Have you wondered how those all the birds migrate? How do they prepare for it, how do they migrate without getting lost, how would they so accurately reach again back and many more questions are often coming when we think about migration. This article covers all these aspects and many more.
If you want to know what is bird migration, types of it, and want to have a complete guide on bird migration, check out this interesting article written by me.
How do birds prepare for migration?
Birds usually migrate in the winter season, and while preparing for the migration, the birds build up their body fat. They also fuel up themselves with food and reserve up to 50% of their body weight. The hormonal changes in the birds trigger a huge appetite, making them eat the food voraciously, which leads to energy gain. They eat grains, fruits and other food items that can be converted into body fat and used as energy.
Fats are considered an ideal way for the birds to store fats, and each one gram produces nine kilocalories of energy. It is considered better than the carbohydrate because it requires more energy to store and weighs more due to the water molecules. Weight is the major problem for the migrating birds as it is due to heavyweight the birds require more energy to fly high in the sky.
When the days are shortened during the summer’s end, photoreceptors in the bird’s brain trigger the hormonal changes, which molts the new feathers in the birds so that they can fly comfortably during their long journey.
How do birds migrate without getting lost?
Migrating birds normally travel 70,000 kilometers independently as they don’t have navigation maps like we use for travelling. The birds who migrate always know their native place and return correctly without getting lost. As per the view of the scientists, the birds who wish to migrate might follow some of the below ways or the combination of these.
Some birds observe the landscape features like the rivers, mountains, greenery and even the modes of transport.
Some birds have magnetite above their nostrils, which helps them travel with the earth’s magnetic field during their navigation. Magnetite are the magnetized rock that acts as a GPS unit for the pigeons.
They also take the help of the position of the stars, sun and the moon to find their way. But, most of them find their way back to their home accurately, and that’s why you might see the same bird in your yard every year.
Researchers have also found some specialized cells in the bird’s eye that can help them view the earth’s magnetic fields. With the help of these sensors, they can travel to areas where there are fewer landmarks like the ocean. So there are chances that the migratory birds might make use of both eyes sensors and magnetite beak to sense the directions while traveling to long distances that don’t have much landmarks such as the ocean.
Some birds learn migration from their parents, while the humans train some of those raised in captivity with the help of the plane. It is also observed that sometimes the navigating birds feel lost and end up going to the new location if they lose their internal sense of navigation or even if the weather is stormy. Such heavy winds might misguide them and force them to change their direction.
How do birds know direction?
Birds also use the navigational hints similar to the humans to travel from one place to another. As we observe the landmarks that are near the destination where we want to go, the birds also make use of the landmarks to check the direction during their migration journey. But they have an additional advantage of tracking the direction which is not helpful to us and that is the stars in the sky. Stars help them to figure out the region and accordingly they decide the direction where they want to go. Here are some of the ways through which they can get to know their location.
Smell – Birds make use of their nostrils known as nares to identify the direction. Their nostrils are connected to the beak and rest of the face. As per the research, the birds have the smell map that can identify the mix of smells of the particular location such as their home range. As per the scientists, if the birds don’t have a strong smell, they won’t navigate properly to the destination.
Landmarks – Just ashumans use natural landscapes to figure the direction, the birds use a similar way to identify the direction. In addition, they know how these landscape features are connected to the each other. For example, when the bird will fly from one building it will observe the second building and when it comes to the second building, it will observe the third building.
Celestial Cues – Just as the seafarers in the early days used to predict the directions with the help of stars, similarly the birds make use of the stars as a cue to make their migratory decisions. According to some scientists, the migratory birds observe the star patterns to identify the exact direction to reach their destination. Some birds also make use of other celestial bodies like the sun to identify the direction.
How do birds know when to migrate south?
As humans know that the sun rises in the east and sets in the west, similarly even the birds can figure out the direction of sunrise and sunset. Therefore the species of migratory birds who want to fly in the south for the winter season keep a track of the sun’s position in the sky throughout the day as their direction guide.
The birds also take help of the stars in the sky as their navigational guide. Also, traveling to South is as simple for them as they determine and observe the warm temperature of the south region while migrating.
The birds also try to identify the South direction by sensing the different directions and the magnetic field. Some of the birds also observe the mountains, nature and other things to determine the South direction.
According to some scientists, the birds can get some direction guidance from the Earth’s magnetic field. Some birds have a magnetite which is a magnetic material in their brain to determine the directions and fly towards the south.
Some bird also make their Southern region migration in short feeding hops, by moving to the reed beds and other popular areas on the south coast.
Do birds migrate to the same place? Every year?
Some birds return to the same local place or region where they have been in the previous year. Birds who travel to different places, usually have short lives, but if these birds come to the yard the next year again, then there are chances that these birds will live for many years.
During spring, the birds who have migrated come to the cooler regions to build their nest. These birds usually make an incredible journey during their migration period and then return back to their native place after a year.
Birds migrate to different places to survive during the summer or in winter as per the weather condition that suits their body temperature. Once they are comfortable at that place and feel safe they again migrate to that region even after the year.
Birds also observe the amount of food abundance in the migrated region so that can during their breeding season they can migrate to the place that has the best habitat and food for raising their young ones. Just as the food, water source is also the important factor for their living. So during the summer when the water bodies dries up they search for the regions where there is ample amount of water to satisfy their thirst.
How far can birds fly during migration?
During migration, the birds can travel up to 16,000 miles. They fly at the speed of 30mph, and with this speed, they can reach the destination in 533 hours. Thus, birds fly for 8 hours in a day to migrate to their destination, and it might take 66 days to reach there.
Most of the birds fly for 15- 55 miles per hour, but it varies from species to species. Migratory birds travel 15- 600 miles in a day. Depending on the species of the birds, the flying altitude depends. For example, songbirds travel at an altitude of 500-2000 feet, while the vultures and Geese fly at the altitude of 29,000-37,000 feet. Some scientists believe that these birds fly at high altitudes to save their energy with less flapping of wings and more by gliding. They move up and down in the sky to boost their natural lift due to the change in density.
Nowadays, flying high and at low altitudes is dangerous to the birds due to the skyscrapers or tall buildings built in the cities. These buildings usually come in the way of the migrating birds, which can lead to a collision if they are flying at a great speed.
Do birds migrate alone?
Some birds migrate alone, while some prefer flying in groups. During the migration period, they are always seen flying in flocks throughout their journey. Flocked bird migrants are usually seen during the day and are most familiar to us. In rare cases, the flocks of birds can be seen flying in small groups with their family where the adult birds make their younger ones aware of the flying routes.
As per the study, flying in groups help them to conserve only half of their energy, rather than flying alone. Each species of bird fly in different shape formations to save its energy. Songs birds are seen flying in swarm while some big birds like geese migrate in V shape formation. Birds can be seen flying in the V shape as it becomes easier for them to fly. The senior or their leader flies ahead of the birds, and other birds follow him through the migration.
Some bird species fly at night to avoid being attacked by their enemies. However, at night most of the birds rest in their nest and avoid flying, so some birds who are at the high risk of being attacked prefer at night to have a safe migration without worrying about the threats.
What problems do migrating birds face?
Different birds face different types of problems and risks during their migration process, as mentioned below.
Exhaustion: Birds can easily travel long distances without even taking a rest for a while. But some birds who wish to migrate or are migrating sometimes feel exhausted due to the extensive travelling they do to reach their destination. When these birds feel tired or drained out, it lowers their flying speed and affects their migration. They might also collide with some obstacles on their way.
Starvation: When the birds migrate, they need a lot of food to eat on their way, till they reach their destination place. Therefore, inadequate food supply might cause starvation in the migrating birds if they don’t get enough food supply. Habitat destruction might be one of the reasons for starvation, but it can also be possible if many flocks of birds are fed at the same time.
Predators: During the migration, predators are the major threat for the birds. They may get attacked if they are unaware of the local predators at their stop location. Cats and feral cats are the big threats for the migrating birds, but even the wild predators are similarly dangerous to the migrating birds.
Pollution: Pollution such as oil spills and lead poisoning can adversely affects the local birds and the migratory birds as well. Birds who have ingested toxins during their migration may suffer from poisonous effects after they leave the area. Also, heavy pollution may affect the habitat and reduce their chances of successful migration.
Natural Disasters: Hurricanes, Blizzards, Floods, wildfires, and other natural disasters might destroy the birds’ natural food sources in their resting spot. Also, some birds caught in these disasters get harmed like they can get an injury and sometimes have to face death. Trimming of their feathers in a wildfire or early winter blizzard are some of the reasons for their death.
Disease: When birds fly in flocks, the disease outbreak can be a devastating experience for such birds. This can be more dangerous when the infected bird carrying the disease land on the breeding grounds or in the densely populated regions in the winter.
Hunting: Sometimes, hunting seasons coincide with the migration period, which can be threatening to the birds. Illegal hunters are the actual threats for the birds but even the legitimate hunters can by mistakenly shoot the protected birds from the flight.
That’s all in this article.