Process essay two - How do Birds Migrate?

Have you ever wonder why do birds migrate or where do they go during the season changes? This article will satisfy your curiosity.

Human beings migrate, but do you know birds migrate too? The process, motivation and the mechanism behind bird migration are much more complex than humans.

From the age of Ancient Greek to the modern and advanced society of 21st-century, the secret of bird migration has aroused people’s curiosity for over 3,000 years. How do birds fly over half of Earth? Why do they know where to fly without a compass? Many efforts have been made by ancient Greeks, Homer and Aristotle, as well as scientists for understanding one question: How do birds migrate? To put it simply, there are several main stages of migration: trigger, navigate and survive.

Before starting the migration, the birds need some triggers. Why do birds migrate? The answer can’t be simpler. We all need triggers to motivate us, don’t we? Then birds need theirs too. At the commencement, their ancestors were just looking for places to live. The main triggers of migration are needs of food sources and nesting locations. If birds don’t migrate, the massive competition for food in breeding seasons will make them starved and lack healthy offspring. Therefore, birds will observe the natural phenomenon to set the departure time. By counting the sunlight angle and the daylight duration, they will know whether it’s the season to take off. The triggering mechanism of migration seems reasonable and clear. Nevertheless, how exactly do the birds navigate and also know their travel direction? Here come the crucial stages of migration, navigate and survive.

We have been curious about the mechanism and the theory of bird navigation, but it’s still an enigma that how birds find and follow the routes. Because the process of migrating is a combination of complex factors, there are mainly three methods that scientists have discovered to navigate: magnetic sensing, geographic mapping and star orienting (see Picture1). Firstly, the reason why birds don’t need compasses to navigate is because they have built-in compasses. There are several kinds of birds have special compounds in their organs in order to sense the magnetic field of Earth, which helps them to find the right direction just like internal compasses. Another processes are the geographic mapping, and the star orienting. Because birds follow the same migration routes repeatedly, their sophisticated eyesight allows them to navigate in their journey. It’s just like marking landmarks on the route to keep in the right direction. In the day times, they will be rivers, coastlines and mountains; in the night times, they will be stars and the direction of sea breeze. Generally speaking, the mystery of bird navigation is certainly not as simple as we thought. Nonetheless, there are still some hazards and threats for birds to overcome despite having impressive navigating abilities.

Migration is the process that tests both the birds’ physical and mental capabilities, hence the survival issues surely can’t be ignored. During the process lasting for months, the poor weather, food shortage, skyscrapers, planes and even windows can be the threats killing birds (see picture 2). It’s estimated that more than 60 percent of some birds never survive a full migration. Therefore, what they take as the strategies are teamwork and preparation beforehand. From flying in a stamina –saving V-shape, travel together to survive the marauders, to taking turns to collect food for newborns and casualties (see Picture 3), birds work together to keep the best migrating-efficiency. They as well ingest and save fat which is up to double times as their weight for the long trip. In addition, if birds encounter predators and have casualties, they will not persist in deaths or loses but keep migrating to survive the threats. Survival issues are not really easy-doing works to birds.

To sum up, the secret of bird migration contains only three main stages, trigger, navigate and survive. They depart for their offspring; they navigate themselves properly; they prepare and work together to overcome the threats, aren’t birds impressive? birds are truly brilliant creatures. Don’t judge a book by its cover. The small brains of birds actually contain genuine knowledge and techniques from nature. No matter how well we know about birds or whether they can migrate successfully, the mysteries and charms of birds will keep lasting in our minds.

Pictures

Picture 1

Picture 2

Picture 3

Reference

Unknown authors (2007). The Basics of Bird Migration: How, Why, And Where. The Cornell Lab (2015). Retrieved from https://www.allaboutbirds.org/the-basics-how-why-and-where-of-bird-migration/

Melissa Mayntz (2018). Bird Migration - How It Works .The Spruce https://www.thespruce.com/how-birds-migrate-386445