Leporids belong to the family Leporidae, a group that includes rabbits and hares. Along with pikas (family Ochotonidae), they constitute the order Lagomorpha and are, therefore, called lagomorphs. However, unlike pikas, these mammals are characterized by long, powerful hindlimbs, large ears, protruding eyes, and short, furry tails. They also have slightly curved claws and bushy soles that provide a strong grip on the ground, making them well-adapted to a cursorial (running and hopping) lifestyle.
These small to moderate-sized mammals are native to all continents except Antarctica and Australia, although some species, such as the European rabbit, have been introduced to Oceania. As obligate herbivores, leporids primarily feed on grasses, herbs, clover, and other plants. However, they opportunistically consume roots, seeds, fruits, tree bark, and occasionally carrion.
All leporids share a similar body shape and size range, from the small Tres Marias cottontail, measuring 8 in (21 cm), to the large desert hare, which can grow up to 30 in (76 cm) in length. Among the largest species is the European hare, measuring approximately 29.5 in (75 cm) and weighing around 11 lb (5 kg). In contrast, the pygmy rabbit, one of the smallest species, measures 11.6 in (29.5 cm) and weighs about 1 lb (0.46 kg). Females are typically larger than males, exhibiting sexual dimorphism.
These medium-sized mammals have long hindlimbs with four toes and short forelimbs equipped with five toes. Their toes are covered with hairy soles and end in slightly curved claws, enhancing grip and supporting their cursorial lifestyle. They have short, bushy tails that are often conspicuously marked.
Leporids possess long, mobile ears with excellent hearing and large, protruding eyes adapted for nocturnal vision.
Their bodies are covered in soft, thick fur that may range from coarse to woolly, with colors varying from brown to black to white. Most leporids exhibit countershading, with darker dorsal fur and lighter ventral fur. Some species, such as the Sumatran and Annamite striped rabbits, have striped pelage.
Leporids in higher latitudes develop snowy white coats during winter, which molt into darker shades in summer. Wild species generally have more subdued pelage compared to their domesticated counterparts, which helps them camouflage with their surroundings.
Leporid skulls feature an arched profile with minimal constriction between the orbits, unlike their relatives, the pikas. The skulls have prominent postorbital and supraorbital processes, as well as fenestrations in the parietal, occipital, and maxilla bones. They also have a moderately robust zygomatic arch and a relatively short jugal bone. The external auditory meatuses are tubular and positioned vertically.
Leporids have large primary incisors, fully covered in enamel, unlike rodents. Their secondary incisors, located behind the primaries, are small and peg-like. They lack canines, and their incisors are separated from the cheek teeth (molars and premolars) by a diastema. The cheek teeth are bilophodont, consisting of two transverse ridges.
The dental formula of most leporid species is 2.0.3.3/1.0.2.3 = 28.
Initially, all lagomorphs were classified under the order Rodentia as a family, Duplicendentata. However, based on fundamental differences in the tooth morphologies of the two groups, lagomorphs were reclassified into a separate order, Lagomorpha.
Such a reclassification, however, was not universally accepted and led to the formation of a clade called Glires, which included both rodents and lagomorphs. Finally, in 1996, protein sequencing of rabbits, primates, and rodents revealed that these mammals are more closely related to primates than rodents.
Currently, over 70 extant species (grouped under 11 genera) belong to Leporidae. The name of the family is derived from Latin and stands for ‘those that resemble Lepus or hare.’
The common name ‘rabbit’ was initially used for all 11 genera except Lepus, which were called ‘hares.’ However, this naming is not consistent with the current taxonomy, as some members of Lepus are called jackrabbits, while species in the genera Pronolagus and Caprolagus are referred to as hares.
Although recent molecular evidence suggests that most leporids originated from a rapid diversification event around the mid-to-late Miocene Epoch (between 12 and 16 million years ago) in Central Asia, the oldest fossils date back to the Eocene Epoch (around 56 to 34 million years ago). It is believed that they were present in both North America and Asia during this period.
With time, leporids evolved the habits of running and leaping (cursoriality) as identified from fossil records, which stand as a testament to such evolution. For instance, members of the genus Palaeolagus had shorter hind legs than modern leporids, indicating they were adapted to running rather than hopping.
Two fossils unearthed from India and China, dating back to about 48 to 53 million years ago, have been found to possess the characteristic leporid ankle, suggesting they are closely related to the common ancestor of Ochotonidae and Leporidae. Thus, these two groups probably diverged much earlier than 53 million years ago.
Leporids are indigenous to all continents except Antarctica and Australia. In addition, humans have introduced some species, like European rabbits (Oryctolagus cuniculus), to most countries of Oceania.
These mammals have adapted to a wide range of habitats, including forests, deserts, mountains, swamplands, and even tundras. While hares are more adapted to living in open habitats, rabbits typically hide amongst the vegetation or in burrows. Some rabbit species, such as swamp and marsh rabbits, are semi-aquatic and thrive near riverbanks and creek edges. In contrast, species like snowshoe and Manchurian hares are well-adapted to living in the woods.
Both rabbits and hares are obligate herbivores, feeding primarily on grasses, herbs, clover, and sometimes on cruciferous plants, like broccoli and Brussels sprouts. They also occasionally (rather opportunistically) consume roots, seeds, fruits, and tree bark. Some hares are also known to feed on carrion.
These animals are generally solitary but congregate for mating or to avoid predators. They are nocturnal or crepuscular, usually foraging at night or in the evening.
They typically graze on plant materials using their rodent-like incisors. When resources are abundant, they start foraging early during the pre-reproductive and early reproductive stages.
If the food is easily digestible, they process it in the gastrointestinal tract and expel it out of their bodies. However, since plant parts are rich in fiber, cellulose, and lignin, they are difficult to digest. Hence, leporids ferment their food in the cecum using the diverse gut microflora and then excrete the undigested part as soft, green fecal pellets or cecotropes. As coprophagic animals, they reingest these cecotropes (cecotrophy), and their nutrients are absorbed in the small intestine.
Wild rabbits generally live for around 2 years in the wild, but in captivity, they survive around 10 years. Similarly, hares survive a year or so (on average) in the wild, though some species, like European hares (Lepus europaeus), have been recorded to live up to 12.5 years in their natural habitat.
Leporids have a polygynandrous mating system, where both males and females have multiple mates. Typically, males and females form small groups during the breeding season, and the males compete to gain access to females in their estrus. However, some species, like European rabbits, establish this hierarchy way before the mating season.
Males attract mates by flagging their tails, urinating, and rubbing their bodies against females. Interestingly, ovulation in females is induced during copulation, typically occurring 12 hours after insemination.
After a gestation period of about 28 to 50 days, the females give birth to the young. This period is slightly longer in hares than in rabbits since they give birth to relatively well-developed or precocial young with fully furred bodies and open eyes and ears. In contrast, rabbit young are altricial, lack fur, and have closed eyes and ears. While leverets are born in small depressions on the ground (forms), rabbit kittens are born in fur-lined nests within underground chambers. The average litters of both rabbits and hares consist of 2 to 8 young, though they can occasionally carry up to 15 offspring. The mother visits her young only once in 24 hours and nurses them for no more than 5 minutes (absentee parentism).
Depending on the species, the young are weaned anywhere between 17 to 23 days, though the weaning process begins about 10 days after birth. Rabbit young reach sexual maturity between 3 and 9 months, while leverets become sexually mature in 1 to 2 years. Many leporids mate just before or immediately after parturition and are capable of carrying two different litters at the same time.
They are preyed upon by mustelids, canids (such as dogs, wolves, coyotes, foxes, and jackals), ground squirrels, and birds of prey, like owls, hawks, and eagles.
Currently, 62 species of leporids are listed on the IUCN Red List. Among them, seven species are classified as Endangered (EN): the Amami rabbit, European rabbit, Hispid hare, Tres Marias cottontail, Annamite striped rabbit, Common tapeti, and Hainan hare. The Riverine rabbit is listed as Critically Endangered (CR), while the Coastal tapeti is classified as Vulnerable (VU), and the Yarkand hare is Near-Threatened (NT).
The primary threat to leporids is habitat loss caused by the expansion of agricultural land for irrigation. This compels them to live in isolated habitats, causing genetic inbreeding and the subsequent loss of diversity. Additional threats include overhunting, competition with livestock for resources, and poisoning by farmers.
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