O nce a year, Corvo, the smallest and most northerly island of Portugal’s Azores archipelago, goes dark. Since 2019, the island’s 450 or so inhabitants have chosen to switch off the lights every autumn for five nights to tackle the disastrous effects of artificial light on Cory’s shearwaters, a seabird endemic to the Atlantic Ocean.

It began in 1991 when the community noticed huge numbers of deaths among young shearwaters.

The juveniles spend three months in their nests before attempting their first flight to the ocean, orienting themselves by the stars.

A newborn Cory’s shearwater chick

Unfortunately, many are fatally confused by the artificial glow of streetlights, and end up crashing into Vila do Corvo’s narrow streets.

Local people began rescuing them at night, roaming through the village in the dark.…