ANIMALS – Bird migration is seasonal and occurs between their breeding grounds and their wintering grounds. Their primary motivation seems to be the search for optimal conditions for feeding and raising their young.
When spring sets in across the temperate regions of the Northern Hemisphere, the days lengthen, flowers bloom, and birds court, build nests, and raise their young. Many of these birds have been away all winter, spending the cold season further south to enjoy warmer weather. Some have traveled thousands of miles to reach their breeding grounds at the same time as in previous years. The reason they undertake such a journey is easy to understand: they seek to improve their chances of survival by escaping winter and heading south, where food is plentiful. Then they return north to raise their young in areas where they will have a better chance of survival: there are relatively few predators and the days are longer, giving parents more time to feed their young.
The origins of these annual journeys, however, are a matter of debate among scientists. The fossil record does not allow us to determine when the first birds began to migrate, but evidence suggests that this behavior is at least 125,000 years old. Genetic studies of the migrating birds (…) - 20minutes
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