Lepus alleni, Mearns, 1890
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publication ID |
https://doi.org/ 10.5281/zenodo.6625539 |
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DOI |
https://doi.org/10.5281/zenodo.6625470 |
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persistent identifier |
https://treatment.plazi.org/id/03822308-B767-FFD9-FFCB-FEA0F693F08E |
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Carolina |
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scientific name |
Lepus alleni |
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49. View On
Antelope Jackrabbit
French: Lievre dAllen / German: Antilopenhase / Spanish: Liebre antilope
Other common names: Allen's Hare, Allen's Jackrabbit, Blanket Jak, Burro Jack, Jackass Rabbit, Mexican Jackrabbit, Saddle Jack, Wandering Jackrabbit
Taxonomy. Lepus alleni Mearns, 1890 View in CoL ,
“Rillito Station [Pima Co.], Arizona,” USA.
A recent molecular phylogenetic study based on mtDNA suggests that L. californicus might have been isolated in Mexico and diverged into a new lineage. From the original stock ( L. callotis ), one population wasisolated in western coastal plains (L. allent) and a second isolated population was isolated in the Isthmus of Tehuantepec ( L. flavigularis ). Taxonomical analysis of cranial characteristics of subspecies revealed no differences. Insular subspecies might not be distinct from mainland subspecies. In southern Arizona, L. alleni and L. californicus occur sympatrically. As taxonomists are still trying to clarify the species differentiation in Lepus , the subspecific taxonomy is not elaborated yet. The original descriptions of the subspecies are often not very helpful as they are mostly based on few exterior characteristics and small numbers of individuals. It has been shown that the variability is clinal in more careful investigations. Hence, the distinction in subspecies might be arbitrary and unreasonable. Three subspecies recognized.
Subspecies and Distribution.
L.a.alleniMearns,1890—SCArizona(SWUSA)andC&WSonora(NWMexico).
L.a.palitansBangs,1900—SSonora,Sinaloa,extremeSWChihuahua,andNWNayarit(WMexico).
L. a. tiburonensis Townsend, 1912 — Tiburon I in the Gulf of California, Sonora (NW Mexico). View Figure
Descriptive notes. Head-body 550-670 mm, tail 48-76 mm, ear 140-170 mm, hindfoot 127-150 mm; weight 2:7.4-5 kg. The Antelope Jackrabbit has exceptionally large, whitish ears that are nearly naked except for long fringes of white hair on edges. Head has whitish and fulvous tint, mixed with black. Eye rings are white. Dorsal pelage is yellowish brown, mixed with black. Nape is plumbeous. Sides, hips, and rump are pale gray. Ventral pelage, chin, and throat are white. Chest is fulvous, and this color extends backward on lower part of neck. Tail is white and lined above with plumbeous black that extends forward upon rump. Pelage is darker in winter than summer. Subspecies tiburonensis tends to be smaller, with a total length of 500-610 mm. Ears might be more than 210 mm long and more than 100 mm wide, which adds ¢.25% to total surface area of body. Ears are used to dissipate heat in desert climates. Body temperature of the Antelope Jackrabbit averages 37-9°C at ambient temperatures of 3°-25°C. At higher ambient temperatures, body temperature increases as ambient temperature increases and reaches 40-3°C at an ambient temperature of 39°C. Rectal glands secrete orange colored, with a strong musky odor. Their function is unknown, but an individual probably leaves a record in its shelter form or wherever it pauses to sit.
Habitat. Various habitats from sea level (Sonora, Mexico) to elevations of c.1500 m (southern Arizona). In Arizona, Antelope Jackrabbits favored habitats on slopes at moderate elevations where grasses, mesquites ( Prosopis ), and catclaws ( Acacia ), both Fabaceae , are abundant. They also live in desert habitat with little grass, hilly country among scattered oaks ( Quercus , Fagaceae ) and junipers ( Juniperus , Cupressaceae ), and stabilized sand dunes. In Mexico, Antelope Jackrabbits occur in low and open grasslands, open grassy foothill with patches of low bushes, and arid and desert plains. Shelter forms include backing up under clumps of vegetation, a sitting place beside a cactus or mesquite trunk with no shade and no digging or scratching having been made, or a dug out depression in the soil. Antelope Jackrabbits always seek shade in shelter forms during hot seasons. Where the Antelope Jackrabbit and the Black-tailed Jackrabbit ( L. californicus ) occur sympatrically, they often sit together under the same bush or runaway side by side. The Antelope Jackrabbit is more numerous on grassy plains at high elevations; the Black-tailed Jackrabbit is more numerous in mesquite along valley bottoms and on barren chaparral desert.
Food and Feeding. The Antelope Jackrabbit feeds primarily on green grass (45%), mesquite ( Prosopis juliflora, 36%), and succulent cacti (7-8%). Of all cacti species available to it, it forages most on pulps and pods of Opuntia engelmanni ( Cactaceae ). Diet varies with alternating dry and rainy seasons: cacti are increasingly consumed during dry seasons, and grasses are favored after the rainy seasons. The Antelope Jackrabbit seeks minerals by digging and biting soil. There is no evidence that the Antelope Jackrabbit requires free water. Insulation and reflectance of pelage reduce water loss. Seeking shade reduces heat load and waterloss.
Breeding. Reproductive season of the Antelope Jackrabbit extends from late December through September, with pronounced peaks in spring and mid-summer. Mating is promiscuous. Males fight by rearing up on hindfeet and hitting each other vigorously and with great rapidity for several seconds. The silent fight usually ends with the victor pursuing the vanquished. Two copulations in the field have been observed. In one instance, a preceding chase and vigorous combat accompanied by continuous growling took place, and in the other instance, the female chased the male a few meters, uttering a growl or grunt after copulation. Gestation is c.6 weeks. Litters average 1-9 young (range 1-6 young). A female has 3—4 litters/year. Percentages of females pregnant and litter size correlate with rainfall. The female gives birth to precocial young in a nest below ground and lined with her fur. Neonates do not show characteristic white rumps, but one 19day-old young had a white rump. The mother returns at night to nurse her young. Length of parental care is short, and young become independent in a matter of days. Young are slightly darker than adults. Breeding age of Antelope Jackrabbits is attained during the second year of life under favorable conditions. Adult sex composition in one population was 47-5% males and 52-5% females.
Activity patterns. The Antelope Jackrabbit is nocturnal and crepuscular, but diurnal activity is commonly recorded. Shelter forms are used for resting during the day.
Movements, Home range and Social organization. The Antelope Jackrabbit might be the fastest species of Lepus , with running speeds of up to 72 km/h. It leaps over bushes higher than 1 m and fences higher than 1-5 m with little change in stride. One leap of 7 m was recorded. When Antelope Jackrabbits start to run, they make 4-5 long hops on their hindlegs alone, like a kangaroo, and then revert to usual locomotion. When threatened by a predator, they flash their white areas on their rumps and sides by pulling up skin by special muscles. Where food and shelter are separated, daily movements occur. Trips of 16 km from desert to feed on alfalfa have been recorded. Average home range size is 642-8 ha.
Status and Conservation. Classified as Least Concern on The IUCN Red List. The insular subspecies tiburonensis is endemic and rare and is currently granted “special protection” under Mexican Official Norm NOM-059-SEMARNAT-2001 because it is an insular and endemic species. The Antelope Jackrabbit is widespread, with a stable population. Declines in southern Arizona have been reported. The Antelope Jackrabbit has almost disappeared due to rabbit plague near Organ Pipe Cactus National Monument, Arizona, although it was once rather common. Expanding agriculture and resulting habitat alteration and overgrazing by livestock are threats to the Antelope Jackrabbit. Overgrazing by livestock favors the Black-tailed Jackrabbit. Additional threats to the Antelope Jackrabbit are hunting, human perturbations, predation by introduced species, habitat fragmentation, and human-induced fires.
Bibliography. Allen (1906a), AMCELA, Romero & Rangel (2008h), Angermann (2016), Armstrong & Jones (1971), Best & Henry (1993a), Brown & Krausman (2003), Burt (1938), Chapman et al. (1983), Claire (1978), Dawson & Schmidt-Nielsen (1966), Dice & Blossom (1937), Dixon et al. (1983), Doutt (1934), Flux & Anger mann (1990), Garland (1983), Ghobrial & Nour (1975), Goldman (1951), Hall (1951, 1981), Hoffmann & Smith (2005), Howell (1944), Huey (1942), Lange (1960), Lissovsky (2016), Mearns (1890), Ramirez-Silva et al. (2010), Schmidt-Nielsen et al. (1965), Simmons (1966), Swarth (1929), Swihart (1986), Vorhies (1921).
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