CLEVELAND, Dec. 7 (UPI) -- Birds have a strong preference for nighttime migration, so much so that migratory birds caught over water at daybreak turn around for shore. Researchers discovered the phenomenon using radar normally reserved for tracking weather systems.
As the radar revealed, birds flying over the Great Lakes when the sun rises typically increase their elevation and turn back. Researchers suggest the elevation rise is an attempt to gauge the distance to the far side of the lake.