# Mountain cottontail

The mountain cottontail or Nuttall's cottontail (Sylvilagus nuttallii) is a species of mammal in the family Leporidae. It is found in Canada and the United States.

## Taxonomy

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 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's diploid chromosome number is 42.
Based on nuclear and mitochondrial gene analysis, it is estimated to have first emerged roughly 5 million years ago, in the early Pliocene. 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.
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 within the White Mountains south of Mount Ord. Range extends from northern Arizona to the Canadian provinces of Alberta and Saskatchewan.
* S. n. pinetis (J. Allen, 1894): Type locality of Hill City, South Dakota. 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 only based on a study of dental characteristics; further studies on genetic and morphological traits have not been completed to make more definitive recommendations.

## Characteristics

The mountain cottontail is a small rabbit but its size is relatively large for the genus. Hind legs are long; the feet are densely covered with long hair. Ears are relatively short and rounded at the tips; the inner surfaces are noticeably haired. 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. 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 cottontails take short distinctive leaps.

## Distribution and habitat

Sylvilagus nuttallii is generally confined to the intermountain area of North America, especially the Western United States. It ranges from just above the Canada–US border south to as far north as Edmonton. The hypothesis is the range has expanded further north due to global warming. Arizona and New Mexico, and from the foothills of the eastern slopes of the Rocky Mountains and west to the eastern slopes of the Cascade-Sierra Nevada. It has a large east to west range from the state of South Dakota to California. 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 (S. audubonii) and robust cottontail (S. holzneri robustus) are more prevalent. The three subspecies of mountain cottontail tend to remain separate in geographical terms. Aside from geographical confinement, the mountain cottontail survives in a large range of elevations under 6000 feet and the landscape in which it resides differs in legislation. It is sympatric with Northern Idaho ground squirrels.

## Behavior and ecology

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. 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.
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. 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.

### Diet

The diet of the mountain cottontail is primarily made up of sagebrush and varies toward grasses during the spring and summer seasons. It is made up in large part of grasses such as wheatgrasses, needle-and-thread, Indian ricegrass, cheatgrass brome, bluegrasses, and bottlebrush squirreltail. 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. 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, performs cecotrophy.

### Reproduction

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. 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, having a weaning period of one month.