Fat for fuel
in order to further cognitive strength migratory animals, let’s do a comparison. Long-distance runners weigh about 65 kilograms and need to run 42 kilometers to complete a marathon; Canadian geese weigh 6.5 kilograms and have a migratory distance of 966 kilometers. Calculated in proportion to body weight, the migration of the Canadian geese is equivalent to a marathon runner’s long-distance run of 9660 kilometers-that is, the distance of 230 marathons.
For such a high-intensity trip, it is necessary to prepare sufficient energy. Many migratory birds will eat a lot before they travel far, storing excess energy in the subcutaneous lipid membrane, and their weight has increased a lot compared to usual. For example, hummingbirds will double their weight before migrating. Weight is very important at this time. Just imagine which thin and poor bird can afford such a high-intensity task? Fat supports the entire journey like fuel. For example, for a bird weighing 15 grams, each gram of fat can support a flight of 200 kilometers. In addition, fruits contain a lot of sugar, which is easier to convert into fat than insects. Some migratory birds usually feed on insects, but in order to migrate, many birds change their diets to increase fat. For example, the thrush will take berries and other fruits as its staple food before setting off.
Imagine a pregnant mother who has to run a long-distance marathon and give birth and nurse her children without eating or drinking… This is absolutely impossible in human society. Let’s take a look at the wonderful world of gray whales. In summer, the Arctic Ocean has 24 hours of sunshine. The seawater is rich in nutrients and food. Gray whales seize this opportunity. They fill themselves with tons of krill and grow a thick layer on their bodies. Thick fat. At the beginning of October, the daylight began to shorten, the amount of sunlight began to decrease, and the nutrient content of the seawater decreased. At this time, it was time for the gray whale to set off to the south. The entire migration distance from the Arctic Ocean to the Gulf of Mexico was 20,000 kilometers back and forth. Pregnant female whales must complete this journey, otherwise their baby whales will not be able to survive in the cold waters near the Arctic, and male gray whales and unconceived gray whales must also migrate south for mating.
The whale’s journey to the south took about two months. During this period, they hardly eat or drink. Even after arriving at the destination and giving birth to their baby whales, the female whales still eat very little. Most of the fat, even the milk that feeds baby whales, is fat. By spring, they began to return to the north. At this time, there is not much fat left on them, and some old and young whales will die on the way back. When the supported gray whales returned to their home in the north (at this time, they had not eaten for almost 7 months), their weight had been reduced by 1/3, and at this time, they could finally eat! They filter amphipods and krill with their own whiskers. This is their first meal after a 7-month journey of 20,000 kilometers or more!
Take a ride on the wind
In order to fly back to their hometown, the animals really tried all kinds of tricks. For example, the black-cheeked warbler, which is only 10 cm in length, can migrate from the southeastern part of the United States to South America in just five days! Before setting off, they have been waiting. When the violent northwest wind arrives, they will ride a “hitch” and use the power of the wind to cross the vast Atlantic Ocean to South America. However, even with the help of the wind, during the migration of the black-cheeked warbler, they need to flap their wings about 4 million times to reach the end. Some birds, such as falcons, eagles, pelicans, and cranes, have their wings spread out and wide, so they don’t need to flap their wings, they only need to spread their wings and tails, and they can fly on the rising heat. The warm air flow is warm air rising from the ground or water surface. The air flow rises because of heat or obstacles such as mountains. When the birds migrate along the mountains, the heating flow is like an elevator, helping the birds flying upward in a spiral to save energy; when the heating flow cools down and stops rising, the birds only need to flap their wings to quickly Move into the next warm air flow and continue to rise and move forward with the help of the next “elevator”. In this way, the bird can fly over hundreds of kilometers in a day with very little energy consumption. Because the heating flow is easier to form over the land, soaring birds will try to migrate over the land as much as possible. They would rather go around a long distance to avoid the waterway and get on the effort-saving “elevator”. The birds on the seashore can even fly all day long. The wind blows through the sea surface, and the closer it is to the sea surface, the more friction it will be, resulting in many slices in the air layer about 45 meters high, and the wind speed can reach the highest speed from the lowest zero point to the topmost layer. The birds on the seaside make full use of this to hover, rise and fall in the air currents, looking for the position with the highest wind speed in the sky to get the maximum power support. Therefore, such shots will often appear in documentaries, on the vast sea, The bird hovered and flew majesticly on the sea, relaxed and free, effortlessly.
With animals this “vehicle”
in addition to wind and air, some animals have become free of other animal migration “vehicle.” Flower mites feed on nectar and pollen, and they rely on hummingbirds to migrate to new plants. When a hummingbird sucks nectar from a flower, the flower mites can get into the hummingbird’s nose in less than 1 second; when the hummingbird gets near another flower, the flower mites get out again. While the hummingbird is sniffing the flower, the flower mites will jump out quickly to decide whether to “get off” from the hummingbird’s nose.
Day road night road, do not take the unusual way
you must have seen a large group of birds flying from the sky during the day, that you have not inadvertently glimpsed the shadow of a cloud of dense mass of passing the moon? Yes, that is the flock of birds flying at night. Relatively speaking, most migratory birds, especially small insectivorous birds, grain-eaters, waders and ducks, eat and rest during the day, and fly at night. Therefore, one way to count the number of migratory birds is to observe and count under the moon. The shadow of the flock of birds (in the migratory season, within an hour, people who observe the moon can see up to 200 species of birds). These birds fly at night to avoid the predators, birds of prey, etc. they will encounter during the day, and actively miss the chance to meet them. However, some scientists believe that a cool, windless night is more suitable for small birds to fly. At night, birds can clearly recognize the contours of the ground with the light of the moon, the reflection of clouds, the twinkle of stars and the reflection of the water surface. In addition, the fixed-position Polaris can also guide them north. When flying, the flocks of birds gather into a whole through their calls to convey each other’s information. However, if the night is dark, dense clouds or storms, the birds will stop and escape the night. And those large birds and raptors, such as cranes, storks, eagles, falcons and crows, are less threatened by predators and can fly swaggeringly during the day. And some birds, such as wild ducks, geese, swans, etc., fly both day and night.
During the 2000 Sydney Olympics, an army of millions of Bogon moths on their way invaded a stadium. Scientists believe that these panicking gray-brown moths were confused by the bright lights of the stadium. These moths rely on moonlight to navigate while migrating, and they may mistake the lights for moonlight.
Birds choose to fly in the sky during the day or night, and fish will also find special channels when migrating. In the Bermuda Triangle, the legendary place where planes and ships will mysteriously disappear is connected to a sea area called the Sargasso Sea, where young European eels live, and they look as delicate as transparent ribbons. They start from the Sargasso Sea, go upstream to European lakes and rivers, and then return to the sea to mate after maturity. Fortunately, the current can help them cross the Atlantic Ocean. Even so, it takes three years for them to reach the freshwater areas of Europe. The newly hatched baby eels are like rolled leaves, and begin their journey to Europe with the ocean currents. When they reach the coast, they have grown into small glass eels, and they must migrate upstream to the brackish water area of the estuary, and then reach streams or small rivers with freshwater environments.
Eels need to swim hundreds of kilometers upstream, and they have a knack for this. The skin of eels is very thick, covered with scales, and their gill holes are also very narrow. This physical feature ensures that they can breathe on wet ground. In the night after the rain, the plants are covered with dew, and the eel twists its body like a snake through the slippery grass, and can even crawl for thousands of meters. If the water embankment is covered by turf, the eel’s crawling is easier . As they slide upstream, the eels will gather together in hundreds of thousands, cross each other’s bodies and crawl forward. After the eels arrive at their new homes—that is, freshwater rivers, lakes, or ponds, they will live there for 6 to 20 years, and they will grow to 1.5 meters long, when they are already very mature. They always hide during the day and are active at night. In a certain summer, some eels will migrate to the ocean collectively as if they receive some kind of signal.
Fat for fuel