CONTENTS

Living Organisms / Animalia / Craniata / Mammalia / Lagomorpha / Leporidae / Lepus / Species

Lepus californicus - Black-tailed jackrabbit (Click photographs/illustrations for full picture & further details)

INDEX - INFORMATION AVAILABLE

Alternative Names (Synonyms)

Names for new-borns / juveniles

• Leveret. (B285.w5b)

Names for males

• Buck. (B285.w5d)

Names for females

• Doe. (B605.1.w1)

General Appearance

General Information

• All hares have well-furred feet. (B147)
• "The upper parts of the body are usually brown or grayish brown, and the underparts are paler or white." (B147)
• Jackrabbits are big, slender-bodied species with long ears. (B147)

Specific Lepus californicus Information

• This species is large and lean, and has long ears and legs. (B430.w2)
• A medium-sized brownish or grizzled Lepus species, with a black dorsal tail stripe. (J469.530.w1)

Newborn:

Specific Lepus californicus Information  

• Furred at birth, basically brown with tail and ear tips black, pale grey round the nose and mouth, and a white spot on the forehead. (J469.530.w1)

Similar Species

• Distinguished from Lepus townsendii - White-tailed jackrabbit by the tail colour: in Lepus californicus the upper part of the tail is black, and this colour extends into a line on the rump/lower back. In contrast, the upper side of the tail is white in Lepus townsendii - White-tailed jackrabbit. (B430.w2, B605.4.w4, J469.288.w1, J469.530.w1)

• Distinguished from Lepus alleni - Antelope jackrabbit by the black patch terminally on the ears and by the lack of much white on the sides. (B605.4.w4, J469.530.w1)

Sexual Dimorphism

References

Species Authors & Referees

• See: DIRECTORY- Organisations working with Rabbits and their Relatives

• Rabbits, Hares and Pikas Status Survey and Conservation Action Plan
• See also: The Electronic Library- further reading for "Rabbits and their Relatives: Health & Management"

Husbandry Information

Notes

• Considered difficult to keep in captivity: death may occur when first handled, and if placed in a cage, may throw itself constantly against the wire until it kills itself. (J469.530.w1)

Management Techniques

• Accommodation Design for Mammals
• Mammal Behavioural Requirements
• Food and Feeding for Mammals
• Mammal Handling & Movement
• Mammal Identification
• Preventative Medicine for Mammals
• Rearing of Mammals
• Reproductive Management of Mammals
• Management of Unwanted or Illegally Held Animals
• Hand-rearing Hares and Jack-rabbits (Lepus spp.)

Measurement & Weight

Notes

LENGTH
Adult: 

Specific Lepus californicus Information

• This species is usually between 465-630 mm in length. (B430.w2)
• Total length 523 - 606 mm. (J469.530.w1)
• Note: body size varies e.g. generally large on most islands around Baja California, but smaller on Carmen Island than on adjacent islands. (J469.530.w1)
• In Kansas, males are smaller (body length and mass) than females. (J469.530.w1)

Newborns: 

Specific Lepus californicus Information

• Size at birth is variable within a litter and depending on the number of individuals in the litter: a singleton is likely to be larger than any individual in a litter of three or four. (J469.530.w1)
• Body length at birth is 29% of adult length. (J469.530.w1)
• In one litter, total length at one day old was 140 mm. (J469.530.w1)

HEIGHT
Adults and sub-adults: --
Juveniles:  --

WEIGHT
Adult: 

Specific Lepus californicus Information

• This species usually weighs between 1,300-3,300 g. (B430.w2)
• Average weight: 2.5 kg.
• Weight range: 1.3 - 3.1 kg. (B605.4.w4)
• Southern Arizona: males 1,980 - 3,375 g, average 2,475 g; non-pregnant females 1,980 - 3,285 g average 2,610 g. (J469.530.w1)
• California: males 2,000 - 2,950 g, females 2,120 - 3,550 g. (J469.530.w1)
• Washington: males 1,510 - 1,880 g; females 1,880 - 2,840 g. (J469.530.w1)

Newborns: 

Specific Lepus californicus Information

• Newborns of this species usually weigh between 96-114 g. (B287)
• 110 g. (B287)
• In one litter, 60 - 71 g, average 66 g. (J469.530.w1)
• Size at birth is variable within a litter and depending on the number of individuals in the litter: a singleton is likely to be larger than any individual in a litter of three or four. (J469.530.w1)

GROWTH RATE 

Specific Lepus californicus Information

• Body length increases from 29% of adult length at birth to more than 90% of adult length by 2.5 months, reaching adult length at 28 weeks. Body mass at one month is only 13% of adult mass, at 2.5 months is 65% of adult mass, and adult mass is reached by 32 weeks. (J469.530.w1)
• Weaning mass:
  • 1.47 kg (12-13 weeks). (B287)
  • 2.3 kg (sd = 0.64; sample size = 9). (B287)

Head and Neck

Notes

GENERAL HEAD STRUCTURE:
Adult:  

Specific Lepus californicus Information 

• This species has long ears. (B430.w2, B605.4.w4, J469.530.w1)
• Ear length ranges from 100 to 130 mm. (B605.4.w4)
• Ear length: 120-147 mm (Average: 131.9 mm). (B430.w2)
• Ear length (dried ear, from notch) 99 - 131 mm; no difference between males and females. (J469.530.w1)
• Note: the size of the ears varies geographically, depending on temperature; the ears are important in heat regulation. (J469.530.w1)
• Vibrissae long and sensitive. (J469.530.w1)

Newborn:

Specific Lepus californicus Information

• Face is flat below the eyes and the muzzle is short and broad at birth, lengthening and narrowing starting at about 10 days old.
• The ears are less than 50% the length of the head at birth and only 22% of adult length; in one litter, ear length was 25-30 mm (average 27 mm). By 15 days they are as long as the head; by 28 days they are about 100 mm long and by 35 days, 115 long, reaching adult length by 12 - 15 weeks. (J469.530.w1)

DENTITION:
Adult:

General Information

• Rabbits and hares have a total of 28 teeth. (B285.w5a)
  • The dental formula for rabbits and hares is i 2/1, c 0/0, pm 3/2, m 3/3 x 2 = 28. (B147, B285.w5a)
  • This differs slightly in Pentalagus furnessi - Amami rabbit, with the molars sometimes being 2/3. (B147, B623.w3)
• The lower tooth rows are closer together than the upper tooth rows. (B147)
• Lagomorphs differ from rodents by having two pairs of upper incisors rather than just the one pair. The additional set of incisors are called peg teeth and are found directly behind the long pair in the upper jaw. (B147, B285.w5a, B605.1.w1)
• At birth, lagomorphs actually have three pairs of upper incisors, but they quickly lose the outer incisor on each side. (B147)
• The incisors are covered completely by enamel. (B147)
• The upper incisors' roots are found in the skull's premaxillary bones. However, the length of the lower incisors' roots varies. (B147)
  • [Note: lagomorphs have teeth which grow throughout their lives. For this reason the portion of the teeth which is not exposed (not above the gum line) is strictly speaking not a "root"; however, it is sometimes convenient to describe it as a root.]
• The first upper incisors have a straight cutting edge. (B147)
• The peg teeth lack a cutting edge. (B147)

EYES:
Adult:

General Information

• Lagomorph eyes are positioned such that they allow for good broad-field vision. (B285.w5a)
• Hares and rabbits have large eyes which are adapted to both their crepuscular and nocturnal activity patterns. (B285.w5b)
• Leporids have "large eyes to increase visual acuity in dim light." (B430.w2)

Newborn:

Specific Lepus californicus Information

• Eyes open at birth. (J469.530.w1)

Legs, Spine and Tracks

Notes

• All hares have well-furred feet. (B147)
• Almost all Lepus species have large hind feet. (B147)

• This species has very long legs. (B430.w2, B605.4.w4)
• Hindfoot length 11 - 135 mm; no difference between males and females. (J469.530.w1)
• Newborn: In one litter, at one day old, hind foot length was 33 - 36 mm (average 34 mm). (J469.530.w1)

Tail

Notes

• Leporids have a short tail. (B147)

• This species has a relatively long tail. (B605.4.w4, J469.530.w1)
• Tail length range for this species: 50-112 mm. (B430.w2)
• Tail vertebrae 75 - 101 mm. (J469.530.w1)
• Note: the upper part of the tail is black and the underside greyish or buffy. (B430.w2, B605.4.w4)
• Newborn: In one litter, at one day old length of tail vertebrae was 18  -20 mm. (J469.530.w1)

Skin / Coat / Pelage

Notes

Adult: 

Specific Lepus californicus Information

• Dorsally brown to grizzled/dark grey, Underside pale grey. The ears are edged with black and sometimes tipped with black. The tail is marked with a black dorsal stripe that may continue as a line onto the lower back, and its underside is buffy or pale grey. (B430.w2, J469.530.w1)
• Fur length about 8 - 9 mm. (J469.530.w1)

Adult Colour variations:  

General Information

• Some Lepus species moult into a white winter pelage (B147, B605.4.w4), the timing of which depends upon the number of daylight hours. (B147)
• "All species that turn white in winter undergo two molts per year. Some species that molt twice, however, do not have a white winter pelage." In these species, the winter pelage is grey, whereas the summer fur is brown. (B147)

Specific Lepus californicus Information

• This species only moults once a year, and it does not acquire a white coat in the winter. (B430.w2)
• The annual moult starts late August to early October, depending on latitude, with short summer hair being replaced by longer hair for the winter
• There is considerable variation in colouration between the subspecies. (J469.530.w1)
  • The pelage of this species varies from greyish-brown to sandy coloured. Such colouration camouflages it against the desert and dry grassland habitats in which it lives. (B605.4.w4)

Newborn / Juvenile: 

Specific Lepus californicus Information

• General colour of fur at birth is brown, with ear tips and tail black, an area of pale grey around the nose and mouth and often a white patch in the centre of the forehead, most visible at 2 - 3 weeks and starting to disappear at 10 weeks, reducing to a poorly-defined white line by 18 weeks. (J469.530.w1)
• A paler immature pelage gradually replaces the darker natal brown pelage, and adult pelage develops at 6 - 9 months, during the first winter. (J469.530.w1)

Detailed Anatomy Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

Notes

Skull

General Information

• Leporids have an arched skull with a slight constriction between the orbits. (B147)
• Lepus species have a skull that is lighter than the skull of rabbit species. (B605.4.w4)

Female reproductive tract

Specific Lepus californicus information:

• Three pairs of mammary glands, one pectoral and the others abdominal. (J469.530.w1)

Male reproductive tract

General Information

• Testes are in the scrotum located in front of the penis (B147)

Specific Lepus californicus information:

• Males lack a baculum. (J469.530.w1) 
• Testes are found in the scrotum during the breeding season, but generally in the abdomen in mid winter. (J469.530.w1)

Digestive system

General Information

• The largest part of the digestive tract is the caecum; this has a capacity up to ten times that of the stomach. (B147)

Specific Lepus californicus information:

• Large intestine length 164 cm. (J469.530.w1)
• Both male and female have rectal glands, either side of the anus, abut 12 mm deep, with a wide external opening, secreting a substance with a strong musky odour. (J469.530.w1)

Natural Diet

Notes

NATURAL DIET:

General Lepus Information

• Hares mainly eat grasses and herbaceous plants, but do also feed on twigs, buds and bark. (B147)

• Isolated cases have been reported of hares capturing and eating voles and young lagomorphs. (B147)

Specific Lepus californicus Information

• This species makes use of a wide variety of food sources, though in ideal situations, the majority of its diet is composed of forbs and grasses, as well as various agricultural crops in certain areas. (B430.w2)

• The Black-tailed jackrabbit is, however, capable of surviving on plants including creosote-bush, which is unpalatable to the majority of mammalian species. (B430.w2)

• In the summer, the majority of the diet is composed of grasses and sedges, and in the winter the diet shifts to shrubs. Shrubs are also consumed during dry seasons in desert regions. (B605.4.w4)

• In sympatry with the Lepus townsendii - White-tailed jackrabbit, the Black-tailed jackrabbit appears to be less selective over the species of plants it consumes. (B430.w2)

• Variable diet, including Artemesia tridentata, Atriplex confertifolia, Atriplex nuttallii, Eurotia lanata, Halogeton glomeratus, Gutierrezia sarothrae, Larrea tridentata, Sporobolus cryptandrus, Opuntia, grasses, crops and fungi. (J469.530.w1)

• Eat gravel and sand; consume about 9.7 g soil per day. (J469.530.w1)

• Thought not to eat flesh, but in Texas reported to feed on horse carcasses. (J469.530.w1)

QUANTITY EATEN:

Specific Lepus californicus Information

• May eat 390 g forage per day. (J469.530.w1)
• Stomach contents weighed average 67 g. (J469.530.w1)

STUDY METHODS:

Specific Lepus californicus Information

• Feeding trials used to assess quantities eaten. (J469.530.w1)
• Mass of stomach contents weighed. (J469.530.w1)

Hibernation / Aestivation

Notes

Haematology / Biochemistry

Notes

HAEMATOLOGY:

• Normal Haematology Values for Lepus californicus - Black-tailed jack rabbit

BIOCHEMISTRY:

• --

Detailed Physiology Notes
(Summary information provided for pertinent species-specific data cross-referenced in WILDPro)

Notes

METABOLISM (TEMPERATURE):

Specific Lepus californicus Information

• The Black-tailed jackrabbit has extraordinary thermoregulation capabilities, which enable it to survive in extremely hot and arid areas. (B430.w2)

• The ears may act as efficient radiators of heat to the cool sky, but when the temperature rises above 40 °C the ear vessels are constricted and the ears held against the back. (J469.530.w1) 

• This species has "a number of physiological mechanisms that reduce water loss, including the ability to increase its resting daytime body temperature, storing heat for nighttime dissipation, and the ablity to reduce its metabolic rate to decrease evaporative water loss." (B430.w2)

• "By increasing blood flow to its long ears and by assuming a slightly splayed standing position, it maximizes the convective transfer of heat." (B430.w2)

• The daily water requirement in summer is about 120 mL/kg; a diet which is at least 68% water is needed to meet this - there is no evidence of black-tailed jackrabbits using water sources. (J469.530.w1)

• Average body temperature 39.2 °C. (J469.530.w1)

• Maximum survivable body temperature 43.7 °C; lethal temperature 45.4 °C, lower critical temperature 12 °C. (J469.530.w1)

• Metabolic rate 0.57 mL oxygen/g/hr at 15 - 35 °C ambient temperature. (J469.530.w1)

RESPIRATORY SYSTEM (RESPIRATION):  

Specific Lepus californicus Information 

• Respiratory rate may increase to as high as 350 breaths per minute at high ambient temperatures. (J469.530.w1)

CIRCULATORY SYSTEM (PULSE/HEART RATE): --

GASTROINTESTINAL SYSTEM (FAECES AND GUT MOTILITY):

General Information

• Lagomorphs have digestive systems which are adapted for processing large quantities of vegetation. (B285.w5a)
• Lagomorphs are well adapted for obtaining the greatest possible value from their food. They produce two types of faecal material: moist pellets and dry pellets. The moist pellets are expelled and then eaten (a behaviour known as caecotrophy (B285.w5a)); this is done with little or no chewing, and as a result the majority of the food passes through the digestive tract twice (this is thought to have the same function as 'chewing the cud' in ruminants). The dry faecal pellets are not eaten. (B147)

• This species is able to obtain most or even all of its water from food. (B430.w2)
• Produce about 545 faecal pellets daily; pellets are about 13 mm diameter, rounded and slightly flattened, and are larger, rather than number increased, when the mass of vegetation eaten increases. (J469.530.w1)
• During the day, while resting, produces soft faecal pellets (caecotrophs) which are eaten directly from the rectum and swallowed whole. These contain 80% water, compared to 74% for the hard faeces, and 46% protein (versus 14% in hard faeces). (J469.530.w1)
• Assimilate about 45% of forage; better assimilation of succulent forage than of dry woody foods. (J469.530.w1)

URINARY SYSTEM (URINE):

Specific Lepus californicus Information

• Excess salt is eliminated through the urine. (B430.w2)

CHROMOSOMES: 

• All the Lepus species have 48 chromosomes. (B605.4.w4)

Specific Lepus californicus Information

• 48 chromosomes. (J469.530.w1)

MUSCULO-SKELETAL SYSTEM:  --

SPECIAL SENSES AND VOCALISATIONS:

General Information

• All lagomorphs use scent products secreted from special glands. (B285.w5a) These glands are located under the chins and in the groin, and are believed to play a key role in sexual communication, as well as in signalling social status in some gregarious species. (B285.w5b)
• Whereas pikas tend to be more vocal, rabbits and hares rely strongly on scent rather than sound as a means of communication. (B285.w5b)
• High-pitched distress squeals are emitted by leporids when captured by a predator. (B285.w5b, B430.w2)
• The North American leporids have large ears with highly-developed hearing, an adaptation which allows them to detect predators when foraging in open habitats. (B430.w2)
• Hares communicate with each other by drumming their feet. (B147)
• Deep grumbling has been reported in Lepus species, and shrill calls are emitted when the animal is in pain. (B285.w5c)
• "When seeking the young for nursing, females call the young and are answered." (B147)

Specific Lepus californicus Information

• Hearing is probably the most important sense for detecting danger. (J469.530.w1)
• Sight is used but appears to be better for detecting movement than detecting still objects at a distance. (J469.530.w1)
• Appear to use smell for detecting food and conspecifics. (J469.530.w1)
• When there is any hint of danger the jackrabbit will raise its ears and often stand on its hind legs, ears erect and nose twitching. (J469.530.w1)
• Usually silent; a piercing cry may be given when this jackrabbit is cornered, handled or injured. Some individuals grunt or growl when handled, similar to the way a female may grunt or growl when being aggressive towards an approaching male. (J469.530.w1)

Feeding Behaviour

Notes

• Lagomorphs are well adapted for obtaining the greatest possible value from their food. They produce two types of faecal material: moist pellets and dry pellets. The moist pellets are expelled and then eaten; this is done with little or no chewing, and as a result the majority of the food passes through the digestive tract twice (this is thought to have the same function as 'chewing the cud' in ruminants). The dry faecal pellets are not eaten. (B147)

Specific Lepus californicus Information

• This species usually feeds among open pastures, rangelands and within commercial crop sites. (B430.w2)
• This species is capable of surviving on limited amounts of food, even when this food is of suboptimum standard, thus enabling the rabbit to survive in extremely hot and arid regions. (B430.w2)
• While foraging, they start hunched up, gradually stretching out to reach food further away, and eventually bringing the hind legs back up under the body to a hunched position once more. It remains alert, often moving its ears around to detect sounds, and raising the head to check its surroundings every 20 -30 s (continuing chewing). When browsing on Prosopis, the jackrabbit rises on its hind legs with the forelegs hanging limply; to reach higher it stands on its toes and places its forefeet on a branch while taking buds, leaves or bark - to as high as 60 cm above ground level. (J469.530.w1)
• Prunes Gutierrezia sarothrae during the period November - March, and in winter also prunes Larrea tridentata at 44 cm obove ground on average, proving a stem 30 - 70 cm long, weighing 11 - 50g. Eats new woody stems, not old wood or leaves, and preferentially takes stems with a higher moisture content. (J469.530.w1)

Parental Behaviour

Notes

General Information

• Male leporids are not generally involved in care of the young. However, if adult females attack young leporids, males will intervene, a behaviour known as 'policing'. (B285.w5b)
• Even maternal care of the young is not particularly prominent in leporids, hence this reproductive strategy is known as 'absentee parentism'. (B285.w5a)
• Leporids demonstrate an unusual system of nursing; the young are suckled only briefly (often less than five minutes) just once every 24 hours. (B285.w5b)
• It is thought that the lack of social contact between the mother and her young is a strategy which diminishes the chances of attracting the attention of predators. (B285.w5b)

Specific Lepus californicus Information

• Females construct a nest for their young, lined with their own fur. (J469.530.w1)
• Females remove the afterbirth from their young after parturition. (J469.530.w1)
• If a female accepts a male for mating on the day of parturition, he may assist in disposing of the afterbirth. (J469.530.w1)
• During the whole nursing period, the female licks the genital and naval areas of her young. (J469.530.w1)
• If a litter has been disturbed and scattered the female actively regroups them. (J469.530.w1)
• When not actually nursing the litter, she stays away from them and does not watch over the young or act to distract predators. (J469.530.w1)
• Females move towards their young at night and away from them during the day. (J469.530.w1) 
• Interactions between mother and young cease by weaning time. (J469.530.w1)

Social Behaviour / Territoriality / Predation / Learning

Notes

General Information

• Most North American leporid species are solitary, but congregations of these animals often occur in favoured feeding grounds. (B430.w2)
• With the exception of the mating season (B147), most Lepus species are solitary. (B147, B285.w5c)
• Hares communicate with each other by drumming their feet. (B147)

Specific Lepus californicus Information

• This species is not considered to be a highly gregarious species. However, in areas of good forage sources, large groups often congregate. (B430.w2, B605.4.w4)
• This is generally a solitary species. (B605.4.w4)
• This species is not generally aggressive, though aggressive behaviour between males, and between females avoiding males is known during the mating season. (B605.4.w4)
• "...where the black-tailed jackrabbit and white-tailed jackrabbit co-exist, the former displaces the white-tailed jackrabbit onto higher, more sparse vegetation and can out-compete it in adaptability to a wider range of habitats." (B605.4.w4)
• Generally not gregarious but groups of as many as 200 - 250 may be seen in winter feeding on e.g. winter wheat. (J469.530.w1)
• During the breeding season, groups of two to five individuals may form. (J469.530.w1)
• Individuals in a given field do not show any social organisation. (J469.530.w1)
• Rarely aggressive to one another and will usually ignore conspecifics which are close by, but sometimes may butt, bite, jump up, run around or avoid a conspecific. (J469.530.w1)
• It is common for two individuals to turn to face each other, with one then trying to head-butt or run in a circle around the other, the second then chasing the first, often trying to bite its flanks, before the activity stops, apparently by mutual consent, and they return to their previous activities. (J469.530.w1)
• If a male seeking a female for breeding encounters another male this may result in a fight or a chase. Fighting between males involves standing up on the hind legs and striking with the forefeet; fur is often loosened. They also bite, particularly the ears, which may become seriously torn. (J469.530.w1)

PREDATION:

• Black-tailed jackrabbits are preyed upon by Canis latrans - Coyote and other large mammalian carnivores, as well as some avian predators including eagles and large hawks and owls. (B430.w2)

PREDATOR AVOIDANCE:

General Information

• Hares will run out into open areas and use their speed in order to avoid predators. (B285.w5b, B605.4.w4)
• Speeds of up to 72 km/h (45 mph) have been reported for hares. (B285.w5b)
• "Instead of seeking cover, hares rely on their well-developed running ability to escape from danger: also on camouflage, by flattening on vegetation." (B285.w5c)
• Jackrabbits can avoid predators by crouching against the ground in any available cover. (B147)
• Jackrabbits can avoid predators by crouching against the ground in any available cover. (B147)
  • Jackrabbits remain well hidden when crouching down in dense cover, but are often highly conspicuous when sitting up being vigilant or when running. (B147)
• Jackrabbits are capable of running for greater distances than true rabbits (Sylvilagus sp.) (B147)

Specific Lepus californicus Information

• Agility and speed are the two main strategies used by this species to avoid predation; it does not usually make use of dense vegetation for cover. When fleeing a predator, the Black-tailed jackrabbit can achieve a horizontal leap of up to 6.1 metres (20 feet), and a vertical leap of nearly 2 metres (6 feet). (B430.w2)
• "In deep vegetation a jackrabbit may attempt to sneak away from an intruder unseen; the usual response is to "freeze" and jump up suddenly when it knows it has been seen." (B605.4.w4)
• Reacts to danger by fleeing, or staying motionless. If vegetation is dense, it may sneak away or run with the body held close to the ground, ears low. After running, it veers to one side; in this way, when it stops it is facing at right-angles to the danger. (J469.530.w1)

POPULATION DENSITIES:

General Information

• Drastic, cyclic population density fluctuations occur in northern Lepus species. (B147)
• Predator population cycles follow Lepus cycles; once predator populations have crashed, and vegetation has had the chance to regenerate, hare population numbers are able to start increasing once more. (B147)

Specific Lepus californicus Information

• The densest populations are found in the semiarid and arid regions in the Western agricultural and range lands. (B430.w2)
• Jackrabbits demonstrate fluctuating population densities, with peaks being reached at intervals of 6 to 10 years. "The number of hares in peak populations also varies substantially."  (B430.w2)
• Densities of 470 hares per km² have often been reported, though densities of up to 1,500 individuals per km² have also been observed. (B430.w2)
• Population densities vary in six to ten year cycles, and in Northern Utah densities of 0.1-1 hare per hectare have been recorded. In Arizona, population densities are similar at 1.2 hares per hectare, though this increases on agricultural land to 1.5-2.7 hares per hectare. Population densities can increase to 34.6 individuals per hectare on isolated wheatfields during the night. (B605.4.w4)

HOME RANGES AND DISTANCES TRAVELLED:

General Lepus Information

• "Habitat type has a marked effect on home-range size within each species, but differences also occur between species." (B285.w5c)
• Lepus species vary greatly in their home range sizes, with some species having home ranges of only 4-20 hectares, and others exceeding 300 hectares. (B285.w5c)
• Areas within a couple of metres of forms may be defended, but home ranges often overlap, often with common feeding grounds. (B285.w5c)

Specific Lepus californicus Information

• Home ranges for this species vary between 10 and 20 hectares (B430.w2). Females generally have slightly larger home ranges than the males. (B430.w2, B605.4.w4)
• In California, the average home range of a Black-tailed jackrabbit is 20 hectares. (B605.4.w4)
• Home range 20 - 140 hectares.
• Home ranges average 16 hectares in Idaho and Kansas. (B605.4.w4)
  • Kansas: adults 5 - 78 hectares, mean 17 hectares; juveniles 4 - 28 hectares, mean 14 hectares. (J469.530.w1)
  • Idaho: rarely moved more than 0.4 hectares; home range was considered to be less than 16 hectares. (J469.530.w1)
• Home range size varies with population density. (B605.4.w4)
• Daily movements occur between shelter and foraging areas. (J469.530.w1)
• Longer dispersal movements do occur, and seasonal movements can occur. (J469.530.w1)

TERRITORIALITY:

General Information

• The majority of hares and rabbits are non-territorial; some hares occupy home ranges of up to 300 ha (740 acres). Ranges of individuals may overlap in favoured feeding grounds. (B285.w5b)

Specific Lepus californicus Information

• Females may charge conspecifics which approach within 5-10 m; this may be a territorial behaviour. (J469.530.w1)

Sexual Behaviour

Notes

• All lagomorphs use scent products secreted from special glands. (B285.w5a) These glands are located under the chin and in the groin, and are believed to play a key role in sexual communication, as well as in signalling social status in some gregarious species. (B285.w5b)
• Male Lepus become bolder during the mating season, and engage in fights with other males, and pursue females. (B147)
• Male Lepus fight by using boxing motions with their forefeet and kicking with their hind feet. (B147)
• Males often bite and kick the females, often leading to serious injury. (B147)

Specific Lepus californicus Information

• Sexual behaviour includes "hunt, approach, chase, boxing match, and copulation." Switching between behaviours can occur rapidly. (J469.530.w1)
• Females may accept males on the day of parturition. (J469.530.w1)
• Promiscuous; a female accepts the first approaching male. (J469.530.w1)
• Intense courtship behaviour occurs involving circling, approaches my both male and female, long chases, and urination during chasing and jumping; these behaviours may take place for 5 -20 minutes before copulation. (J469.530.w1)
• After copulation the male may fall backwards, give a hissing squeal, and leap up again to re-start chasing; up to five copulations may occur. (J469.530.w1)

Activity Patterns, Self-grooming and Navigation

Notes

ACTIVITY PATTERNS: 

General Information

• All the lagomorphs are terrestrial. (B147)

Specific Lepus californicus Information

• In very hot areas, Black-tailed jackrabbits have been known to make use of shallow depressions in the soil. (B430.w2)
• "By day the hares rest under bushes for shelter, but in the Mojave Desert...black-tailed jackrabbits made or enlarged short burrows for protection from the sun." (B605.4.w4)
• After a cold night, they may be found lying on their sides, apparently basking in the sunshine. (J469.530.w1)
• Resting in shelter forms in the daytime, they remain motionless. (J469.530.w1)
• Good at running and leaping. (J469.530.w1)
• Usually runs low to the ground, rather than leaping, but can jump over e.g. small bushes. (J469.530.w1)
• May fail to see a fence and run straight into it. (J469.530.w1)
• These jackrabbits appear to avoid entering water but are seen foraging in e.g. 5 cm deep water, cross rivers at ice jaws, and can swim fast and well, with all but the head and the ears (which are lowered) under water. On leaving the water it shakes to rid itself of water. (J469.530.w1)
• Make trails through vegetation and across fields etc. (J469.530.w1)

SELF-GROOMING:

Specific Lepus californicus Information

• The body is licked, also the pays are licked then used to clean areas such as the top of the head and the ears. (J469.530.w1)
• Dust baths are taken, with the jackrabbit digging a shallow depression in loose sand, rolling in this, then afterwards siting on its hindlegs, licking its forepaws and brushing the sides of the head. (J469.530.w1)
• They shake their heads vigorously "to dislodge mosquitoes from the long ears." (J469.530.w1)
• The ears may be scratched with the hind feet. (J469.530.w1)

CIRCADIAN RHYTHM: 

Specific Lepus californicus Information

• This species is largely nocturnal. (B430.w2, B605.4.w4,  J469.530.w1)
• The Black-tailed jackrabbit rests during the day, often in the shade of a bush or in a shallow scrape. (B430.w2)
• The length of the evening feeding period varies with season, moon phase and weather; longer is spent in feeding in calm, dry conditions than in wet, windy weather. Activity is also reduced by snow or fog. Temperature and rain do not much affect activity. (J469.530.w1)
• Young leverets are motionless during the day and more active at night, to about two months old, then gradually become more diurnal in habits. (J469.530.w1)

SPEED OF MOVEMENT:

General Information

• The North American leporids are able to escape predators by taking instant flight at high speed. (B430.w2)
• Leporids can run at speeds of up to 80 km/hr. (B147)
• Jack rabbits " run rapidly and for greater distances than the true rabbits (Sylvilagus) that occupy much the same range. Unlike the latter, jack rabbits make rather long, high leaps." (B147)

Specific Lepus californicus Information

• If undisturbed, move slowly with the ears often partly lowered and the tail generally held up over the back. (J469.530.w1)
• Can run at speeds of up to 64 km/h. (J469.530.w1)
• A loping hare hopped at a rate of 218 hops per minute; each hop takes it about 3 m, giving a speed of more than 650 metres per minute. (J469.530.w1)
• Higher observation hops take three times as long as normal hops and reach about 1.1 m high. (J469.530.w1)

NAVIGATION: --

General Habitat Type

Notes

• Most Lepus species live in open grassy habitats. (B147, B285.w5c)
• Jackrabbits tend to be found in areas of sparse vegetation. (B147)

Specific Lepus californicus Information

• It is thought that this species is more able to adapt to habitat changes than others such as Lepus callotis - White-sided jackrabbit, and as such the Black-tailed jackrabbit has replaced this species in areas of overgrazing. (B147)
• The Black-tailed jackrabbit is found in grassland and steppe habitats. (B51)
• This species is capable of surviving in a wide variety of habitats, ranging from sea level to elevations of 3,800 m. (B430.w2, B605.4.w4)
• Thrives on overgrazed pasture. (B605.4.w4)
• Due to its ability to flee from predators, and hence its lack of need for dense cover, this species is usually found in open pastures and rangelands, or in sites of commercial crops. (B430.w2)
• "The black-tailed jackrabbit favors arid regions and areas of short grass rangeland." (B605.4.w4)
• "Many different vegetation types are used, including sagebrush-creosote bush, mesquite-snakeweed, and juniper-big sagebrush." (B605.4.w4)
• In areas where the distribution of this species overlaps that of the Lepus townsendii - White-tailed jackrabbit, the Black-tailed jackrabbit tends to be found more frequently in sagebrush. (B430.w2)
• "In mountainous habitats, white-tailed jackrabbits predominate on the slopes and ridges and black-tailed jackrabbits are more common on the valley floors." (B430.w2)

Nests / Burrows / Shelters

Notes

• Hares tend to reside in caves or crevices in rocks. (B430.w2)
• Lepus species do not usually dig burrows or live in them, favouring fleeing rather than hiding as a mode of escape. (B147)
• The majority of hares rest underneath vegetation, generally lying within shallow dips in the ground (soil, snow or grass) known as 'forms'. (B147)
• The majority of Lepus species live on the surface, but some do dig burrows or use tunnels and holes made by other animals. (B285.w5c)
• Uses 'shelter forms' (small depressions within the ground or vegetation) to rest in during the day. Or may simply rest next to a plant. (B430.w2)

Specific Lepus californicus Information

• Black-tailed jackrabbits in captivity have been known to make use of, and even extend, burrows which have been made by tortoises. This is done in order to escape the heat. (B147)
• Builds and uses shelter forms, which are slightly smaller than those of the Lepus callotis - White-sided jackrabbit. (B430.w2)
• Make shelter forms, often 30 -45 cm long and 10 - 20 cm wide; this may be a slight depression or 3 - 11 cm deep; it is usually deepest at the hind quarters. (J469.530.w1)
• May excavate sand horizontally beneath vegetation to make a shelter from the heat. (J469.530.w1)
• Over much of their range, do not use burrows or holes for shelter. (J469.530.w1)
• In the Mojave Desert, may enter burrows for 3 - 5 hours in the afternoon when temperatures exceed 42 °C. (J469.530.w1)
  • When burrows are dug by the jackrabbit they start as shelter forms and are gradually deepened by digging on hot days, until after several days they are long enough to completely enclose the jackrabbit. (J469.530.w1)
• They make use of burrows of Cynomys or Taxidae taxus. (J469.530.w1)
• Females prepare a nest lined with hair for their young. In a ploughed alfalfa field, the nests were sunk into the ground, with only a small opening in the fur lining at the top; this was level with the surrounding ground surface. In areas with hard soil and good vegetation cover, nests were similar to a shelter form, but larger, under brush or a heavy grass clump. (J469.530.w1)

Distribution and Movement (Migration etc.)

Notes

• This species is found in western and central USA, as well as northern Mexico and Baja California. (B147)
• The Black-tailed jackrabbit was introduced to Nantucket Island. (B147)
• This species is found in the following areas: Northern Mexico (Baja California), Oregon, Washington, Southern Idaho, Eastern Colorado, South Dakota, Western Missouri, Northwestern Arkansas, Arizona, and Northern Mexico. (B285.w5c)
• "Hidalgo and S Queretaro to N Sonora and Baja California (Mexico), north to SW Oregon and C Washington, S Idaho, E Colorado, S South Dakota, W Missouri, and NW Arkansas (USA). Apparently isolated population in SW Montana." (B607.w20)
• The Black-tailed jackrabbit is found in central and southwestern USA as well as northern Mexico. (B51)
• "The black-tailed jackrabbit's historical range encompasses an area from the Pacific Ocean on the west to Arkansas and Missouri on the east. In the north it ranges from southern Washington to South Dakota and in the south it is found throughout Baja California and well into south-central Mexico." (B430.w2)
• This species has been successfully introduced into various states in eastern USA, including Massachusetts, Maryland, New Jersey, Virginia and Florida. (B430.w2, B605.4.w4)
• The densest populations of this species are found in the semiarid and arid Western agricultural and range lands. (B430.w2)
• This species was introduced to areas outside its natural range by hunters who hunt the species both for food and sport. (B430.w2)
• The Black-tailed jackrabbit is widespread in central and western USA, though limited in areas into which it has been introduced. (B430.w2)
• This species is widely distributed in the arid Southwest of America. Its range extends from Washington and South Dakota to Baja California and north Mexico. It is also found from the Pacific coast nearly reaching the Mississippi. (B605.4.w4)
• The Black-tailed jackrabbit is thought to be expanding its range due to its ability to survive on overgrazed land, and as such is taking over areas where the Lepus alleni - Antelope jackrabbit reside in the south, and Lepus callotis - White-sided jackrabbit in the south and Northeast. (B605.4.w4)
• The following distributions have been given for the subspecies of Black-tailed jackrabbit:
  • Lepus californicus altamirae (B430.w2, B607.w20) - "narrow strip about 200 miles long on the eastern seaboard of Tamaulipas, Mexico." (B430.w2)
  • Lepus californicus asellus (B430.w2, B607.w20) - "inland central Mexico, mostly in the state of San Luis Potosi and bordering states to the west." (B430.w2)
  • Lepus californicus bennettii (B430.w2, B607.w20) - "narrow strip along the southern coast of California and southward about 200 miles along the west coast of the Baja peninsula." (B430.w2)
  • Lepus californicus californicus (B430.w2) - "most of central and northern coastal California and northward along the coast into southern Oregon." (B430.w2)
  • Lepus californicus curti (B430.w2, B607.w20) - "one island in the Gulf of Mexico off the coast of Tamaulipas." (B430.w2)
  • Lepus californicus depressus (B607.w20) - [no data given]
  • Lepus californicus deserticola (B430.w2, B607.w20) - "throughout the Great Basin of the United States from southern Idaho southward, through much of Utah and Nevada, the eastern part of southern California, and the western half of Arizona, and extending a short distance into Mexico to the Gulf of California." (B430.w2)
  • Lepus californicus edwardsi (B607.w20) - [no data given]
  • Lepus californicus eremicus (B430.w2, B607.w20) - "southeastern quarter of Arizona and southward through the northern half of Sonora, Mexico." (B430.w2)
  • Lepus californicus festinus (B430.w2, B607.w20) - "a small island area in the Queretaro region northeast of Mexico City." (B430.w2)
  • Lepus californicus griseus (B607.w20) - [no data given]
  • Lepus californicus insularis (B51, B607.w20) - [no data given]
  • Lepus californicus magdalenae (B430.w2, B607.w20) - "Magdalena and Margarita islands off the west coast of Baja California Sur, Mexico." (B430.w2)
  • Lepus californicus martirensis (B430.w2, B607.w20) - "most of the northern two-thirds of the Baja Peninsula, Mexico." (B430.w2)
  • Lepus californicus melanotis (B430.w2, B607.w20) - "Nebraska, Kansas, and Oklahoma, and portions of the adjoining states, including most of northern Texas." (B430.w2)
  • Lepus californicus merriami (B430.w2, B607.w20) - "southeastern Texas and southward about 322 km (200 miles) into the states of Coahuila, Nuevo Leon, and Tamaulipas, Mexico." (B430.w2)
  • Lepus californicus micropus (B607.w20) - [no data given]
  • Lepus californicus richardsonii (B430.w2, B607.w20) - "small inland area in south-central California." (B430.w2)
  • Lepus californicus sheldoni (B430.w2, B607.w20) - "Carmen Island, off the east coast of Baja California Sur in the Gulf of California." (B430.w2)
  • Lepus californicus texianus (B430.w2, B607.w20) - "New Mexico, western Texas, and southward into the states of Chihualina, Coahuila, Durango, and Zacatecas, Mexico." (B430.w2)
  • Lepus californicus tularensis (B607.w20) - [no data given]
  • Lepus californicus vigilax (B607.w20) - [no data given]
  • Lepus californicus wallawalla (B430.w2, B607.w20) - "eastern Oregon and into far northeastern California and the northwestern corner of Nevada." (B430.w2)
  • Lepus californicus xanti (B430.w2, B607.w20) - "extreme southern portion of the Baja Peninsula, Mexico." (B430.w2)

Geographic Sympatry

• This species lives in sympatry with Lepus townsendii - White-tailed jackrabbit. (B430.w2)

Species variation

Notes

Specific Lepus californicus Information

Currently recognised subspecies include:

• Lepus californicus californicus: including Lepus californicus bennettii, Lepus californicus martirensis, Lepus californicus richardsonii, Lepus californicus tularensis, Lepus californicus vigilax.
• Lepus californicus deserticola: including Lepus californicus depressus; Lepus californicus wallawalla.
• Lepus californicus insularis: including Lepus californicus edwardsi.
• Lepus californicus magdalenae: including Lepus californicus sheldoni; Lepus californicus xanti.
• Lepus californicus melanotis: including Lepus californicus altamirae; Lepus californicus curti; Lepus californicus merriami.
• Lepus californicus texianus: including Lepus californicus asellus; Lepus californicus eremicus; Lepus californicus festinus; Lepus californicus griseus; Lepus californicus micropus.

NB: names in non-bold font are reported as synonyms for that particular subspecies from the reference B607.w20.

• These subspecies are considered in two main groups, separated by the Colorado River. "A conservative view would use L.c.californicus for the western populations and L.c.texianus for the eastern ones." (B605.4.w4)

Previously recognised subspecies include:

• Lepus californicus bennettii. (B605.4.w4)
• Lepus californicus californicus. (B430.w2, B605.4.w4)
• Lepus californicus martirensis. (B605.4.w4)
• Lepus californicus richardsonii. (B605.4.w4)

Conservation Status

Notes

WILD POPULATION - IMPORTANCE: 

Specific Lepus californicus Information

• Locally common. (B285.w5c)

• Common to abundant. (B430.w2)

GENERAL LEGISLATION: --

CITES LISTING: --

RED-DATA LIST STATUS: 

Specific Lepus californicus Information

• IUCN - Lower Risk (least concern). (W2.Apr08.w8)

THREATS: --

PEST STATUS / PEST POPULATIONS:  

Specific Lepus californicus Information

• Due to its high population densities and its diet, this species can damage crops, thus making it a serious agricultural pest in some areas. Rabbit drives were used in the 1800s and early 1900s as a means of controlling population numbers, with up to 6,000 jackrabbits being killed per day. (B430.w2)
• In agricultural areas of California, this species is considered a pest as they can damage crops and fruit trees. (B605.4.w4)
• "Today, sport hunting, pest control and better farm management apparently prevent serious outbreaks of black-tailed jackrabbits. This species is expanding in range and conservation of the white-sided L.callotis [Lepus callotis - White-sided jackrabbit], antelope [Lepus alleni - Antelope jackrabbit] and white-tailed jackrabbits [Lepus townsendii - White-tailed jackrabbit] may require some reduction in competition from this more adaptable hare." (B605.4.w4)

CAPTIVE POPULATIONS: --

TRADE AND USE:

Specific Lepus californicus Information 

• This species is hunted both for food and sport, and as a result of this, the Black-tailed jackrabbit has been introduced to areas outside its natural range. (B430.w2)
• Large numbers of jackrabbits were killed by farmers in the late 1800s, as a means of protecting crops, with some of the rabbits were sold to markets in the east. (B605.4.w4)