The increase in nighttime illumination through streetlights, ornamental lighting, and vehicles has affected the movement of the dung beetle.
Light pollution has affected birds, animals, and insects as much as other forms of pollution. As nighttime turns brighter, light affects nocturnal creatures the most.
The night lights are reflected back to earth and are seen as a sky glow by observers on earth. This omnipresent veil of light blocks out natural light from stars at night. This is compounded by particles in the air that increase the reflection.
The most affected creatures are those that use the sky for navigation during nighttime. The nocturnal dung beetle is one insect that uses its night vision to help them move across the nightscape.
An experiment comparing the migration of the Scarabaeus satyrus under clear skies and skies affected by bright light threw up some interesting findings. The dung beetles were studied in a rural setting of Limpopo province and in an urban area in inner Johannesburg.
It was apparent that the dung beetles exposed both to direct light and even sky glow were affected and had to change their strategy for migration. They abandon the Milky Way as their guidance system and instead rely on artificial light on the ground as beacons. But this strategic change has its consequences.
Light Pollution Comes At A High Cost For The Dung Beetles
Dung beetles make a ball of animal dung and roll it away from the pile to ward off competition. They use their inner compass to move away quickly, following a straight path.
This brief journey to their lair is preceded by a survey that resembled a dance. The survey helps identify landmarks along the course. As it follows unfamiliar routes each time during the night, the stars are the most dependable reference points. They use the Milky Way during starlit nights as their main reference point.
While the dung beetles roll in a different direction using natural light, sky glow or artificial light force them to all roll in one direction. They invariably end up in concretized land where they are unable to burrow into the ground.
Like the dung beetles, migratory birds are also affected during their long journey by artificial lights that affect their finely tuned navigation system. They even run the risk of losing their way.