How Do Birds Know to Fly South?
It is known that a few bird species leave their homes and fly south for the winter. This movement of birds which occurs according to the seasons each year is known as migration. Why do birds fly south for the winter? There are a few reasons why birds migrate.
Many bird species are unable to find food, such as insects or nectar, as the season changes. For example, bird species that feed only on insects in the north during the summer find a shortage of food in the fall. Thus, these birds need to move to a warmer location, mostly in the south, to find food.
Also, many species of birds breed in one place and spend their winters in another place. The regions where birds breed are known as breeding grounds. The regions where birds spend the winter are known as overwintering grounds. Therefore, migration is also important for birds to travel between breeding grounds and overwintering grounds.
How do birds know when to migrate? Birds can sense when it is getting colder and when there is a shortage of food supply. The timing of migration is also determined by the changes in the length of days, which get shorter in the winter.
Thus, when winter approaches, birds migrate in groups called flocks towards the warmer regions in the south. Usually, V-shaped groups of birds may be seen in the sky as they migrate from one region to another.
The bird which migrates the longest distance is the Arctic tern. Birds such as the Arctic tern use the Sun, the stars, and the Earth’s magnetic field to create mental maps to reach their location. How do birds know in which direction to fly?
Birds store deposits of a mineral called magnetite in their beaks. This mineral interacts with the Earth’s magnetic field. Furthermore, special proteins called cryptochromes are present in their eyes. These proteins interact with blue light, exciting molecules called flavins inside these proteins. Electrons in these flavins spin and act like tiny compasses in birds.
Thus, this is how birds migrate and know in which direction to fly. Watch this video to learn more about how birds know to fly south for the winter!