Mountain cottontail | |
---|---|
![]() | |
Sylvilagus nuttallii at the Hanford Site, Washington | |
Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Order: | Lagomorpha |
Family: | Leporidae |
Genus: | Sylvilagus |
Species: | S. nuttallii |
Binomial name | |
Sylvilagus nuttallii (Bachman, 1837) | |
Subspecies [2] | |
| |
![]() | |
Mountain cottontail range | |
Synonyms [3] | |
Synonyms
|
The mountain cottontail or Nuttall's cottontail (Sylvilagus nuttallii) is a species of cottontail rabbit in the family Leporidae found in western Canada and the United States. It is a medium- to small-sized rabbit with pale brown fur, white undersides, a two-colored tail, and black-tipped, rounded ears with densely-furred insides. The mountain cottontail appears largely among coniferous forests in mountainous regions, including the slopes of the Rocky Mountains and the Cascade-Sierra Nevada mountain ranges, and adapts to a variety of elevations and vegetation. Its diet is made up of various grasses, shrubs, and sagebrush, as well as twigs, bark or fungi in lesser amounts or when foliage is scarce.
Sylvilagus nuttallii was first described by John Bachman in 1837 as Lepus nuttallii, "Nuttall's Little Hare". It was named after the English botanist and zoologist Thomas Nuttall, who collected the type specimen. Its type locality was originally noted as "west of the Rocky Mountains [...by] streams which flow into the Shoshonee and Columbia Rivers". [4] Naturalist Edward William Nelson clarified this locality in 1909 to be "eastern Oregon, near mouth of Malheur River", and the later naturalist Vernon Orlando Bailey described it in 1936 as "near Vale". [2] Being the smallest of the known "true hares" at the time, it was noted as bearing resemblance to the American pika, [5] then known as a member of the hares with the scientific name Lepus (Lagomys) princeps. [6] The description was provided in an illustrated overview of the hares then known to inhabit the United States and Canada; the illustrations were provided by painter and scientific illustrator Maria Martin, Bachman's sister-in-law. [7] The mountain cottontail was first placed in the genus Sylvilagus by Marcus Ward Lyon Jr. in 1904, who used a method based on skeletal characteristics to classify the known lagomorphs (then known as members of order Duplicidentata). [8]
Based on nuclear and mitochondrial gene analysis, it is estimated to have first emerged roughly 5 million years ago, in the early Pliocene. [9] However, fossils of the species, which have been found only in the caves of Utah and Texas, date back to only 35,000 years before present. [10]
The mountain cottontail has 3 subspecies: [2]
Each subspecies may constitute a separate species. [1] However, this separation was only based on a study of dental characteristics; further studies on genetic and morphological traits have not been completed to make more definitive recommendations. [10] The mountain cottontail's diploid chromosome number is 42, [10] a number shared by some but not all members of the genus Sylvilagus . [15] [16] The species is most closely related to the desert cottontail (Sylvilagus audubonii), with which it forms a clade. [17] Its next closest genetic relatives are the swamp rabbit (S. aquaticus) and marsh rabbit (S. palustris). [9]
Sylvilagus nuttallii is medium to small-sized rabbit, having a head and body length of 11 to 15 in (29 to 39 cm), though among cottontail rabbits it is relatively large. The hind legs are long; the feet are densely covered with long hair and measure from 3.1 to 4.1 in (80 to 103 mm). Ears are relatively short (2.1–3.9 in (54–100 mm)) and have rounded tips; the insides are densely furred. [12] The tail, dark on top and white underneath, measures from 1.2 to 2.4 in (3 to 6 cm). It has pale brown fur on the back, a distinct pale brown nape on the back of the head, black-tipped ears, a white-grey tail, and a white underside. [10] The brown nape on the back of the head is a smaller size from than that of the snowshoe hare, helping to distinguish the two separate species from each other. Additionally, contrasting with the snowshoe hare's long hops, the mountain cottontail takes distinctively short leaps. In examining the tracks left by both species in snow, those of the snowshoe hare are much larger, with a splayed shape. [18] Like other leporids, it has a dental formula of 2.0.3.31.0.2.3 × 2 = 28. Its whiskers can be either totally or partially white. [19]
Sylvilagus nuttallii is generally confined to the intermountain area of North America, especially the Western United States. It appears from the Canadian provinces of Alberta and Saskatchewan, just north of the United States-Canada border, to the northern parts of Arizona and New Mexico. Laterally, it is known from the foothills of the eastern slopes of the Rocky Mountains and west to the eastern slopes of the Cascade-Sierra Nevada. In southwestern North Dakota, it was once prevalent, but has since been largely replaced by the eastern cottontail (Sylvilagus floridanus). [12] [1] It was once found as far south as Texas, but changing habitat due to climate change has resulted in the species being pushed back; in these more arid regions, the desert cottontail and robust cottontail (S. holzneri robustus) are more prevalent. [10] The three subspecies of mountain cottontail tend to remain separated in geographical terms. [20]
The mountain cottontail has a fairly cosmopolitan distribution, appearing at varying elevations and in regions with different vegetation. It occurs in coniferous forests, including the subalpine zone, [18] living among rocky areas among sagebrush, in shrublands, or in wooded areas. It is more associated with sagebrush in the northern part of its distribution, and more with forests in the south. Occupying habitats elevated above those of lowland leporids, but below most ochotonids and the snowshoe hare (Lepus americanus), its preferred elevation varies based on location: in California, it occurs from 3,900 to 11,320 ft (1,190 to 3,450 m); in Nevada, from 3,900 to 10,400 ft (1,190 to 3,170 m); in Colorado, from 6,000 to 11,480 ft (1,830 to 3,500 m); in Oregon, from 591 to 5,495 ft (180 to 1,675 m); and in Arizona, above 7,500 ft (2,300 m). It is particularly abundant within the Hanford Site. [10]
Sylvilagus nuttallii is not a social species and when not feeding, courting, or mating tends to live a solitary life. Congregations occur on popular feeding grounds. The majority of feeding occurs at dusk and dawn in clearings near cover or in brush. The mountain cottontail is also known to climb juniper trees to feed or drink water. The mountain cottontail spends half of its waking hours feeding. The most common social behavior seen is during reproductive actions or courting. They are not territorial; males typically have a larger home range than females. [19] Though it does not appear to dig its own burrows, it will use those of other animals when faced with a lack of vegetation for shelter. [10]
The rabbits remain active all year. When spooked, a rabbit will run a couple meters then hide and freeze with ears erect; if further pursued the rabbit will hop away in a semicircular path to try and trick the predator. The only behavior to reduce predation is limiting active time to dusk and dawn, and the semicircular path they hop when chased. Predators include coyotes, bobcats, lynxes, martens, crows, ravens, hawks, owls, and rattlesnakes. [22] [23] Though it has been replaced in some regions by the eastern and desert cottontail, [1] it is largely sympatric with the widely-distributed snowshoe hare (Lepus americanus) [18] and the Northern Idaho ground squirrel. [24] Several parasites are known to affect the mountain cottontail, including nematodes, cestodes, and species of Coccidia. [10] It is affected by the tularemia-causing bacterium Francisella tularensis, [25] [26] as well as Rickettsia rickettsii , which causes Rocky Mountain spotted fever. [27]
The diet of the mountain cottontail is primarily made up of sagebrush and varies toward grasses during the spring and summer seasons. [28] It is made up in large part of grasses such as wheatgrasses, needle-and-thread, Indian ricegrass, cheatgrass brome, bluegrasses, and bottlebrush squirreltail. [29] Dependent on the area the diet may include quantities of shrubs such as big sagebrush, rabbitbrush, and saltbushes. Juniper is also a common food source for the mountain cottontail. [28] It is also known to feed on fungi, including truffles, [30] but not as often as does the black-tailed jackrabbit (Lepus californicus). [31] As food sources becomes more limited in the winter months, the diet may turn to more woody plant parts such as bark and twigs. The mountain cottontail, like other lagomorphs, performs cecotrophy. [19] It is seen more often in sites grazed by horses than those where horses have been removed, a behavior not often seen in similar granivorous species. [10]
The nest of S. nuttallii is reported to be a cup-like cavity lined with fur and dried grass. The top of the nest is covered with fur, grass, and small sticks, probably placed there by the female. The average fetal sex ratio in Oregon was 1 male to 1.05 females; the adult sex ratio was 1 male to 1.18 females. [12] Depending on location, the breeding season will vary during the spring and summer seasons, through February to July, and possibly occurs later in warmer climates. [28] Gestation lasts 29 days on average in the mountain cottontail, and results in a litter of 3 to 4 young; 3.5 litters are produced annually on average within the 4-month breeding season. It reaches sexual maturity at roughly 3 months old. [32] The number of litters and young produced varies by location; in California and Nevada, the average litter size is around 6.1, 4.7 for rabbits in Washington and Oregon, and 2.0 for those in British Columbia. [12] The young are altricial, having a weaning period of one month. [10]
Aside from predators, parasites and diseases, Sylvilagus nuttallii is threatened by competition from other leporids, [1] climate change, and habitat fragmentation. It is commonly hunted for sport, as well as for food. Displacement in North Dakota by the eastern cottontail has led to the mountain cottontail being considered as "presumed extirpated" within the state. Its habitat within Canada is threatened by agricultural and human settlement expansion. [10]
Sylvilagus nuttallii is considered by the International Union for Conservation of Nature to be a least-concern species, though it notes that the overall population of it and several other members of Sylvilagus appears to be decreasing. As game, it is seasonally protected by state wildlife agencies, and the species is being monitored. [1] As individually monitored by each state, its NatureServe conservation status varies: in Arizona and British Columbia, it is considered "vulnerable"; in New Mexico, Oregon, South Dakota, Montana, and Saskatchewan it is "apparently secure", and it is "secure" across the rest of its range. The species occurs in several protected areas. Given the species' wide distribution, it may have greater ability to survive changes in environment. However, should the species be divided into three along subspecies lines, the resulting clades will be more constrained and less genetically diverse, and may have greater need for conservation measures. [10]
{{cite journal}}
: CS1 maint: multiple names: authors list (link)