The white-sided jackrabbit (Lepus callotis), also known as the Mexican hare or the beautiful-eared jackrabbit, is a jackrabbit found in a limited range in North America, from southern New Mexico to northwestern and central Mexico. The animal is considered threatened in New Mexico, with its numbers in decline in recent years; its presence is uncertain in Arizona.
Taxonomy and etymology
The white-sided jackrabbit was first described in 1830 by the German naturalist Johann Georg Wagler. He gave it the scientific nameLepus callotis and noted that it was smaller than the mountain hare (Lepus timidus) but had longer ears.[3] The species' type locality was given as simply "Mexico"; this was clarified as the southern end of the Mexican Plateau by American naturalist Edward William Nelson in 1909.[4] Nothing is known about the white-sided jackrabbit's holotype.[5] Its genus name, Lepus, is Latin for 'hare'. The species name, callotis, is derived from Greek, being a combination of the words call, 'beautiful', and ot, 'ear'.[6]
Common names for this species include the beautiful-eared jackrabbit, Gaillard jackrabbit (referring to the subspecies Lepus calloris gallardi),[7] snow sides,[8] and in Spanish, liebre torda or liebre pinta.[9]
There are two recognized subspecies of the white-sided jackrabbit:[6]
Lepus callotis callotisWagler, 1830. Synonymous with Lepus mexicanus(Lichtenstein, 1830) and Lepus nigricaudatus(Bennett, 1833).
The subspecies L. c. gallardi is distinguished from the nominate subspecies by a paler fur coat and preference for colder grassland habitats with abundant buffalo grass.[9] Another population of hares, the Tamuliapas jackrabbit (Lepus altamirae), has variously been considered a subspecies of either the white-sided jackrabbit or the black-tailed jackrabbit (L. californicus) up until 2016.[10]
Distribution and habitat
The white-sided jackrabbit is found from the south of New Mexico down to the Mexican state of Oaxaca. The hare's range extends throughout the central highlands of Mexico.[11] It occurs alongside the black-tailed jackrabbit,[11] as well as the antelope jackrabbit (Lepus alleni).[4]L. callotis gallardi is present in isolated regions throughout the species' northern distribution, occurring in New Mexico and the Mexican states of Chihuahua and Durango. Two individuals from this subspecies were seen in Arizona in 1950 near the Huachuca Mountains, but the white-sided jackrabbit's continued presence in this state is uncertain. L. c. callotis is found in a region extending from eastern Durango to northern Guerrero and Oaxaca.[1]
The white-sided jackrabbit inhabits plateaus at high elevations, including the grassy plains of southwestern New Mexico and the open plains of the southern Mexican tableland. It avoids areas of hills or mountains. It prefers level lands full of grasses and also avoids areas with trees and shrubs.
Description
Illustration of the white-sided jackrabbit by Andreas Fleischmann (1811-1878)
The white-sided jackrabbit is a medium-sized hare. Its adult body length ranges from roughly 17 to 24 inches (43 to 60 centimeters) long.[11] Its tail grows to lengths of 1 to 4in (2.5 to 10.2cm). Its legs grow from 4 to 6in (10 to 15cm) in the front and the back legs can grow from 6 to 12in (15 to 30cm) long. The white-sided jackrabbit's ears grow 2 to 6in (5.1 to 15.2cm) when fully grown. The fore paws have five toes while the back paws have four. All toes end in sturdy claws. Some sexual dimorphism is present in this species; females are generally larger than the males.
The dorsal pelage of the white-sided jackrabbit is short and coarse. The color is pale cinnamon 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 species in that they are pure white, the source of their name. 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 surfaces are stained a buff 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 the white-sided jackrabbit 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 fore feet 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.
Like other hares and rabbits, it has a dental formula of 2.0.3.31.0.2.3 × 2 = 28, indicating that it has two pairs of upper and one pair of lower incisors, no canines, three upper and two lower premolars on each side, and three upper and lower molars on either side of the jaw.[12] The bones that enclose the middle and inner ear, the auditory bullae, are large, though slightly shorter in length than a row of the hare's molars. The skulls of both the white-sided and black-tailed jackrabbits are nearly indistinguishable; the two species can only be differentiated by their fur colors, as the white-sided jackrabbit has distinct gray flanks and white ear tips, as well as being more yellow overall. The sympatric antelope jackrabbit can be told apart from the white-sided jackrabbit by its larger body and longer ears.[11]
Behavior and ecology
Most activity of the white-sided jackrabbit occurs during the night or at dusk, particularly on clear nights with bright moonlight. Its activity may be limited by cloud cover, precipitation, and wind, but temperature has little effect. Its escape behavior consists of alternately flashing its white sides when running away. The white-sided jackrabbit, when escaping, makes rather long, high leaps. When startled by or alarmed by a predator, it leaps 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 zig-zag 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 or crepuscular animals, are laterally arranged, giving them a complete field of vision (360°). As a result, approaching danger can be perceived in advance.
A conspicuous trait of the white-sided jackrabbit is its tendency to be found in pairs, usually one male and one female. Its pair bond 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 15–20ft of each other and run together when approached by intruders. The pair bond may not be broken during pregnancy.
The white-sided jackrabbit constructs and uses shelter forms averaging 15in (38cm) in length, 20in (51cm) in width, and 7–8in (18–20cm) in depth. The shelter form is usually located in clumps of grass and surrounded by dense stands of tobosa grass. The white-sided jackrabbit may also occupy underground shelters, but this behavior is rare. It 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 sticking out of the mouth, with the head raised and the body sitting in a crouched position. The fore paws are not used in feeding except to brace against the ground as the grass is bitten off or uprooted. When eating certain nutgrass, however, the fore paws are used to excavate the bulbous tubers, leaving behind oval foraging depressions in which fecal pellets are often deposited.
The white-sided jackrabbit 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 the white-sided jackrabbit, but it is not known which member of the pair makes this sound.
The breeding season of the white-sided jackrabbit typically occurs from mid-April to mid-August, but may begin earlier in mid-March and end as late as mid-October.[13] Adult females will produce three litters every year, yielding one to four young each litter and two on average. Gestation lasts for 42 days.[14] The young are born in burrows, fully furred with a soft, woolly coat.[13]
Human interaction and impact
White-sided jackrabbits are hunted in Mexico for their meat and for sport,[1] particularly in the states of Chihuahua and Zacatecas.[5] A 2011 study by the New Mexico Department of Game and Fish determined that the primary cause of decline of the white sided jackrabbit in New Mexico was due to road kill caused by nighttime US Border Patrol traffic.[15]
Conservation status
The white-sided jackrabbit is considered endangered throughout its range in Mexico, and has been listed as "threatened" by the state of New Mexico since 1975. The population of white-sided jackrabbits in New Mexico has declined from a high of 400 total animals in 1976 down to just 58 in 2010, and from nearly 13,000 across its entire range down to roughly 2,100 in the same time period. Its range frequently overlaps regions that are used for agriculture; the overgrazing of domestic livestock in these regions may be one of the factors contributing to its decline and apparent replacement by the black-tailed jackrabbit (Lepus californicus), which has been highly adaptable to these habitat changes.[1] Other sources of stress on the white-sided jackrabbit include vehicle collisions, feral dogs and other introduced predators, fires, and hunting.[13] It has been considered a vulnerable species by the International Union for Conservation of Nature since 2019. The northern populations of the species are considered more vulnerable to contraction than those in the south.[1] A 2009 petition to provide the species protections under the Endangered Species Act was rejected on the grounds that it was not considered "at risk" in Mexico, despite evidence of it being endangered throughout its entire range. In a 2026 account of the species, authors Consuelo Lorenzo and Arturo Carrillo-Reyes advised that additional research is needed on the species' population dynamics (including the distinctions between subspecies), habitat conditions and alterations, relationships with conspecifics within its range, and how it is impacted by disease outbreaks and climate change. The white-sided jackrabbit's range is predicted to see a reduction of 80% by 2050 due to climate change.[5]
123Lorenzo, Consuelo; Carrillo-Reyes, Arturo (2026). "Lagomorpha". In Monterrubio, C. Lorenzo; Mora, J. M. (eds.). Handbook of the Mammals of Middle and South America. Springer Nature Switzerland. pp.1–12. doi:10.1007/978-3-031-31564-0_17-1.
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