Study Finds Severe Space Weather Causes 20% Decrease in Migratory Bird Populations, Impacts Other Species

Severe space weather events have been linked to a 9-17% reduction in migrating bird populations, both in the spring and fall, according to a recent study. These events, such as solar flares and energetic outbursts, disrupt Earth’s magnetic field, which migratory birds rely on for navigation. The study, conducted by researchers from the University of Michigan, analyzed a 23-year dataset of bird migration across the Great Plains, a major migratory corridor. They found that birds migrating during space weather events had more difficulty navigating, particularly under overcast conditions in the fall. The researchers used radar images collected at 37 stations in the Great Plains to estimate migration intensity and flight direction. The dataset included 1.7 million radar scans from the fall and 1.4 million from the spring. The team also matched the radar data with a geomagnetic disturbance index, which represented the maximum hourly change in magnetic conditions. Statistical models were used to measure the effects of magnetic disturbances on bird migration. In addition to the reduction in numbers, the researchers observed that birds appeared to drift with the wind more frequently during geomagnetic disturbances in the fall. This suggests that a combination of obscured celestial cues and magnetic disruption may hinder navigation. The study highlights how animal decisions are influenced by environmental conditions, including those that are imperceptible to humans, and how these decisions impact population-level patterns of animal movement.