Mid-September 2025 is proving to be a remarkable time for bird enthusiasts in Tennessee, as the state experiences a massive nocturnal bird migration event. According to forecasts from the Cornell Lab of Ornithology and Colorado State University, an estimated 387.8 million birds were airborne across the United States at 1:20 a.m. ET on September 15. This extraordinary surge in migratory activity is so vast that it is even detectable on weather radar systems.