Lepus townsendii

Geographic Range

White-tailed jackrabbits are found throughout west-central Canada and the United States with an elevation span of 40 to 4,300 m. They range from the Great Plains of Saskatchewan and Alberta east to extreme southwest Ontario down into Wisconsin and across the continent to the Rocky Mountains with a southern limit in central California (Wilson and Ruff, 1999). There has been a noted range reduction from the south east over the past half-century, notably in Kansas, due to habitat alteration from increased agriculture and competition from the sympatric black-tailed jackrabbit ( Lepus californicus ). An accompanying range increase to the north has been observed over time (Kim, 1987).

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

White-tailed jackrabbits prefer open grasslands but thrive in pastures and fields. This species can also be found in forested areas up to high alpine tundra, from 40 to 4300 meters elevation.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial

• Terrestrial Biomes
• desert or dune desert or dune
• savanna or grassland savanna or grassland
• forest forest
• mountains mountains

• Other Habitat Features
• agricultural agricultural

Physical Description

The pelage of Lepus townsendii varies with season and habitat. The upper parts range from yellowish to grayish brown in colour, with white or grey on the underside. The throat and face are somewhat darker with coarser hair. In the northern extent of the range where there is significant snow fall during the year, a pure white colouration is attained with the possibilty of a buffy tint on the face, ears, feet and back. A slight change may be noted in the more southern range where only the sides of the animal become white while the back retains a more buffy-grey tinge. An early to late spring moult reverses this process. As the common name indicates, the tail is always white which may possess a buffy dorsal stripe. Ears of this jackrabbit are rimmed in white and tipped in black year round. The juvenile pelage is similar but paler in colour with more under fur and less developed course guard hairs (Kim, 1987).

White-tailed jackrabbits have a number of other distinct morphological characters which reflect adaptation to their environment and ecology. Enormous ears equipped with generous blood flow are used for heat dissipation in the warmer portions of the range, while they also provide an excellent means of predator detection. L.townsendii have large hind legs which facilitate high jumps and quick escapes from predators (Forsyth,1999). The dental formula is 2/1 0/0 3/2 3/3 =28 with huge upper insicors for nipping plants (Chapman et al.,1982)

Though females are slightly larger in size, there is no other apparent sexual dimorphism (Kim, 1987).

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

• Sexual Dimorphism
• female larger

Reproduction

Three to five males may pursue one female concurrently during mating season, leading to aggresive charging among them. The courting behaviour of white-tailed jackrabbits consists of a series of aggresive charges and jumps. Circling between male and female lasts from 5-20 minutes and is followed by copulation.

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

The breeding season of white-tailed jackrabbits lasts from February to July with a peak from March to June. Ovulation is induced, requiring copulation or suitable stimulation. (Chapman et al., 1982). One to four litters with from 1 to 11 (averaging 4 to 5) young are born each year. A maximum of one litter is produced in more nothern climates. The gestation period is commonly reported as 42 days but this length varies, possibly due to altitude and habitat (Kim, 1987). This species exhibits breeding synchrony with male spermatogenesis and a postpartum estrus that facilitates conception soon after birth of young (Kim, 1987).

At birth the young weigh approximately 90-100 grams, have open eyes, full fur, and limited mobility within half an hour. The young begin to forage at approximately 2 weeks of age and are fulled weaned at one month. Sexually maturity is reached by 7 or 8 months though there is little evidence of reproduction until the spring following their birth.

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

Female L. townsendii nurse and care for their young for about 1 month. Females often create nests for the protection of their young from dried grass, leaves, and hair. Young are born fully furred and are capable of some level of mobility shortly after birth.

• Parental Investment
• precocial precocial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • female
• pre-weaning/fledging
  • provisioning
    • female

Lifespan/Longevity

Lepus townsendii lives to approximately 8 years of age in the wild.

Behavior

Like most mammals, white-tailed jackrabbits are nocturnal, feeding mainly from sunset to sunrise. During the day they rest in shallow forms which are dug into the earth 10-20 cm in depth and are usually under some form of plant cover. Elaborate and well travelled trails may be observed that connect forms between often visited feeding sites. In winter snow, forms are replaced by cave-like structures joined with many connecting tunnels.

Though large groups of white-tailed jackrabbits have been observed during extreme winter cold or in areas of abundant food, they are the least social of all hares (Kim, 1987). Only during the breeding season do small groups of 3 to 4 individuals form for courting behaviours. Nests are built by females and lined with fur. Though they are similar in shape to forms, nests are usually under dense cover. (Kim, 1987).

Lepus townsendii can run up to 55 km/hr and bound 5m into the air.

In arid regions, white-tailed jackrabbits excrete a nearly dry feces as a means of water conservation (Chapman et al., 1982). Heat is dissipated through large ears and voluntary hyperthermia has been observed with the internal body temperature rising to over 41°C at the hottest point in the day (Forsyth, 1999).

• Key Behaviors
• cursorial
• terricolous
• saltatorial saltatorial
• nocturnal nocturnal
• motile motile
• sedentary sedentary
• solitary solitary

Home Range

The home ranges of L. townsendii are poorly studied but believed to be approximately 2 to 3 km in diameter never straying far from forms and known trails.

Communication and Perception

These animals generally make no vocalizations, but will scream if caught or injured (Banfield, 1974). They are likely to rely extensively on their acute hearing and sense of smell to perceive their environment, but also have good vision and whiskers that help them in navigating and finding food. Like most mammals, they probably also rely extensively on chemical cues for communicating reproductive condition.

• Communication Channels
• acoustic acoustic
• chemical chemical

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

Food Habits

White-tailed jackrabbits are strict herbivores. They feed on grasses, forbs, and shrubs in varying amounts. In the summer months, when many succulent plants are readily found, L. townsendii feeds on flora such as clover ( Trifolium sp. ) and dryland sedge ( Carex obtusata ). As the winter months approach, white-tailed jackrabbits turn to the bark of shrubs such as Parry's rabbitbrush ( Chrysothamnus parryi ) and plants like alfalfa ( Medicago sativa ) that are exposed through the snow. Winter wheat ( Triticum aestivum ) and western wheat grass ( Agropyron smithii ) are also imporant parts the diet (Kim, 1987 and Chapman et al., 1982). This species has been known to winter in barns and feed extensively on the hay found inside (Banfield, 1974). White-tailed jackrabbits are generally voracious eaters and captive specimens have been known to eat as much as .5 kg of plant matter daily (Kim, 1987).

• Primary Diet
• herbivore herbivore
  • folivore folivore

Predation

Lepus townsendii is a favorite prey item of animals such as red fox, grey fox, coyote, bobcat, cougar, badger, snakes, owls, eagles, and many species of hawks. The general method of predator avoidance is to lie perfectly still in the form, relying on their cryptic coloration to avoid detection, with large ears pointed slightly up for predator detection. Jackrabbits may attempt to slink off silently but will bound away with surprising speed and height when surprised. Zig-zag patterns as well as proficient swimming have been observed in predator escapes.

• Anti-predator Adaptations
• cryptic cryptic

Ecosystem Roles

White-tailed jackrabbits are an important prey source for medium to large sized predators in the ecosystems in which they live. They also impact vegetation community composition through their grazing activities.

Economic Importance for Humans: Positive

White-tailed jackrabbits were a significant food source for early settlers of North America and continue to be a year round game animal. Their pelts were once highly prized and widely used in the commercial fur industry.

• Positive Impacts
• food food
• body parts are source of valuable material

Economic Importance for Humans: Negative

White-tailed jackrabbits are often viewed as a threat by farmers as they can destroy crops, eat hay stores, and girdle trees (Chapman et al., 1982). Because of low population densities and grassland preferences, the impact of L. townsendii on argriculture is usually small. (Banfield, 1974).

• Negative Impacts
• crop pest

Conservation Status

White-tailed jackrabbits are abundant through most of their range and have no special conservation status. They are considered "least concern" by the IUCN. The subspecies Lepus townsendii townsendii is considered a mammal of special concern in California, where populations have declined dramatically, probably as a result of competition with livestock and overgrazing by livestock.

Other Comments

Two sub-species of Lepus townsendii are recognized with L. t. campanius occuring to the east of the Continental Divide and L. t. townsendii occuring to the west. Though there is little difference between the two, L. t. campanius is slightly larger and some subtle pelage variation is observed (Kim, 1987).

Lepus townsendii acquired its name from J.K. Townsend, who collected the type specimen (Kim, 1987).

Additional Links

Encyclopedia of Life

Contributors

Tanya Dewey (editor), Animal Diversity Web.

Anna Gosline (author), University of Toronto.

References

American Society of Mammalogists, 2009. "Mammals of California" (On-line). American Society of Mammalogists, State lists. Accessed July 27, 2009 at http://www.mammalsociety.org/statelists/camammals.html .

Banfield, A. 1974. The Mammals of Canada . Toronto: University of Toroto Press.

Chapman, J., J. Dunn, R. Marsh. 1982. Lepus townsendii. Pp. 124-137 in Wild Mammals of North America: Biology, Management and Economics . Baltimore: Johns Hopkins University Press.

Forsyth, A. 1999. Mammals of North America . Ontario: Firefly Books.

Lim, B. 1987. Lepus townsendii. Mammalian Species , 288: 1-6.

Wilson, D., S. Ruff. 1999. Smithsonian Book of North American Mammals . Washington: Smithsonian Institution Press.