Why do swallows fly low?

Swallow low flying snake aisle

The heavy rain is coming soon!

The working people in ancient China summed up many proverbs related to weather changes through their observation of daily life, such as swallows flying low, which were considered as a sign of rain.

The popular science book says that before it rains, the humidity in the air is high, which makes the wings of insects wet. Therefore, the flying ability of those insects as swallow food is greatly affected, and they can only fly near the ground. So the swallows also lowered their flying height and looked for their own food-insects near the ground.

According to research, insects are the earliest animals on earth to get rid of gravity and learn to fly. Due to millions of years of evolution, the safety performance of insect flight is extremely high, but why do insects reduce their flying height on cloudy days? Is it really caused by high air humidity before it rains? Insect flying tools are really as backward as people think. Will their wings get wet by humid air?

According to my comparison between the air humidity before rain and the humidity on sunny days, I found that the difference is not very big. And it doesn't mean that the humidity in the air must be higher than that in sunny days before it rains. Sometimes the humidity in the air is very high on sunny days, causing extremely sultry weather, but at this time the swallows in the sky are not flying very low. It can be seen that the influence of humidity in the air on insect flight ability is not as great as people think.

Natural evolution makes most insect wings have their own waterproof measures, which are highly reliable and practical, so that insect wings generally do not stick to fog, and they will not get wet by humid air. Insects must have the ability to keep flying in various humid climates in order to ensure their survival in the cruel natural environment. Imagine that if the flying ability of that kind of insect is greatly affected in humid air, they will definitely be swept away by natural enemies and will never live today. So swallows and insects should lower their flying height on cloudy days, and there are other reasons.

In the process of biological evolution, it must be reasonable for organisms to have some instinct, otherwise it is not necessary to evolve this instinct, and the choice of biological evolution is often the most scientific choice. The author thinks that swallows and insects choose to lower their flying height on cloudy days in order to prevent lightning damage and raindrops and hail.

Lightning is powerful enough to shoot down a huge plane, and swallows and insects can't compete with lightning, raindrops and hail. Historically, a large number of birds and insects must have been killed by lightning, raindrops and hail in nature. Therefore, after millions of years of evolution, today's swallows and insects have an instinct to feel whether there will be lightning, raindrops and hail. Whenever it rains, as long as there is a little possibility of raindrops, hail and lightning, they will lower their flying height and move to the ground where they can escape in time to avoid being hit by raindrops, hail and lightning at high altitude.

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