The testes are abdominal but descend during the breeding season. The cutting edge of the first upper incisor is straight, and the incisors are separated from the mouth cavity by lip folds that have a fine velvety covering. The skull is arched and slightly constricted between the orbits. The caecum is the largest part of the digestive tract, having a capacity up to 10 times that of the stomach. Habitats include forests, shrub-overgrown areas, grasslands, tundra, and alpine slopes.
Most activity is in the evening or at night.
Those rabbits that are weak runners generally shelter in burrows. Hares sometimes shelter in caves or rock crevices. Hares and rabbits also avoid danger by their keen senses of hearing and smell and by the use of alarm signals, such as drumming with the hind feet. This thumping, which can be heard by humans at a distance of several meters, apparently can be detected by other leporids at a considerably greater distance. Some rabbits emit loud, shrill screams when frightened or captured.