The bright light from human activity nearby prevents the animals from following the moonlight into the ocean – a key part of their life cycle.
Similarly, bright artificial lights are attracting migrating juvenile salmon, putting them at greater risk from predators.
However, this is not only restricted to marine animals.
Experts have found a link tying global declines in insect population numbers with light pollution, according to Prof. Longcore.
It is hoped that by understanding the damage these lights cause to wildlife, people will be able to choose lights that reduce their individual impact.
The study focused on just four groups of animal, but future studies will likely broaden the investigation into more species worldwide.
A central component of the study is a new database which shows how two dozen different types of artificial lighting affects wildlife.
The matrix is called ‘Rapid Assessment of Lamp Spectrum to Quantify Ecological Effects of Light at Night’ and can be used to balance the needs of nature and people.
Today, regulations limiting light direction or intensity fail to account for the different hues of LED lights.
This image shows the level of light pollution over the US in 2012 from the International Space Station (ISS). LED lights are expected to comprise 69 per cent of the global market by 2020, compared to just 9 per cent in 2011
Professor Longcore added: ‘If we don’t provide advice and information to decision makers, they will go with the cheapest lighting or lighting that serves only one interest and does not balance other interests.
‘We provide a method to assess the probable consequences of new light sources to keep up with the changing technology and wildlife concerns.’
In the UK, hundreds of thousands of street lights have been replaced by LEDs as dozens of councils replace the older mercury and sodium street lights with the cheaper LED alternatives.
The main reason for the shift, except for lower cost, is that they are thought to reduce energy use by up to 40 per cent.
LED lights are expected to comprise 69 per cent of the global market by 2020, compared to just 9 per cent in 2011.
They are popular because they have many uses, conserve energy and last longer than other lamps.
Research has also shown that LEDs, which are also increasingly being used to light gardens and barbecues for late night summer parties, are affecting humans too.
As well as making it harder for people to get to sleep, it is increasing the risk of breast cancer and other potentially fatal illnesses.
This exposure to such conditions comes as the bright lights are triggering a lack of melatonin, a hormone produced during sleep.
Public Health England (PHE) has warned they could also cause long-term damage to people’s eyesight, leaving them with health problems akin to ‘permanent jet lag’.
PHE has suggested local authorities should limit the use of LED street lights.
Concerns have been echoed in the US, where a report by the American Medical Association warned blue light emitted by LEDs can affect sleep rhythms, leading to ‘impaired daytime functioning’ and obesity.
The research was published in the Journal of Experimental Zoology Part A: Ecological and Integrative Physiology.
The news comes as new research revealed that animals are becoming increasingly nocturnal to avoid contact with humans.
The shift has been observed in six continents, and could dramatically alter animals’ reproductive habits, survival rates and food chains worldwide.
Researchers observed the habits of 62 species, using GPS tracking and motion-activated cameras to track their behaviour in relation to human activity.
The growing trend could dramatically increase the impact of LED bulbs on species worldwide.