Many types of birds, such as geese, migrate just before colder weather arrives. Migration is a seasonal movement between breeding and non-breeding areas, often triggered by changing daylight, temperature, food supplies, and weather conditions.
Geese commonly fly south in autumn to reach places with more dependable food and open water. Their familiar V-shaped formations help reduce air resistance for birds following behind, while the lead position rotates as the flock travels. Different goose species use different routes, and some populations travel thousands of kilometres.
Migration is not simply a reaction to cold. Birds may begin moving before conditions become severe because natural cues and internal biological rhythms provide advance warning. Many species return north in spring, when longer days and abundant insects or plants make breeding more successful.
A common mix-up is confusing migration with hibernation. Migrating birds remain active and travel to another region; hibernating animals enter a prolonged state of reduced activity. Some birds also move only short distances, so migration does not always mean crossing continents.