Why do swans always sleep standing on one foot?

Swans stand on one foot when they sleep, one for the purpose of combining work and rest, and the other for vigilance and defense.

First, relieve muscle fatigue.

When swans rest, they don't always use the same foot. Instead, they stand on their right foot for a while, then put on their left foot and stand on their feet alternately to avoid fatigue. So that your feet can relax in turn.

Second, be alert to defense.

Standing on one foot, you can see farther and guard against the sudden attack of the enemy. If the enemy comes while sleeping, you can run away and fly away at once. The take-off time of standing on one foot is faster than that of standing on both feet.

In nature, not only swans like to stand upright on one leg, but also many birds stand on one leg when resting, such as cranes, storks and ducks.

? Extended data:

Swan is the largest migratory bird.

Swan is a large bird, with a maximum length of 1.5 meters and a weight of more than 6000 grams. Swan, also known as white swan and mandarin fish, is a large-scale swimming bird, with a body length of about 1.5m and a weight of over 10kg. The whole body has white feathers, the mouth is mostly black, and the upper mouth is yellow to the nostrils.

Their heads and necks are very long, accounting for about half of their body length. When swimming, their necks are often straight and their wings are connected. Swan has become the embodiment of innocence and kindness since ancient times because of its elegant posture.

Swan distribution: It breeds in the north and west of China and overwinters in the central and southeast coast of China. Every year in mid-September, when they move south, they often form a small group of 6-20, forming a "one" or "people" line, singing while flying.

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