Leporidae

Diversity

The family Leporidae, consisting primarily of rabbits and hares, includes 54 species from 11 different genera. Leporids range in mass from 300 grams (1.4 lbs) in pygmy rabbits to 5 kilograms (11 lbs) in arctic hares . Adult head and body length ranges from 250 to 700 mm. Unlike most mammals, females are usually larger than males. Color patterns vary between species and across seasons, and range from black to reddish brown to white. Leporids are widely distributed and have adapted to a broad range of habitat types. They can be found throughout the world with very few exceptions. Habitat type affects pelage color as well as litter size. Some leporids are extremely social, living in large communal dens, while others are solitary, coming together in groups or pairs for mating purposes only. The term 'true hares' includes hares and jackrabbits and consists of those species in the genus Lepus ; all remaining species are referred to as rabbits. While hares are well adapted for running long distances, rabbits run in short bursts and have modified limbs adapted for digging. Hares have long muscle fibers in contrast to the short fibers found in rabbit muscle. Hares are often larger than rabbits, have black tipped ears, and have distinctly different skull morphologies.

Geographic Range

Similar to its parent order, Lagomorpha , the family Leporidae has a wide geographic range. Leporids occupy most of the world’s land masses with the exception of southern South America, the West Indies, Madagascar, and most islands southeast of Asia. Although originally absent from South America, Australia, New Zealand, Java, leporids have been introduced to these locations during the last few centuries. The broad geographic range of leporids is largely due to introduction by humans.

• Biogeographic Regions
• nearctic nearctic
  • native native
• palearctic palearctic
  • native native
• oriental oriental
  • native native
• ethiopian ethiopian
  • native native
• neotropical neotropical
  • introduced introduced
• australian australian
  • introduced introduced
• oceanic islands oceanic islands
  • introduced introduced
  • native native

• Other Geographic Terms
• holarctic holarctic
• cosmopolitan cosmopolitan
• island endemic island endemic

Habitat

Leporids can be found in a wide range of environments, from open deserts to boreal forests. Habitat preference and cursorial ability are tightly linked, and as a result, hares and rabbits have distinct habitat requirements. Hares are most often found in open habitat where they can use their speed to evade potential predators. They also rely on their well-camouflaged pelage to hide from predators among the shrubs and rocks. However, some hare species, such as snowshoe hares and Manchurian hares , are well-adapted forest dwellers. While hares are most often found in open habitats, rabbits are confined to habitats with dense cover where they can hide amongst the vegetation or in burrows. Some species of rabbit, such as swamp rabbits and marsh rabbits are excellent swimmers and are considered semi-aquatic. In short, cursorially adept leporids reside in open habitats, whereas cursorially challenged species reside in closed habitats.

• Habitat Regions
• temperate temperate
• tropical tropical
• polar polar
• terrestrial terrestrial

• Terrestrial Biomes
• tundra tundra
• taiga taiga
• desert or dune desert or dune
• savanna or grassland savanna or grassland
• chaparral chaparral
• forest forest
• rainforest rainforest
• scrub forest scrub forest
• mountains mountains

• Wetlands
• marsh marsh
• swamp swamp
• bog bog

• Other Habitat Features
• suburban suburban
• agricultural agricultural
• riparian riparian

Systematic and Taxonomic History

Recent molecular evidence suggests that most leporids arose from a single rapid diversification event during the mid- to late Miocene , between 12 and 16 million years ago, in central Asia. The earliest leporid fossils in the New World are known from the late Eocene , whereas the oldest fossils from Asia are from the mid-Oligocene . As is the case with many other mammalian families, the phylogenetic history of Leporidae is hotly debated, as many morphologists, paleontologists, and molecular biologists believe that Lagomorpha , the parent order of Leporidae, should fall within Rodentia . A single, well-supported classification of lagormophs and leporids has yet to be established. Adding to this confusion, the genus Lepus , which includes all hares, is in a state of disarray regarding its phylogeny and which species should fall within the genus.

Previously, all lagomorphs were classified as a family within the order Rodentia , under the name Duplicendentata. Based on fundamentally distinct differences in tooth morphology, however, Duplicendentata was reclassified as its own order, Lagomorpha . This change in classification was met with strict opposition, which resulted in the term "Glires", representing the combined clades of rodents and lagomorphs. Lagomorphs are also linked to a variety of other mammalian taxa, such as Artiodactyla . In 1996, protein sequencing of rabbits, primates , and rodents suggested that lagomorphs are more closely related to primates than to rodents .

Several synapomorphies help define members of Leporidae . For example, the cheek teeth of leporids are high crowned (i.e., hypsodont) and bilophodont and some of the premolars are molariform. These adaptations are most likely the result of their herbivorous lifestyle. They also have a second set of incisors (present in all lagomorphs ), which are immediately posterior to their primary incisors. Leporids exhibit a number of synapomorphies in skull morphology as well. The maxillae, parietal, and occipitals are all highly fenestrated, they have prominent post- and supraorbital processes, and the external auditory meatuses are tubular.

Physical Description

Leporids exhibit a great deal of physical diversity. European hares , one of the largest extant members of the family, reach a maximum size of 75 cm and 5 kg and pygmy rabbits , one of the smallest, reach a maximum size of 29.5 cm and 0.46 kg. Domestic leporids can be significantly larger, with an average weight of 7 kg. Female leporids are larger than males, an unusual condition among mammals. Leporids have long hind limbs and feet. Their ears, which are also relatively long, are proximally tubular with the lowest point of the external auditory meatus situated well above the skull. Pelage colors range from brown to black to white. Although spots are relatively common in domestic leporids, most wild species have relatively subdued coloration that helps them blend in with their surroundings. The Sumatran rabbit is one of two species with stripes. Neither albanism nor melanism are uncommon in leporids, and some species that inhabit higher latitudes have white coats during the winter, which are then molted during spring. Most leporids are counter colored, with dark-colored dorsal pelage and light-colored ventral pelage. Pelage texture can be thick and soft or coarse and woolly (e.g., hispid hares ) and may become increasingly sparse along the length of the ears. Rabbits and hares have short bushy tales, which are sometimes conspicuously marked, and the soles of their hind feet are covered with hair. The toes terminate in long, slightly curved claws.

Leporid skulls are unmistakeable. They have an arched profile and are only slightly constricted between the orbits, unlike those of their close relatives the pikas . They have prominant post- and supraorbital processes and the parietal, occipital and maxillae are fenestrated . In some species, the squamosals are fenestrated as well. They have a moderately robust zygomatic arch, a relatively short jugal, and tubular external auditory meatuses that are vertically positioned. The dental formula of most leporids is 2/1, 0/0, 3/2, 3/3 = 28. The primary incisors are enlarged, and the secondary are small, peglike, and located immediately posterior to the primaries. The primary incisors resemble those of rodents, except that they are completely encased in enamel. Canines are absent, and a large diastema separates the incisors from the cheek teeth. Their cheekteeth (i.e., molars and premolars ) have relatively simple cusp morphology, with the occlusal surface being made up of two transverse ridges (e.g., bilophodont ). The cheekteeth are strongly hypsodont in most species.

Rabbits and hares are often differentiated from pikas by the length of their tails and ears. Tail length in leporids ranges from 1.5 cm to 12 cm. Rabbits and hares are characterized by their elongated hind limbs and feet and their ears, which can reach 17 cm in antelope jackrabbit . Pikas have short, rounded ears whereas the ears of leporids are significantly longer than they are wide.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• female larger

Reproduction

Most leporid species are polygynandrous. During mating season males and females form small groups in which males compete for access to estrus females and establish a social hierarchy. European Rabbits serve as an exception as they are highly social and have established hierarchies prior to mating season. Males find and attract mates by flagging their tail, involuntary urination, and rubbing against the female prior to copulation. Both sexes have multiple mates and females mate soon after giving birth or while carrying a litter. Gestation typically lasts longer in hares than in rabbits. For example, gestation lasts approximately 55 days in mountain hares and 30 days in European rabbits . Hares are born in a precocial state, fully furred with their eyes open, and are able to run a few hours after parturition. Rabbits are born in an altricial state and are able to see a few days after parturition.

• Mating System
• polygynandrous (promiscuous) polygynandrous (promiscuous)

Some members of the family Leporidae do not have a specific breeding season while others breed during spring and summer. Female ovulation is induced during copulation, about twelve hours after insemination, and females can come into estrus at various times throughout the year. Many species mate immediately after or just before parturition, as females are able to carry two different litters at once (i.e., superfetation). Leporids have high reproductive potential and can produce several litters per breeding season, with several young per litter. Litters usually consist of 2 to 8 young with a maximum of 15 young rabbits (kittens) or hares (leverets) per litter. Resource abundance and quality play a major role in fecundity. For example, Alaskan hares and arctic hares are subjected to prolonged periods of resource scarcity during the winter and have only one litter per year. Black-tailed jackrabbits and antelope jackrabbits live in desert environments and produce several litters a year; however, the litters of these two species are relatively small, containing only 1 to 3 young.

Hares are born fully furred, with open eyes and are able to run a few hours after birth. Rabbits are born with no hair and closed eyes but often have full pelage and open eyes within a couple of days after birth. Sexual maturity and weaning can occur at a young age for both groups but varies according to species. Generally, sexual maturation can occur from 3 to 9 months after birth in rabbits and 1 to 2 years after birth for hares. Females are larger than males in most species, which is unusual in mammals, and are able to reproduce before males. Weaning age is also species specific, but females generally nurse young for at least 3 to 4 weeks, beginning the weaning process about 10 days after parturition.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• year-round breeding year-round breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• induced ovulation induced ovulation
• fertilization fertilization
• viviparous viviparous
• post-partum estrous

Leporids employ a reproductive strategy known as "absentee parentism". In hares, precocial leverets are born in forms, small depression in the ground or surrounding vegetation, while altricial rabbit kittens are born in well-formed, fur-lined nests, constructed in underground chambers or in dense vegetation. Maternal care in leporids is limited to one visit every twenty four hours, usually lasting no more than 5 minutes. Mothers nurse their young during this brief period, which usually occurs during the evening. In species that create subterranean nests for their young, the entrances to these chambers are re-covered after each visit. In form nesting hares, each leveret disperses about 3 days after birth to find their own hiding spot, but rejoin their litter-mates everyday around sunset for their daily nursing bout. Absentee parentism is thought to have evolved as a predator defense mechanism. Leporid milk is extremely rich in fat and protein and is rapidly pumped into offspring during nursing bouts. Paternal care is limited to protecting offspring from rival females.

Prior to the birth of the kittens, rabbit mothers prepare a fir-lined nest for her young. Some species create an underground nest that is either part of a communal den or a remote “brooding tube” dug by the mother for the specific purpose of raising her young. Other species give birth in forms, which consist of small surface depressions filled with chewed-up twigs and leaves, or small depressions among the shrubs. Hares give birth above ground in a nest heap or on a patch of exposed soil.

Hares are precocially born while rabbits are altricially born. Sexual maturity and weaning can occur at a young age for both groups but varies according to species. Weaning generally begins about 10 days after birth and can last anywhere from 17 to 23 days depending on the species. Sexual maturation can occur from 3 to 9 months after birth in rabbits and 1 to 2 years after birth for hares. In social leporids, a mother's position in the hierarchy can affect the social status of their young.

• Parental Investment
• altricial altricial
• precocial precocial
• male parental care male parental care
• female parental care female parental care
• pre-hatching/birth
  • provisioning
    • female
• pre-weaning/fledging
  • provisioning
    • female
• pre-independence
  • provisioning
    • female
  • protecting
    • male
• maternal position in the dominance hierarchy affects status of young

Lifespan/Longevity

Leporid’s face a number of factors that affect longevity, the most notable being heavy predation from a variety of mammalian, reptilian, and avian predators. In their natural environment, populations of certain species have been shown to have an average lifespan of less than a year. The oldest recorded age for European hares in the wild was 12.5 years with the maximum age estimated to be between 12 to 13 years.

Behavior

Some leporids are known to dig burrows or occupy those abandoned by other species. Only 4 species of rabbit ( European rabbits , pygmy rabbits , Amami rabbits , and Bunyoro rabbits ) are known to dig their own burrows, while some hares are known to dig burrows to escape extreme temperatures. For example, black-tailed jackrabbits and cape hares are desert species and dig burrows to escape high temperatues, whereas artic hares dig burrows in the snow to escape the bitter cold. Many species create forms, depressions in the ground or surrounding vegetation, for rest and protection.

Predation is a constant threat in the lives of leporids and has likely served as significant selective force in their evolution. For example, the musculoskeletal morphology of hares allows for prolonged periods of high speed running, which helps them escape predators. Rabbits, which have shorter legs and more compact musculature than hares, are less efficient runners and elude predators by running into holes and burrows. These markedly different predator avoidance strategies define the rabbit’s and hare’s differing migratory patterns. Hares typically travel long distances and have larger home ranges than rabbits, which are usually restricted to the vicinity of their subterranean safe havens and have relatively smaller home ranges and territories.

Leporids are generally solitary and typically only congregate during mating season or as a predator defense mechanism during spring feeding bouts. For example, while arctic hares are solitary for a large portion of the year, they also form large groups during the spring as a means of reducing per-capita risk of predation. European rabbits have a uniquely complex social system involving large subterranean communities and a highly developed burrow system.

• Key Behaviors
• terricolous
• fossorial fossorial
• saltatorial saltatorial
• nocturnal nocturnal
• crepuscular crepuscular
• motile motile
• migratory migratory
• sedentary sedentary
• solitary solitary
• territorial territorial
• social social
• dominance hierarchies dominance hierarchies

Communication and Perception

Very few species of leporids communicate through auditory methods, as most rely on their senses of sight and smell for intraspecific communication. However, certain species (e.g., volcano rabbits ) rely heavily on vocalizations for intraspecific communication. Though leporids are typically silent, they still posses a highly developed and acute sense of hearing and emit high pitched distress calls when captured by a predator. For example, European rabbits , brush rabbits , and Audubon's cottontails are known to thump the ground with their hind feet to warn conspecifics of potential danger (e.g., approaching predators). Many leporids have white fur on the ventral surface of their tail, which they silently wave at conspecifics to warn of a predator's presence.

Leporids possess large, protruding eyes that are laterally positioned near the apex of the skull. The position and protrusion of the eyes help them detect predators over a wide visual arc and aid in overcoming the low light availability during crepuscular and nocturnal conditions, during which they are most active.

All Leporids have scent glands in the groin, cheeks, and under the chin that are used to rub pheromones on their coat during grooming. These glands and the pheromones they produce likely play an important role during mating. Glandular activity in male leporids, specifically the amount of pheromone produced and its degree of pungency, is correlated with testicle size. It has been suggested that pheromones serve as a status marker that identify one's position in the social hierarchy.

• Communication Channels
• visual visual
• acoustic acoustic
• chemical chemical

• Other Communication Modes
• pheromones pheromones
• scent marks scent marks
• vibrations vibrations

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• vibrations vibrations
• chemical chemical

Food Habits

Leporids are obligate herbivores, with diets consisting of grasses, clover, and limited amounts of cruciferous (e.g., plants from the Brassicaceae family such as broccoli and brussels sprouts) and composite plants. They are opportunistic feeders and also eat fruits, seeds, roots, buds, and the bark of trees. During periods of high resource abundance, leporids tend to select forage in pre-reproductive and early reproductive stages of development. In general, the leporid diet is deficient in essential vitamins and micro-nutrients. Plant forage is high in fiber and contains cellulose and lignin as well. Mammals do not possess the digestive enzymes needed to breakdown these compounds. To compensate for this, however, the leporid caecum is up to ten times longer than their stomach and contains a diverse microbial community that helps break down cellulose and lignin. In addition, gut flora passing from the cecum into the small intestine are a significant source of protein for leporids, which have a notoriously protein deficient diet. Leporids are also coprophagic, re-ingesting soft green fecal pellets produced by the cecum. In addition to offsetting their dietary deficiencies, is has been suggested that coprophagy in leporids developed as a predator defense mechanism, allowing them to subsist in the safety of their burrows.

• Primary Diet
• herbivore herbivore
  • folivore folivore
  • frugivore frugivore
  • granivore granivore
  • lignivore

Predation

Leporids are a major prey item for a large number of mammalian and avian predators including humans , owls , hawks and eagles , falcons , wild, domestic, and feral canids , wild, domestic and feral felids , a number of different mustelid species, and some species of ground squirrel . Predation has likely had a major impact on the evolution of leporids as they are clearly adapted for fast and efficient cursorial locomotion . Their hindlimbs are significantly longer than their forelimbs, which gives them the ability to run in a zig-zag fashion increasing their chances of evading predators. While hares prefer to outrun their pursuers, rabbits find safety in dense cover or in a nearby burrow. Their large ears help them detect approaching predators, and the lateral position of their eyes gives them a complete 360 degree field of vision. Some species, such as snowshoe hare , have large pads on their feet that act as gripping cushions as they run across deep snow to evade predators. Some leporids are especially well adept at hiding from predators. For example, European hares practice motionless “ducking”. Upon detecting an approaching predator, they decrease their heart rate by half, which allows them to remain exceptionally still. Ducking also reduces respiration rates and probably decreases sounds produced during respiration.

Many cold-adapted leporids molt before winter and summer, which helps camouflage them from predators regardless of season. Winter pelage , which is typically snowy-white , consists of longer and denser hair that increases the coat's insulative capabilities. The winter coat is then molted in the spring, as the the typical brown summer pelage returns. Young hares are born above ground and are able to see and evade predators a few hours after birth. Rabbits are often born in a fur-lined underground nest. After nursing, mothers exit this nest from a secure “brooding tube”, which they carefully conceal after each visit. Rabbits are born with their eyes closed, and must be nursed before they are able to evade predators.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

Long thought of as pests, rabbits and hares are well known for the damage they inflict on agriculture. As generalist herbivores, leporids are known for their voracious appetite and high reproductive potential. Their role as pests often overshadows their important role in maintaining canivore biological diversity, as leporids are an integral piece of the carnivore food chain. Their importance as a food source for small to medium-sized carnivores is well-illustrated by the 10 year cycle in which Canada lynx abundance closely mimics that of Snowshoe hare .

Leporids are host to a diverse array of endo- and ectoparasites. Many species of parasitic flatworms ( Cestoda and Trematoda ) and roundworms spend at least part of their lifecycle in the tissues of leporid hosts. Leporids are also vulnerable to various forms of of parasitic arthropods including ticks , mites , fleas , mosquitoes , and flies . Leporids also host various forms of parasitic protozoa (e.g., coccidians ). Myxomytosis and rabbit haemorrhagic disease, caused by members of the viral genus Lagovirus , have resulted in the death of millions of wild and domestic leporids.

• Ecosystem Impact
• keystone species keystone species

Economic Importance for Humans: Positive

Beginning in the middle ages when Benedictine monks first domesticated them, leporids have had a long and beneficial impact on humans. For centuries rabbits have been an affordable source of protein to the general public, and their dense and soft pelts have provided materials for warm and insulative clothing. Today they are used as model organisms in biomedical research and are popular as game animals and as pets.

• Positive Impacts
• pet trade pet trade
• food food
• body parts are source of valuable material
• research and education

Economic Importance for Humans: Negative

Leporids have had a long history of wreaking havoc on ecological systems and agriculture. Their high reproductive potential coupled with humankind’s desire raise them as a domestic animals has resulted in their nearly global distribution. In Australia, European rabbits have been credited with driving many marsupial species to extinction and on the Hawaiian Island of Laysan, rabbits have foraged 22 of 26 native plant species into extinction. Occasionally, leporids can damage crops and compete for forage with livestock.

Leporids can be vectors for many diseases that are transmittable to humans and domesticated animals. The most notable of these pathogens include tularemia or "rabbit fever", myxomatosis, coccidiosis, and pasteurellosis. Most diseases are contracted via the preparation and consumption of tainted meat. However, many diseases, like coccidiosis, are relatively species specific and only pose a threat to humans with significantly weakened immune systems.

• Negative Impacts
• injures humans
  • causes disease in humans causes disease in humans
  • carries human disease
• crop pest
• causes or carries domestic animal disease causes or carries domestic animal disease

Conservation Status

Thirteen species within Leporidae are considered threatened or near-threatened by the International Union for the Conservation of Nature (IUCN), 7 of which are either endangered or critically endangered. Of the 62 species listed by the IUCN, those threatened with extinction are often the most primitive. As leporid habitat is being destroyed to create room for crops, irrigation, and ranch lands, many species of rabbits and hares are forced to persist on remnant habitat islands that result in significantly decreased genetic diversity and ultimately, genetic inbreeding. Many native species are also vulnerable to increased competition for resources with invasive rabbits, the introduction of new pathogens, and the introduction of new predators. While habitat destruction poses the biggest threat to many native leporids, they are also vulnerable to competition with livestock for food resources, over hunting, and poisoning by farmers. Suggested conservation measures include the eradication of exotic predators, reducing habitat destruction and fragmentation, creating strict hunting regulations and enforcing those already in place, the establishment of habitat reserves, and increasing public awareness about the importance of leporid conservation efforts.

Additional Links

Encyclopedia of Life

Contributors

maya silberstein (author), University of Michigan-Ann Arbor, Phil Myers (editor), University of Michigan-Ann Arbor, John Berini (editor), Animal Diversity Web Staff.

References

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