Why do birds migrate?
Birds migrate seasonally to meet their needs of food, shelter, favorable environment, etc.
Birds are one such species of nature to whom migration is tantamount to survival. On close observation, one would find that birds are equipped with body parts, which are most apposite to the function of migration. They possess an excellent respiratory system and are exceptional navigators, due to which they can travel for long and renew their energy spent through some good respiration. Their ultra-light bones help them in taking flight easily and staying in the air for longer periods without much stoppage. Moreover, they have a brilliant heat insulation mechanism in place, which allows them to regulate their body temperature according to the climate that they’re flying into.
Out of a number of reasons for them migrating, food is the first and foremost. Birds have to go out in search of food, in various parts of the world due to seasonal changes and other contributing factors. Cultivations cannot stay the same throughout a year. As a result, lands often grow barren. Little insects that thrive on such cultivations, wear out of a region like this. In such an event, it becomes difficult for birds to stay put and wait out the barren period. Naturally, the next logical option would be to migrate to a place that has food in abundance, which they inevitably opt for.
Like humans, birds too survive on the basic necessities of food and shelter. Apart from migrating for food, birds have to migrate for a congenial environment as well. Many places on earth such as the tundra region and the tropical region are prone to extreme heat and cold conditions. This makes survival uneasy. Which is why, birds choose to migrate for the time when climate surrounding a particular region is unfavorable, and return once everything is in order again.
Another reason why birds migrate is breeding. Some birds breed at a specific time of the year. They usually look for places that are rich and abundant in food and climate, to raise their young ones in. Such places are normally inundated by bird colonies, which give birds the option of raising their young ones in a habitat that enables them to feel safe and learn ways of survival, quickly and efficiently.
Besides factors such as food and shelter, a number of other reasons play a major part, as to why birds migrate. Sometimes, birds migrate to secure themselves from the breakout of diseases or parasites, resulting from many birds and bird families living together for a long time. Largely, birds are potential preys for several predators. Birds therefore, choose to migrate away from these dangerous predators, in order to fend off from them.
Many a time, birds face some stiff competition while gathering food and other things, which are essential to their survival. Birds that are big and strong, do put up a fight against their competitors, and simply because they can afford to do so. Whereas, birds that lack in built are left no option, but to migrate and look for food in their new habitat. Some birds also have the practice of looking for food elsewhere, instead of the place where they've actually built their nest. So, in order to collect food, these birds migrate for a short while to the place of their choice, and return with food and other collectibles.
Hence, birds migrate for quite a number of reasons, but their main reason has been survival, always.