The reasons why rabbits make cooing sounds:

1. Hungry. When a rabbit feels hungry, its stomach will make a growling sound. When the owner hears it, he should feed the rabbit as soon as possible.

2. Indigestion. If the rabbit eats too much or eats some indigestible food, the rabbit's abdomen will have gurgling bowel sounds.

3. Unhappy. If a rabbit makes a cooing sound, it means that the rabbit is very angry, usually accompanied by stomping behavior. The owner should not approach it at this time, otherwise it will be attacked.

4. Fear. When a rabbit is in a new environment or frightened by some noise, it will become nervous and frightened, and will make a cooing sound.

5. Estrus. Rabbits in estrus will make cooing sounds in order to attract the opposite sex.