Natural darkness has a conservation value in the same way that clean water, air and soil has intrinsic value. Artificial light at night is increasing globally by about two per cent per year (Kyba et al., 2017). Over the 25-year period 1992 – 2017 artificial light emissions increased by at least 49% (Sánchez de Miguel et al., 2021). Animals perceive light differently from humans and artificial light can disrupt critical behaviour and cause physiological changes in wildlife (Russart and Nelson, 2018; Sanders et al., 2021). For example, hatchling marine turtles may not be able to find the ocean when beaches are lit, and fledgling seabirds may not take their first flight if their nesting habitat never becomes dark (Witherington and Martin, 2003; Rodríguez et al., 2017c). 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 (Robert et al., 2015; Fobert et al., 2019).

Consequently, artificial light has the potential to stall the recovery of a threatened species. For migratory species, the impact of artificial light may compromise an animal’s ability to undertake long-distance migrations integral to its life cycle.

Artificial light at night provides for human safety, amenity and increased productivity. These Guidelines do not infringe on human safety obligations. Where there are competing objectives for lighting, creative solutions may be needed that meet both human safety requirements for artificial light and threatened and migratory species conservation.

The Guidelines outline the process to be followed where there is the potential for artificial lighting to affect wildlife. They apply to new projects, lighting upgrades (retrofitting) and where there is evidence of wildlife being affected by existing artificial light.