International light pollution guidelines for migratory species prepared

The Convention on the Conservation of Migratory Species and Wild Animals (CMS) has prepared International Light Pollution Guidelines for migratory species.

The issue of light pollution first emerged with the draft resolutions introduced independently by the European Union and Australia during the Thirteenth Meeting of the Conference of the Parties to the Convention on the Conservation of Migratory Species of Wild Animals (CMS COP 13) four years ago in Gandhinagar. The guidelines were framed following the meet.

CMS COP14, which ended in Uzbekistan’s Samarkand on February 17, 2024, noted that natural darkness has conservation value equal to clean water, air and soil.

Between 1992 and 2017, artificial light emissions have increased over 49 per cent and can severely impact wildlife, including causing behavioural and psychological changes.

The guidelines have been adapted from the ‘National Light Pollution Guidelines for Wildlife Including Marine Turtles, Seabirds and Migratory Shorebirds’, developed by the Government of Australia in 2020.

They recommend reducing light pollution to minimise its effect on wildlife, besides undertaking environmental impact assessments to understand the effects of artificial light on species’ behaviour, foraging, migration, dispersal, survival or reproduction.

Usage of best practices in lighting, managing light time, colour and intensity are also suggested in the guidelines. They also recommend avoiding light spill, using non-reflective, dark-coloured surfaces and avoiding specific colour wavelengths.

They further suggest avoiding lighting in the 20-km radius of an area that is home to wildlife. The guidelines also provide information on managing existing light pollution.

Damaging light

The COP document to address the issue of light pollution enumerates several instances of how light can affect wildlife. The guidelines have been created especially keeping in mind marine turtles, seabirds, migratory shorebirds, migratory landbirds and bats.

Birds — dwelling in marine as well as terrestrial habitats — can be affected by lights from as far as 15 km away, causing disorientation, attraction and collision.

“Birds may starve when artificial lighting disrupts foraging, and fledgling seabirds may not be able to take their first flight if their nesting habitat never becomes dark,” the guidelines read.

Artificial light can disorient flying migratory birds, diverting from efficient migratory routes or even collide with infrastructure.

Migratory shorebirds may avoid roosting sites, which have high proportion of lights and increase their vulnerability to predation due to visibility.

Exposure to white light also causes stress hormone corticosterone to increase among free living songbirds, as against green or red light. The species may produce fewer offspring due to high stress hormone levels as a result.

Besides birds, other life forms such as mammals, reptiles and fish can also be affected by artificial light.

“Tammar wallabies (Macropus eugenii) exposed to artificial light have been shown to delay reproduction and clownfish (Amphiprion ocellaris) eggs incubated under constant light do not hatch,” the document added.

The hatchlings of marine turtles may be unable to find their way to the ocean if beaches are lit.

Among bats, roosting, emerging, foraging, swarming, mating, commuting, drinking and migrating is impacted.

The document also mentioned successful instances like the Gorgon Liquefied Natural Gas Plant on Barrow Island in the state of Western Australia. Here, lighting management was conducted to reduce skyglow and helped long-term marine turtle management.

Another example cited was that of migratory short-tailed shearwaters (Ardenna tenuirostris) on Phillip Island in Victoria, Australia.