birds and light pollution -- 2/28/23
Today's selection -- from An Immense World by Ed Yong. The plight of light pollution and the added impact on birds:
"In 2001, when astronomer Pierantonio Cinzano and his colleagues created the first global atlas of light pollution, they calculated that two-thirds of the world's population lived in light-polluted areas, where the nights were at least 10 percent brighter than natural darkness. Around 40 percent of humankind is permanently bathed in the equivalent of perpetual moonlight, and around 25 percent constantly experiences an artificial twilight that exceeds the full moon. '"Night" never really comes for them,' the researchers wrote.
"In 2016, when the team updated their atlas, they found that the problem was even worse. By then, around 83 percent of people -- and more than 99 percent of Americans and Europeans -- were living under light-polluted skies. Every year, the proportion of the planet covered by artificial light gets 2 percent bigger and 2 percent brighter. A luminous fog now smothers a quarter of Earth's surface and is thick enough in many places to blot out the stars. Over a third of humanity, and almost 80 percent of North Americans, can no longer see the Milky Way. 'The thought of light traveling billions of years from distant galaxies only to be washed out in the last billionth of a second by the glow from the nearest strip mall depresses me no end,' vision scientist Sonke Johnsen once wrote.
"At Colter Bay, Cole flips the lights back to white, and I wince. The extra illumination feels harsh and unpleasant. The Milky Way seems fainter now, and consequently, the world feels smaller. Sensory pollution is the pollution of disconnection. It detaches us from the cosmos. It drowns out the stimuli that link animals to their surroundings and to each other. In making the planet brighter and louder, we have also fragmented it. While razing rainforests and bleaching coral reefs, we have also endangered sensory environments. That must now change. We have to save the quiet, and preserve the dark.
"Every year, on September 11, the sky above New York City is pierced by two columns of intense blue light. This annual art installation, known as Tribute in Light, commemorates the terrorist attacks of 2001, with the ascending beams standing in for the fallen Twin Towers. Each is produced by 44 xenon bulbs with 7,000-watt intensities. Their light can be seen from 60 miles away. From closer up, onlookers often notice small flecks, dancing amid the beams like gentle flurries of snow. Those flecks are birds. Thousands of them.
"This annual ritual unfortunately occurs within the autumn migratory season, when billions of small songbirds undergo long flights through North American skies. Navigating under cover of darkness, they fly in such large numbers that they show up on radar. And by analyzing radar images, Benjamin van Doren showed that the Tribute in Light, across seven nights of operation, waylaid around 1.1 million birds. The beams reach so high that even at altitudes of several miles, passing birds are drawn into them. Warblers and other small species congregate within the light at densities up to 150 times their normal levels. They circle slowly, as if trapped within an incorporeal cage. They call frequently and intensely. They occasionally crash into nearby buildings.
"Migrations are grueling affairs that push small birds to their physiological limit. Even a nightlong detour could prematurely sap their energy reserves to fatal effect. So whenever a thousand birds or more are caught within the Tribute in Light, the bulbs are turned off for 20 minutes to let them regain their bearing. But that's just one source of light among many, and though intense and vertical, it only shines once a year. At other times, light pours out of sports stadia and tourist attractions, oil rigs and office buildings. It pushes back the dark and pulls in migrating birds. In 1886, shortly after Edison commercialized the electric lightbulb, nearly 1,000 birds died after colliding with an electrically illuminated tower in Decatur, Illinois. Over a century later, environmental scientist Travis Longcore and his colleagues calculated that almost 7 million birds a year die in the United States and Canada after flying into communication towers. The red lights of those towers are meant to warn aircraft pilots, but they also disrupt the orientation of nocturnal avian fliers, which then veer into wires or each other. Many of these deaths could be avoided simply by replacing steady lights with blinking ones."