Lepus callotiswhite-sided jackrabbit

Geographic Range

Lepus callotis ranges from southern New Mexico to northwestern and central Mexico. (Best and Henry, 1993; Hall, 1981)

Habitat

Lepus callotis inhabit high plateaus at high elevations, including the grassy plains of southwestern New Mexico and the open plains of the southern Mexican tableland. They avoid hilly areas by selecting for level grassland topography with few shrubs. ("Grizmek's Encyclopedia of Mammals, Volume 4", 1990; Best and Henry, 1993)

Physical Description

Lepus callotis body length ranges from 432 to 598 mm, tail length from 47 to 92 mm, hid foot length 118 to 141 mm, and ear length from 108 to 149 mm. The forepaws have five toes while the back paws have four. All toes end in sturdy claws. Some sexual dimorphism is present; females are generally larger than the males.

The dorsal pelage of Lepus callotis is short and coarse. The color is pale ochraceous-cinammon color heavily mixed with black. The underparts are white with traces of colored patches in front of the thighs. The tail has black hairs tipped with white on the upper surface and is all white on the underside. The sides are distinguishable from other Lepus species in that they are pure white. The rump and thighs are also white and lined with a few black hairs. A median black line concealed by sooty, brownish, and white-tipped hairs divides the rump. The limbs are white, but their outer surface is stained a buffy color. The gular pouch is also buffy while the sides of the neck and shoulders become more ochraceous in color. The head is a cream buff color, mixed with black, with whitish areas around the sides of the eyes. The ears are covered with short yellowish brown hairs that are mixed with black anteriorly and white posteriorly. The apex of the ear is white-tipped. Below the apex of the ear is a tuft of black hair. The long fringes on the anterior edge of the ear are ochraceous buff while the fringes of the tip of the ear and posterior edge are white. The inner surface of the ear is almost bare except for a dusky spot on the posterior border. The nape is ochraceous buff in color.

The winter pelage of Lepus callotis is iron gray on the rump, back, and outside of the hind legs. The front of the hind legs and the tops of the feet are white. The front of the fore legs and top of the forefeet range from a pale gray to a dull iron-gray. The median black line of the rump is not strongly distinguishable and does not extend much further than the base of the tail. The top, sides, and tip of the tail are black while the underside is two-thirds white and one-third black. The top and sides of the head and back are dark-pinkish buff overlaid with black. The nape is usually black. The ears are dark bluff, black, and white. The front border of the ears are fringed with buff or ochraceous buff hairs, and the posterior border and tip are white. The underside of the neck is dark grayish bluff and the remaining underparts, including the flanks, are white. ("Grizmek's Encyclopedia of Mammals, Volume 4", 1990; Best and Henry, 1993; Hall, 1981)

  • Sexual Dimorphism
  • female larger
  • Range mass
    2 to 3 kg
    4.41 to 6.61 lb
  • Range length
    432 to 598 mm
    17.01 to 23.54 in

Reproduction

The breeding season of Lepus callotis is a minimum of 18 weeks, occurring from mid-April to mid-August. The average number of young per litter is 2.2. The young tend to have a soft, woolly coat in early life and attain sexual maturity at a rapid rate. Breeding in Lepus does not begin within the first calendar year following their birth. ("Grizmek's Encyclopedia of Mammals, Volume 4", 1990; Best and Henry, 1993; Nowak, 1999)

  • Breeding season
    Breeding occurs from mid-April to mid-August.
  • Average number of offspring
    2.2

Behavior

Most activity of Lepus callotis occurs during the night or at dusk, particularly on clear nights with bright moonlight. Their activity may be limited by cloud cover, precipitation, and wind, but temperature has little effect. The escape behavior consists of alternately flashing its white sides when running away. Lepus callotis, when escaping, make rather long, high leaps. When startled by a or alarmed by a predator, they leap straight upwards while extending the hind legs and flashing the white sides. In its resting position, a white-sided jackrabbit is camouflaged with its surroundings. The long hind legs and feet are adapted for speed, giving the animal lift and an ability to run in a zigzag fashion that surpasses its pursuers. The long ears serve to locate sound as well as regulate temperature when they are raised like a fan to catch passing breezes in hot conditions. The eyes, like those of most nocturnal animals or animals that are active at dusk, are laterally arranged, giving them a complete field of vision (360 degrees). As a result, approaching danger can be perceived in advance.

A conspicuous trait of Lepus callotis is its tendency to occur in pairs, usually one male and one female. They exhibit a pair bond that is most evident during the breeding season. After establishment of the pair bond, the male defends the pair from other intruding males. The purpose of such pair bonds may be to keep the sexes together in areas of low density. The members of the pair are usually within 5 meters of each other and run together when approached by intruders. The pair bond may not be broken during pregnancy.

Lepus callotis construct and utilize shelter forms averaging 37 cm in length, 18.3 cm in width, and 6.3 cm in depth. The shelter form is usually located in clumps of grass and surrounded by dense stands of tabosagrass. Lepus callotis may also occupy underground shelters, but this behavior is rare. Lepus callotis forages by chewing and pulling grass blades near the ground until they are either uprooted or broken off. The food is ingested by chewing the grass that is sticking out of the mouth, with the head raised and the body sitting in a crouched position. The forepaws are not used in feeding except to brace Lepus callotis against the ground as the grass is bitten off or uprooted. When eating sedge nutgrass, however, the forepaws are used to excavate the bulbous tubers, leaving behind oval foraging depressions in which fecal pellets are often deposited. ("Grizmek's Encyclopedia of Mammals, Volume 4", 1990; Best and Henry, 1993; Nowak, 1999)

Communication and Perception

Lepus callotis has three types of vocalizations. The alarm or fear reaction consists of a high-pitched scream. Another sound, emitted by males in a pair when approached by an outside intruding male, is a series of harsh grunts until the intruder leaves or is chased away. A third vocalization, consisting of a trilling grunt is heard during the sexual chase of Lepus callotis, however, it is not known which member of the pair makes this sound. ("Grizmek's Encyclopedia of Mammals, Volume 4", 1990; Best and Henry, 1993; Nowak, 1999)

Food Habits

The diet of Lepus callotis consists primarily of grasses including buffalograss, tabosagrass, fiddleneck, wolftail, blue grama, vine mesquite, ring muhly, wooly Indian wheat, and Wright buckwheat. The significant non-grass item found in their diets was sedge nutgrass. (Best and Henry, 1993; Nowak, 1999)

  • Plant Foods
  • leaves
  • wood, bark, or stems

Economic Importance for Humans: Positive

In general, various species of Lepus are used as food, and their fur may be used in manufacturing felt or for trimming gloves and other garments. No specific economic importance is noted for Lepus callotis. ("Grizmek's Encyclopedia of Mammals, Volume 4", 1990; Nowak, 1999)

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

Economic Importance for Humans: Negative

Species of Lepus that live in settled areas are often considered pests because of the damage they to crops, orchards, and young forest trees. No specific adverse economic effects are noted for Lepus callotis (Grizmek 1990; Nowak 1999).

Conservation Status

Lepus callotis is considered endangered throughout its range in Mexico and southwestern New Mexico. Lepus callotis commonly comes into contact with agriculture. As a result, the overgrazing of domestic livestock may be one of the factors contributing to its decline and the apparent replacement by Lepus californicus, which has been highly adaptable to these habitat changes. Prospects for the survival of Lepus callotis in many parts of its range are considered poor. (Best and Henry, 1993; Nowak, 1999)

Contributors

Aarti Dharmani (author), University of Michigan-Ann Arbor, Phil Myers (editor), Museum of Zoology, University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

saltatorial

specialized for leaping or bounding locomotion; jumps or hops.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5? N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

visual

uses sight to communicate

viviparous

reproduction in which fertilization and development take place within the female body and the developing embryo derives nourishment from the female.

young precocial

young are relatively well-developed when born

References

1990. Grizmek's Encyclopedia of Mammals, Volume 4. New York: McGraw Hill Publishing Co..

Best, T., T. Henry. 1993. Mammalian Species No. 442. The American Society of Mammalogists.

Hall, E. 1981. The Mammals of North America, Second Edition, Volume I. New York, Chichester, Brisbane, & Toronto: John Wiley & Sons.

Nowak, R. 1999. Walker's Mammals of the World, Sixth Edition, volume II. Baltimore & London: The Johns Hopkins University Press.