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By Anna Bess Sorin and Phil Myers
The family Leporidae consists of 11 genera and around 54 species, commonly known as hares and rabbits. Hares (genus Lepus) are generally larger than rabbits, have longer, black tipped ears and live solitary lives. Hares are born with open eyes, hair, and they can run within a few minutes of birth. Rabbits are born blind, naked, and remain in a fur-lined nest their first days of life.
Most leporids are of medium size, from around 300 gm weight to domestic breeds that weigh 7 kg. They have thick, soft fur, and they range in color from white to dark brown. Northern species may undergo a seasonal molt from a summer brown pelage to a winter white. The ear pinnae of leporids are generally longer than wide. The limbs are long, and the hindlimbs are longer than forelimbs and in most are well adapted for running. Movement of the limbs, especially the distal elements, is mostly limited to one plane. The soles of the hind feet are covered with hair. The toes terminate in long, nearly straight claws. The tail is short and sometimes conspicuously marked. Leporids have 
clavicle, but it is rudimentary and does not limit movement of the scapula. The species of leporids vary considerably in their locomotion. Some are accomplished leapers and bounders, avoiding predation by outdistancing the predator. Some jackrabbits have been clocked at 70 km/hr, an astonishing speed for a small animal. Others are scamperers, relying on hiding rather than speed to avoid being eaten.
The skulls of leporids are unmistakeable. They are arched in profile and only slightly constricted between the orbits, very unlike their condition in related pikas. Supraorbital processes are present and consist of anterior and posterior processes. The rostrum is long and wide, and on its sides the maxillae are distinctively pitted. The squamosals and parietals may also be somewhat pitted. The zygomatic arch is broad; the jugal is short; and the bony part of the external auditory meatus is tubular and vertically directed.
The dental formula is 2/1, 0/0, 3/2, 3/3 = 28 in most leporids. The first incisors are enlarged, and the second are small, peglike, and located immediately posterior to the first. The first incisors resemble those of rodents, except that they are completely encased by enamel. Canines are absent, and a large diastema separates incisors from cheekteeth. The cheekteeth appear relatively simple, with the occlusal surface being made up of two transverse ridges. The cheekteeth are strongly hypsodont in most species.
Female leporids are larger than males, an unusual condition among mammals. Those species that are strong runners tend to rest in exposed nests or under small shelters. The poorer runners generally shelter in burrows. Hearing is especially important, and many leporids use their hind limbs to drum out alarm calls that can be heard at a long distance.
Habitats of leporids include forests, grasslands, and tundra. They feed on plant material, and they are not known to store food as many pikas do. Leporids are often prized for their fur, meat, for recreational hunting and as pets. Occasionally when in high numbers they can damage crops and compete for forage with livestock.
The fossil record of leporids extends to the Middle Eocene. Closely related groups, however, can be found all the way back to the Paleocene.
Literature and references cited
Paradiso, J. L. 1975. Walker's Mammals of the World, Third Edition. Johns Hopkins University Press, Baltimore.
Savage, R. J. G. and M. R. Long. 1986. Mammal Evolution, an Illustrated Guide. Facts of File Publications, New York. 259 pp.
Diersing, V. E. 1984. Lagomorphs. Pp. 241-254 in Anderson, S. and J. K. Jones, Jr. (eds). Orders and Families of Recent Mammals of the World. John Wiley and Sons, N.Y. xii+686 pp.
Vaughan, T. A. 1986. Mammalogy. Third Edition. Saunders College Publishing, Fort Worth. vii+576 pp.
Wilson, D. E., and D. M. Reeder. 1993. Mammal Species of the World, A Taxonomic and Geographic Reference. 2nd edition. Smithsonian Institution Press, Washington. xviii+1206 pp.
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Contributors
Anna Bess Sorin (author), University of Michigan. Phil Myers (author), Museum of Zoology, University of Michigan.
