2. The cat's tail vibrates vertically.

3. What does the cat's tail shake mean?

The cat's tail stands up and vibrates and meows.

1. The vertical vibration of cat's tail is mainly caused by stretching, vigilance and estrus.

2. First, cats stretch from time to time, usually when relaxing.

3. Second, when a cat is threatened, it will generally bow its back and erect its tail.

Thirdly, cats in estrus are very eager to mate, so female cats will show their reproductive mouths by raising their tails to facilitate mating.