The public is urged to turn off unnecessary lights during the day of the day, as nearly 43 million migrating birds are expected to fly over the state. This is believed to reduce disorientation and potentially fatal window collisions. The Purdue University's AeroEco Lab, which studies bird migration, predicts that 42.9 million birds will fly over Minnesota, with nearly 28,000 expected to pass over Minneapolis, 25,000 more than St. Paul and 20,000 over Rochester. The public is encouraged to keep turning off their lights during this period.