According to the Humane Society, birds do not hibernate. Birds deal with cold temperatures and dwindling food supply by flying to warmer regions during the winter months.
For many years, people believed that birds went into a hibernation state during the winter because they seemed to disappear every time the weather got cold. After performing studies and tracking the patterns of thousands of birds, migration was discovered. The birds fly south in the winter to help deal with the cold. They generally return to the same spot when the weather gets warm again. Most birds fly south to the same place every winter and come home to the same place every spring, although they will find new places to live and migrate to if their living conditions are compromised while they are away from either.
Most birds fly a great distance, often hundreds or thousands of miles, to get to their migration destination. Depending on the species of birds, the flight can be different lengths. Some female birds and young birds fly farther south than male birds because they are not as equipped as the males to deal with colder temperatures. Many bird species choose to only fly south during the evening hours and night hours because they can rest and feed on insects more easily during the daytime hours.