What small animals will react before the weather changes?

Before the weather changes, fish, chickens and snakes will have some obvious reactions.

For fish, they depend on oxygen in water to survive. When the weather is clear, the air pressure is high, and there is enough oxygen in the water, the fish will sink to the bottom. When it rains, the air pressure is low and there is no oxygen in the water, so the fish will float to the surface.

For chickens, because they have no sweat glands, they often spread their wings to dissipate heat in hot summer. In rainy weather, when the weather becomes more sultry, chickens don't want to go into the nest because the temperature of the nest is higher at this time.

For snakes that are very sensitive to humidity, when the humidity in the air increases before rain, snakes will climb from low places to higher places.