In a tragic incident on October 4-5, nearly 1,000 birds lost their lives colliding with a brilliantly illuminated glass building in Chicago, shedding light on the alarming threat of light pollution. A groundbreaking study, recently published in Nature Communications, reveals that artificial light serves as a pivotal indicator of bird landing sites during migration, leading them into ecological traps in urban areas. Lead author Kyle Horton, an assistant professor at Colorado State University, emphasizes the urgent need to address this growing menace.
The study, the largest of its kind, employs weather radar data to map bird stopover density across the United States. It exposes the multifaceted risks that cities pose to migrating birds, from deadly collisions to diminished habitat and competition for resources in urban parks. Migration, an already perilous journey for birds covering hundreds to thousands of miles, becomes further challenging when suitable rest stops are compromised.
“These stopover locations are the fuelling stations,” explains Horton, emphasizing their crucial role in sustaining birds during migration. The study provides continent-wide maps of migration stopover hotspots, offering insights essential for conservation planning.
Light pollution emerges as the second-highest predictor of stopover density, following elevation. The dilemma arises – should urban centres be conserved as vital stopover locations or targeted for lights-out campaigns? Horton and his colleagues are navigating this complexity, collaborating with nonprofit and government organizations to find a balanced solution.
The societal challenge of urban lighting complicates matters, as stakeholders resist turning off lights due to aesthetics and social pressures. However, solutions like Bird Cast offer hope, providing migration forecasts and real-time maps to aid in reducing light pollution. Retrofitting windows with bird-friendly decals and adjusting light brightness and colour are practical steps to mitigate collisions.
The casualties at McCormick Place Convention Centre underscore the urgency of action. Mass fatalities involving over 100 birds are tragically common, with an estimated one billion bird-building collisions in the U.S. annually. Public awareness becomes a crucial tool in the fight against light pollution, with Horton emphasizing the immediate positive impact of a collective switch-off.