Why do swallows fly low on rainy days?

The reason why swallows fly low on rainy days

According to popular science books, the humidity in the air before it rains makes the wings of insects wetter. Therefore, the ability of the insects to fly as food for swallows is greatly affected. They can only fly close to the ground, so swallows also He lowered his flight altitude and looked for his own food—insects—close to the ground.

According to textual research, insects are the first animals on the earth to get rid of gravity and learn to fly. Due to millions of years of evolution, the safety performance of insects flying is extremely high, but why do insects lower their flying height when it is cloudy? Is it really caused by the high humidity in the air before it rains? Insect flying tools really look like people imagine So backward, can its wings be wet by humid air?

According to my comparison of the humidity of the air before rain and the humidity of a sunny day, I found that the difference is not very large. Moreover, it does not mean that the humidity in the air before rain must be greater than the humidity in a sunny day. Sometimes the humidity in the air is different. Sunny days are also very high and cause extreme sultry heat, but at this time the swallows in the sky do not fly very low. It can be seen that the influence of humidity in the air on the ability of insects to fly is not as great as people imagine.

The evolution of nature has made the wings of most insects have their own waterproof measures. These waterproof measures have a high degree of reliability and practicability, so that the wings of insects generally will not stick to the mist, let alone be affected by humid air. wet. Insects must have the ability to maintain flight ability in various humidity climates to ensure their survival in the cruel natural environment. Just imagine, if the flying ability of that kind of insects is greatly affected in the humid air, they will definitely be swept away by their natural enemies, and they will definitely not live today. Therefore, there should be other reasons why swallows and insects lower their flying height in cloudy days.

In the process of biological evolution, it must be reasonable for organisms to have a certain instinct, otherwise there is no need to evolve this instinct. The choice of biological evolution is often the most scientific choice. The author believes that swallows and insects choose to lower their flying altitude when it is cloudy to prevent damage from thunder and lightning, rain and hail.

Powerful lightning is enough to knock down a huge airplane, and small swallows and insects can’t resist the thunder and lightning, rain and hail. In history, a large number of birds and insects must have been killed by lightning and raindrops and hail in nature. So, after millions of years of evolution, today’s swallows and insects have a feeling of whether there will be thunder and lightning, raindrops and hail. Whenever it rains, in order to prevent it, as long as there is a little possibility of raindrops, hail and thunder, they will lower their flying heights and move near the ground that is convenient for timely avoidance to avoid becoming raindrops in the sky. , Hail and lightning strikes.

Therefore, insects are not unable to fly high in humid air, but in order to prevent rain, hail and lightning from hurting themselves, they instinctively lower their flying height before it rains. Insects that can’t fly as soon as they encounter humid air, even if they have appeared in history, they have long been eliminated by nature. In fact, the real flying masters on earth are all kinds of flying insects, not humans. Humans are not qualified to question the ability of insects to fly in humid air.

Swallow’s appearance characteristics

A collective name for 74 species of birds of the passeriformes (Hirundinidae) family. A few species are commonly known as Martin Yan. The body is small and light, with blue-black feathers, shiny, black and brown front chest, milky white abdomen; both wings are pointed and long, and the tail is forked like open scissors; the mouth is flat and short, the mouth is very deep; the flying speed is fast, Prey on mosquitoes, flies, locusts and other pests during the flight; and constantly emit sharp and short calls.

Concave tail, short bill, weak feet. Feathers are monochromatic, or have metallic blue or green; most species are similar in both sexes.

Swallows are a genus of passerine swallow family. This is a bird, small in size, 13-18 cm in length. The wing has a long tip and a fork-shaped tail. The back feathers are mostly grayish-blue-black, so in ancient times, it was called the black bird. The wings are long and easy to fly, the mouth is short and weak, and the mouth is wide, which is the mouth shape of a typical insectivorous bird. The feet are short and the claws are strong. There are more than 20 species of house swallows, rock swallows, grey sand swallows, golden waist swallows and hairy foot swallows in the world. There are 4 species in China, among which house swallows and golden waist swallows are more common.

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