Seeing the marks in his math exam paper, Butun felt disheartened. He had barely passed. Why does such a bad day have to come in life, he wondered. He scored very well in other subjects, but only math let him down.
Butun’s math teacher is very strict. She handed him the paper and scolded him, saying, “Since it was the term exam, I gave a bit more marks, you’re lucky to have passed. However, you have a lot of trouble coming your way in the finals.” With a heavy heart, Butun didn’t go out to play in the evening. He walked aimlessly around the roof of his house with a broken spirit.
There are many flowering plants in Butun's house. A small bird flew from the marigold plant and landed on the roof's cornice. From there, it flew up into the sky. In the evening, the birds return home. By home, he means a giant banyan tree, about 200 meters from Butun's house. The tree's tangled crown can be clearly seen from his house. Birds of all kinds fly around the tree, and not only can they be seen, but their chattering is also heard continuously. The huge tree is almost as tall as a five- or six-story building. The little bird, where did it fly? Its throat was very strangely colored. Butun had never seen such a bird on their roof before. Despite looking around, Butun couldn't find it. He thought, maybe the bird had hidden itself on a dark branch of a mango tree.
While gazing at the sky, Butun's eyes fell upon a group of herons flying by. Not exactly herons, but a little different.
As the flock of birds flies away, three more flocks follow in quick succession in the same direction. The red and yellow hues of the setting sun are blending into the birds' bright white wings. They are flying much higher than the birds whose chattering can be heard from the top of the banyan tree.
While watching the birds, Butun forgets about his math exam paper. He walks down the stairs and finds his father sitting on the sofa in the living room. The moment he sees his father, he remembers the math paper. Now, the birds fade from his mind.
"Didn't you go out to play today, Butun?" his father asks.
"No... I mean, I didn't feel like it."
"Hmm, sit here. It's getting cold now. In the evening, it’s better not to go to the roof and catch a chill. How is your studying going?"
It seemed as though his father couldn't avoid bringing up this unpleasant topic. However, Butun’s father never scolds him about his exam results. His mother's face just gets a little heavy. Today, she came into the living room with a cup of tea, set it down in front of his father, and said, "Butun's class teacher, Dipika Ma'am, called. She said that even though Butun did well in all subjects, he only barely passed in math."
Taking a sip of tea, Butun’s father replied, "It's okay. We need to manage one thing, right? He'll be fine."
To change the subject, Butun asks his father, "Dad, where do the birds flying far in the sky go?"
"It depends on how high they fly. The ones that fly below return to homes nearby, but the ones that fly very high are migratory birds. They come to our country from far away."
Now that winter has come, the birds that fly here are Siberian cranes, flamingos, pelicans... those kinds of birds."
"How do they know the way to fly from other countries every year?"
Butun's father put his cup of tea down and said, "That's the real question. It might seem like they have some sort of GPS in their heads. These migratory birds travel thousands of miles. For example, the cranes that fly from Siberia during winter travel almost 4,000 miles. Most migratory animals can fly non-stop for thirty hours. How these birds know the right path from such a long distance and reach the right place is truly a wonder. And their migration is, of course, a natural phenomenon."
"You've seen the GPS on the dashboard in our car. When we need to go somewhere on an unknown road, we use the GPS to get to the right place. Birds have a similar GPS-like system in their bodies, which helps them navigate without any trouble. However, what I just said wasn't easily discovered by scientists. It took many tests and experiments to figure it out. Even now, there’s still a lot of uncertainty about this."
"Where do the birds come from in our country, Dad?"
"They mainly come from very cold places. No matter how much we shiver during winter here, the temperature is just a small change for the migratory birds. For instance, it gets extremely cold in Siberia during winter. All the water freezes, and the temperature drops well below zero. Where will they find water there? That's why they fly to our country. They come every year. Then, when it starts to get hot here, the migratory birds fly back to their homeland. It's kind of like how we all go on vacation during Christmas break; the birds go on their vacation too. But there’s a difference. What's that? In places where the temperature is very low, migratory birds lay eggs during the warmer months. The eggs hatch, and the chicks are raised by their parents. Before the whole area gets covered in ice, the birds take their chicks and fly to another country where the temperature is comparatively warmer. As soon as the weather starts getting warm here, the birds return to their cold homeland with their chicks."
"So how do they know the way? They don’t have GPS in their bodies!" Butun says, amazed.
"Who said they don’t? They absolutely do. Of course, they don’t have electronic devices like our cars, I don't need to tell you that. First, you need to understand a bit about GPS. GPS stands for 'Global Positioning System.'"
"Through satellites and electronic devices, we can know where we are at a specific time and find out the location of the place we want to go, and then head towards it."
To find directions, a compass is used. The Earth has a magnetic field, as you’ve read in your science book. One side has the North Pole, and the other has the South. Sailors used to navigate the seas with the help of a compass. This discovery was made almost a thousand years ago. After that, science advanced a lot. With thoughtful reasoning, using a compass, and doing calculations, there was no longer a need for manual direction-finding. With the help of electronic devices, finding directions has become much easier.
Now, coming to birds. They, too, without needing to do any calculations, sense the Earth's magnetic field and can determine the direction. This is their natural instinct. Just as airplanes take off, find the right direction, and fly, and then land at the right place, birds, too, understand the Earth's magnetic field and reach their destination in the same way."
Butun asks a simple question: "Then where do their GPS systems get installed?"
"Most likely, their beaks contain the GPS, and their eyes have a compass. In these two areas, animal experts have found magnetic particles (like magnetite) that help the birds sense direction. With their eyes, these birds can also recognize certain landmarks. Birds' vision is about eight times stronger than human eyes. Migratory birds can even mark big trees, houses, or hills as reference points. But it's not just migratory birds that have the ability to sense the Earth's magnetic field. Even common birds like pigeons and sparrows can find their homes using this special navigational ability."
Butun opens his eyes wide and says, "Pigeons used to carry letters and fly them to people's hands. I’ve read about it in books. So their GPS must be really powerful!"
His father nods in agreement, "Definitely powerful. That’s why pet pigeons always return home after flying all day. They were great at delivering letters without ever getting lost."
Butun asks, “Do the baby birds ever get lost during their migration?”
Butun’s father laughs and says, “Everyone worries about their babies, whether they're birds or humans! Like how your mom puts you on the bus in the morning so you don’t get lost. But when you grow up a bit, you’ll get on the school bus all by yourself, and she won’t need to worry about it. When birds bring their babies from cold countries, they train them on how to find their way and how to protect themselves from danger. When it’s time to return, the babies sometimes fly separately and join their parents again, meaning they’ve grown up quite a bit.”
“But Dad, what kind of danger can there be up so high in the sky?”
"Eagles might swoop down and catch them to eat, or they might crash into an airplane flying up from the ground. If they get hungry or thirsty or become tired from flying, they need to land. On the ground or in the water, many predators could catch and eat them..."
"So that’s why they stay in groups, Dad?"
"Exactly. A group means unity. Being together in happiness or danger is beneficial. If one bird gets sick, the whole flock will land together in a safe place."
Butun’s mind is filled with questions, “What if we had GPS in our bodies, how fun would that be, Dad!”
“Well, maybe we’ve lost that ability… but scientists claim that millions of years ago, humans spread out from Africa across the Earth. They would travel from one place to another in search of food and water. It was natural for them to navigate using the stars in the sky and the Earth's magnetic field. As humans became more detached from nature, they lost those natural instincts.”
"Okay, enough of the stories for now. I need to rest. One day, we should visit a bird sanctuary and see migratory birds up close. If you do well in math, maybe we can go after your final exam."
Hoping to see the birds up close, Butun decides he will do all his math homework right away. If birds can navigate from one country to another, surely getting a good result in math will be easy for him!
