Because it's safer there! Rabbits are nature's fast food. Just about everything that eats other animals will eat a rabbit, and that includes birds of prey and large predators like wolves, either of which have a tough time getting underground. read more
Short form: rabbits, which are ground-oriented animals - not all species, but many, including the European wild rabbit, from which our domestic (pet and livestock) rabbits are descended - dig and live in burrows and warrens for three main purposes; protection against predators, shelter from weather, and to provide a safe and comfortable place for kits to be born and raised. read more