Birds migrate to mate, search for food, escape harsh weather, evade predators and to flee from diseases. Birds also migrate to raise their young in a safe environment.
Birds migrate when food is scarce. Birds that stay in a single area consume much of the food sources in a particular area, forcing them to flock north to places where there is more food. When food dwindles in the fall, they flock back to warmer conditions where food is more abundant.
Birds normally look for adequate shelter, safety, food and proper breeding grounds when nurturing young. However, adult birds mostly choose such locations for the sake of migrating back to a certain region on their own, and young birds are left to migrate alone when capable.
Laying eggs in hot temperatures can be dangerous for the chicks, which is why birds flock north. Birds that live in the Arctic also move to warmer areas when the temperature falls.
Birds help their offspring survive by escaping to places where predators are not as frequent. They may also stay away from places with plentiful food because more predators may be present. Adults also move to other places to escape diseases that may spread within colonies. Moving to another spot lessens the chance of spreading illnesses to newborn chicks.