Cats, chickens, ducks, dogs and other animals will change their hair before winter and summer.

If we look closely, we will find that the number and structure of their hair or feathers will change to some extent. In winter, the fluff content in animal fur or bird feathers will increase greatly, which improves the warmth retention of animal fur or bird feathers and is the adaptability of animals to the cold climate in winter.

Summer is the opposite.

The root cause is the role of genes.