Rabbits thump their back legs when they feel that there is danger nearby in order to warn others in the warren. The rabbits detect this danger through any of their senses including when they smell something in the air like smoke, when they see a threat like a fox or when they hear suspicious moving noises nearby.
Rabbits don’t have vocal abilities that are effective, so using their legs to thump the ground is a major way for them to communicate with others that are in their group. For those who have rabbits as pets, the rabbits do this to warn humans of danger as well. When thumping, a rabbit stands high on all four of its feet, with their ears perked up. They then lift their hind feet and thump the ground with them to make noise and vibrations that can be heard by all the rabbits and other animals nearby. Rabbits stay alert while in this state, sometimes taking a few seconds between thumps, but sometimes taking minutes or even as long as an hour. The rabbit thumps every time they sense more danger, and they don’t stop thumping until they are convinced that the danger has passed and they are safe once again.