Tuesday December 7, 2021

Hakai Magazine

Scientists have known since the 1970s that artificial lights at night pose a problem for seabirds. Trapped in the glow of bright lights shining from streetlights, cars, and buildings close to their breeding colonies, disoriented seabirds fly around until they fall to the ground exhausted, a phenomenon known as grounding. But new research led by Peter Ryan, an ornithologist at the University of Cape Town in South Africa, shows that far out at sea, the light from passing ships can have a similar, sometimes deadly, effect.

Previous research by Ryan in the 1980s showed that spotlights on the deck of a lobster boat in the Tristan da Cunha archipelago, in the remote southern Atlantic Ocean, were grounding hundreds of seabirds on deck each night. Fishers on the vessel—the only large ship in the region’s rock lobster fishery—attempted to curb the groundings by using fewer lights on deck and shielding cabin lights with heavy drapes. More than 20 years later, Ryan and his colleagues set out to determine if these mitigation measures undertaken by the Tristan rock lobster fishery were effective. Unfortunately, Ryan and his colleagues’ new study shows that though these mitigation measures have had an effect, even this reduced light is grounding large numbers of birds.


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