Mountain cottontail

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". 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". Being the smallest of the known "true hares" at the time, it was noted by Bachman as bearing resemblance to the American pika, then known as a member of the hares with the scientific name Lepus (Lagomys) princeps. 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. 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). Based on nuclear and mitochondrial gene analysis, it is estimated to have first emerged roughly , in the early Pliocene. Fossils of the species dating back 35,000years have been found in caves in Utah and Texas. The mountain cottontail has 3 subspecies: • S. n. nuttallii (Bachman, 1837): Nominate subspecies; synonymous with Lepus artemesia (Bachman, 1839) and S. grangeri Lyon, 1904. Range extends along the western part of the species distribution from northern California to British Columbia. • S. n. grangeri (J. Allen, 1895): synonymous with S. n. perplicatus Elliott, 1904. Type locality of Hill City, South Dakota. Range extends from northern Arizona to the Canadian provinces of Alberta and Saskatchewan. • S. n. pinetis (J. Allen, 1894): Type locality within the White Mountains south of Mount Ord. The southernmost of the mountain cottontail subspecies, its range extends from northeastern Arizona to Colorado. Each subspecies may constitute a separate species. However, this separation was based only on a study of dental characteristics; further studies on genetic and morphological traits have not been completed to make more definitive recommendations. The mountain cottontail's diploid chromosome number is 42, a number shared by some but not all members of the genus Sylvilagus. The species is most closely related to the desert cottontail (Sylvilagus audubonii), with which it forms a clade. Its next closest genetic relatives are the swamp rabbit (S. aquaticus) and marsh rabbit (S. palustris). ==Characteristics==

, Colorado. From the back, the colorations of the back of the head and legs are visible. Sylvilagus nuttallii is a medium to small-sized rabbit, with a head and body length of , though among cottontail rabbits it is relatively large. The hind legs are long; the feet are densely covered with long hair and measure from . The ears are relatively short () and have rounded tips; the insides are densely furred. The tail, dark on top and white underneath, measures from . It has pale brown fur on the back, black-tipped ears, a white-grey tail, and a white underside. The back of the head is an orange color, and the legs appear rusty on the outside. It has a distinctive cinnamon-colored ring around the eyes. Its whiskers can be either totally or partially white. Like other leporids, the mountain cottontail has a dental formula of , i.e. two pairs of upper and one pair of lower incisors, no canines, three upper and two lower premolars, and three upper and lower molars on either side of the jaw. The mountain cottontail can be distinguished from other rabbits that share the same habitat by its size and ear shape. It is larger than the pygmy rabbit (S. idahoensis), smaller than the eastern cottontail (S. floridanus), and has shorter, more rounded, and more densely haired ears than the desert cottontail. The snowshoe hare occurs in many of the same geographic regions as the mountain cottontail, but has a gray fur coat that changes to entirely white in autumn and winter. 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. Unlike the snowshoe hare, the mountain cottontail's fur coat does not change with the seasons for camouflage. ==Distribution and habitat==

to suit the changing seasons, and thus it must seek out areas with grassy cover for shelter. ==Behavior and ecology==

Sylvilagus nuttallii is not a social species and tends to live a solitary life. However, congregations do 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, and spends approximately half of its waking hours feeding. The most common social behavior seen is during reproductive actions or courting. It is not territorial. Males typically have a larger home range than females. When there is plenty of cover from dense vegetation, the mountain cottontail rests in shallow depressions or nests in the ground known as forms for shelter. When vegetation is sparse, it will use the burrows of other animals for shelter instead. It does not seem to dig burrows of its own. The rabbits remain active all year. When startled, 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. Predators include coyotes, bobcats, lynxes, martens, crows, ravens, hawks, owls, and rattlesnakes. Though it has been replaced in some regions by the eastern and desert cottontail, it is largely sympatric with the widely distributed snowshoe hare (Lepus americanus) and the Northern Idaho ground squirrel. Several parasites are known to affect the mountain cottontail, including nematodes, cestodes, and species of Coccidia. It is affected by the tularemia-causing bacterium Francisella tularensis, as well as Rickettsia rickettsii, which causes Rocky Mountain spotted fever. Notably, it is susceptible to rabbit hemorrhagic disease virus type 2, which primarily affects the European rabbit (Oryctolagus cuniculus) and some hare species (Lepus spp.). Diet The diet of the mountain cottontail is primarily made up of sagebrush and varies toward grasses during the spring and summer seasons. During these seasons, preferred grasses include wheatgrasses in the genus Agropyron, needle-and-thread, Indian ricegrass, cheatgrass brome, bluegrasses, and bottlebrush squirreltail. Dependent on the area, the rabbit's diet may include shrubs such as big sagebrush, rabbitbrush, and saltbushes. Juniper is also a common food source for the mountain cottontail. It is also known to feed on fungi, including truffles, but not as often as does the black-tailed jackrabbit (Lepus californicus). 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, consumes soft droppings that come directly from the anus in a process known as cecotrophy to supplement its nutritional intake. It is seen more often in sites grazed by horses than those where horses have been removed, a behavior not often seen in similar, seed-eating species. Reproduction , Alberta, Canada The mountain cottontail's nest is a shallow cavity in the ground lined with rabbit fur and dried grass. The female covers the top of the nest with grass, fur, and sticks. Ratios between the sexes varies based on location; on average, the fetal sex ratio is 1 male to 1.05 females, but in Oregon it was measured at 1 male to 1.18 females. 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. 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. 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. The young are altricial (born helpless and blind) and have a weaning period of one month. ==Status and conservation==

Aside from predators, parasites and diseases, Sylvilagus nuttallii is threatened by competition from hares and other rabbits, 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 locally extinct" within the state. Its habitat within Canada is threatened by agricultural and human settlement expansion. Sylvilagus nuttallii is considered by the International Union for Conservation of Nature (IUCN) 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. 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 the ability to survive drastic changes in its 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. ==References==