It is no secret that light pollution has an impact on wildlife.
For billions of years, all life has relied on Earth’s predictable rhythm of day and night. It’s encoded in the DNA of all plants and animals. By introducing artificial light to the nighttime landscape, humans have disrupted this natural cycle and altered species’ behavior and biology. Particularly, light pollution can disorient or inappropriately attract species to lit areas, interfere with ecological interactions like predator-prey relationships, interrupt habitat connectivity, disrupt natural circadian rhythms, and influence species’ ability to detect seasonality.
For decades, the research community has sounded the alarm on the ecological impacts of light pollution and in recent years there has been a stark increase of studies on the topic. IDA’s Artificial Light at Night (ALAN) Research Literature Database indicates that the number of academic studies focused on animals and light pollution has more than quadrupled in the last five years. Here’s a snapshot of what these studies are bringing to light and what we can do about it:
Light Pollution is Contributing Significantly to Insect Apocalypse
Insects are very sensitive to artificial light at night which can affect their circadian rhythms, mating rituals, and ability to navigate. Studies have shown that lights at night impact nocturnal pollinators, including many species of moths.
“We strongly believe artificial light at night – in combination with habitat loss, chemical pollution, invasive species, and climate change – is driving insect declines…We posit here that artificial light at night is another important – but often overlooked – bringer of the insect apocalypse.” – Avalon C.S. Owens et al.
There has been a particular focus on insects lately as researchers recently identified light pollution as a ‘key bringer of the insect apocalypse’ and another study warned that fireflies could face global extinction due to excessive light at night. Severe insect decline is particularly concerning considering their place in the food web and important role in pollinating food crops.
Light Polluted Cities are Deadly for Birds
The Yale School of Forestry and Environmental Studies reports that 40% of the world’s 11,000 bird species are in decline. Several studies indicate that light pollution plays a major factor in this decline, causing fatal collisions with lit buildings, impacting bird’s ability to navigate, and even influencing the transmission of diseases like West Nile Virus.
Bright Lights Disorient Sea Turtle Hatchlings
Of all the species threatened by shrinking habitats and light pollution, sea turtles are among the most at risk for extinction. Several turtle species are listed as either threatened or endangered in the U.S. and by international organizations, with populations rapidly declining over the past 100 years. Sea turtles are particularly impacted by light pollution, as their hatchlings often become confused by the bright lights of cities as they attempt to navigate from their nests on land to their home in the ocean.
Humans and Wildlife Can Coexist
“With careful planning and collaboration, usually with nearby jurisdictions, managers of parks and other protected lands can be leaders in the control of light pollution and increase enjoyment of natural lands from inner city parks to wilderness areas.” – Travis Longcore and Catherine Rich.
Artificial light at night does have an impact on the natural nighttime ecosystem, but there are steps we can take to limit that impact. In their report, Artificial Night Lighting and Protected Lands: Ecological Effects and Management Approaches, Travis Longcore and Catherine Rich offer land managers practical approaches for lighting environments for human use while also mitigating impacts on wildlife. They provide guidance on how to thoughtfully light various habitats such as shorelines, deserts, dense forests, and urban settings. By carefully considering the characteristics of a habitat and lighting needs, direction, duration, color spectrum, and intensity, landowners can create environments that respect both human and animal needs.
Looking for more research on light pollution and wildlife? Check out IDA’s Artificial Light at Night (ALAN) Research Literature Database.