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Living OrganismsAnimalia / Craniata / Mammalia / Lagomorpha / Leporidae / Sylvilagus / Species

Sylvilagus nuttallii - Mountain cottontail (Click photographs/illustrations for full picture & further details)

 

INDEX - INFORMATION AVAILABLE

GENERAL & REFERENCES

APPEARANCE / MORPHOLOGY

LIFE STAGES / NATURAL DIET / PHYSIOLOGY

BEHAVIOUR

HABITAT & RANGE

CONSERVATION

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General and References

Alternative Names (Synonyms)

  • Nuttall's cottontail. (B51, B285.w5c, B430.w2, B605.5.w5, W2.Apr08.w85)
  • Sylvilagus artemesia. (B607.w20)
  • Sylvilagus nuttalli grangeri. (B607.w20)
  • Sylvilagus nuttalli perplicatus. (B607.w20)
  • Sylvilagus nuttalli pinetis. (B607.w20)
  • Sylvilagus nuttallii grangeri. (B430.w2, B605.5.w5)
  • Sylvilagus nuttallii nuttalli. (B430.w2, B605.5.w5)
  • Sylvilagus nuttallii pinetis. (B430.w2, B605.5.w5)

Names for new-borns / juveniles

Names for males

Names for females

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General Appearance

Adult:

Specific Sylvilagus nuttallii Information

  • This is a medium-sized species. (B430.w2)
  • Small to medium in size. (B605.5.w5)
  • The Mountain cottontail is a greyish cottontail with a white underside; the tail has a dark grizzled upperside and white underside, the whiskers are white or partly so, never black. It has relatively short ears which are rounded at the tip and have hairy inner surfaces. (B430.w2, B605.5.w5)

Sylvilagus spp. General Information:

  • "All cottontails have relatively large ears and feet." (B605.5.w5)

Newborn: --

Similar Species

--

Sexual Dimorphism

Specific Sylvilagus nuttallii Information

  • Females are usually approximately 4% larger than males. (B430.w2)

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References

Species Authors & Referees

Author: Kathryn Pintus BSc MSc MSc (V.w115)

ORGANISATIONS

ELECTRONIC LIBRARY
(Further Reading)
Click image for full contents list of ELECTRONIC LIBRARY

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Husbandry Information

Notes

  • --

Management Techniques

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Appearance / Morphology

Measurement & Weight

Notes

LENGTH
Adult:

Specific Sylvilagus nuttallii Information

  • Between 338-390 mm (Average: 362 mm). (B430.w2)
  • Females are usually approximately 4% larger than males. (B430.w2)
  • Tail length: 30-54 mm (Average: 48 mm). (B430.w2)

Newborns: --

HEIGHT
Adults and sub-adults: --
Juveniles: --

WEIGHT
Adult:

Specific Sylvilagus nuttallii Information

  • 628.5-871 g. (B430.w2)
  • 850 g. (B605.5.w5)

Newborns: --

GROWTH RATE --

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Head and Neck

Notes

GENERAL HEAD STRUCTURE:
Adult:

Specific Sylvilagus nuttallii Information 

  • The Mountain cottontail has relatively short ears which are rounded at the tip. (B430.w2, B605.5.w5)
  • The ears have hairy inner surfaces. (B430.w2)
  • "The whiskers are white or partly white, never black." (B430.w2)

Newborn: --

DENTITION:
Adult:

General Information

  • Rabbits and hares have a total of 28 teeth. (B285.w5a)
  • The lower tooth rows are closer together than the upper tooth rows. (B147)
  • Lagomorphs differ from rodents by having two pairs of upper incisors rather than just the one pair. The additional set of incisors are called peg teeth and are found directly behind the long pair in the upper jaw. (B147, B285.w5a, B605.1.w1)
  • At birth, lagomorphs actually have three pairs of upper incisors, but they quickly lose the outer incisor on each side. (B147)
  • The incisors are covered completely by enamel. (B147)
  • The upper incisors' roots are found in the skull's premaxillary bones. However, the length of the lower incisors' roots varies. (B147)
    • [Note: lagomorphs have teeth which grow throughout their lives. For this reason the portion of the teeth which is not exposed (not above the gum line) is strictly speaking not a "root"; however, it is sometimes convenient to describe it as a root.]
  • The first upper incisors have a straight cutting edge. (B147)
  • The peg teeth lack a cutting edge. (B147)

EYES:
Adult:

General Information

  • Lagomorph eyes are positioned such that they allow for good broad-field vision. (B285.w5a)
  • Hares and rabbits have large eyes which are adapted to both their crepuscular and nocturnal activity patterns. (B285.w5b)
  • Leporids have "large eyes to increase visual acuity in dim light." (B430.w2)

Newborn: --

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Legs, Spine and Tracks

Notes

Specific Sylvilagus nuttallii Information
  • Long hind legs. (B430.w2, B605.5.w5)
  • Long, dense hair covers the feet. (B430.w2, B605.5.w5)

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Tail

Notes

Specific Sylvilagus nuttallii Information
  • Large tail. (B430.w2, B605.5.w5)
  • Grizzled. The upperside is dark, and the underside is white. (B430.w2)

Sylvilagus spp. General Information:

  • 15 - 60 mm. (B147)
  • 2.5 - 6 cm. (B285.w5c)

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Skin / Coat / Pelage

Notes

Adult:

Specific Sylvilagus nuttallii Information

  • Dorsal surface is greyish, whilst the undersides are white. (B605.5.w5)
  • Tail is grizzled; the upperside is dark, and the underside is white.. (B430.w2, B605.5.w5)
  • "The whiskers are white or partly white, never black." (B430.w2)

Sylvilagus spp. General Information:

Adult Colour variations: --

Newborn / Juvenile: --

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Detailed Anatomy Notes
(Summary information provided for pertinent species-specific data cross-referenced in Wildpro)

Notes

Skull

Sylvilagus spp. General Information:

  • Species of this genus have an interparietal bone. (B605.5.w5)
  • The skull has a highly fenestrated maxillary bone. (B605.5.w5)
Female reproductive tract

Sylvilagus spp. General Information:

  • Females have four or five pairs of mammae. (B147, B287)
Male reproductive tract

Lagomorph general information

  • Male lagomorphs lack a baculum. (B147)
  • Testes of lagomorphs are in the scrotum located in front of the penis. (B147)

Sylvilagus spp. General Information:

  • Males have inguinal and coagulating glands. (B287)

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Life Stages / Natural Diet / Physiology

Life Stages

Notes

BREEDING SEASON:

Specific Sylvilagus nuttallii Information

  • "The onset and duration of the breeding season varies within the range of the species." (B605.5.w5)
  • Northeastern California: from April to July. (B605.5.w5)
  • Central Oregon: mid-February to the end of July. (B605.5.w5)
  • In Oregon, mating occurs between the end of February and early July. (B287)

OESTRUS / OVULATION:

Specific Sylvilagus nuttallii Information

GESTATION / PREGNANCY:

General Information

  • The gestation period for rabbits is usually between 27-30 days. (B285.w5b)
  • Under adverse conditions (such as during climatic or social stress), female lagomorphs are able to resorb embryos. (B285.w5a)
  • It is thought that some lagomorph species are able to conceive a second litter even before the last young is born; this is known as superfetation. (B285.w5a)

Specific Sylvilagus nuttallii Information

  • Gestation period is between 28 and 30 days. (B147, B287, B430.w2)
  • Pregnant females are found at different times of the year depending upon the region:
    • Oregon, USA: End of February to July.
    • Northeastern California, USA: April to July.
    • New Mexico, USA: August.

    (B287)

PARTURITION / BIRTH:

General Information

  • Newborn rabbits are born with very little or no fur, and their eyes do not open until 4-10 days after birth. (B285.w5b)
  • Rabbits produce altricial kittens (B285.w5b, B430.w2) which are born into fur-lined nests built either under dense cover or within underground chambers. (B285.w5b)

Specific Sylvilagus nuttallii Information

  • In British Columbia (Canada), females are known to give birth between April and July. (B287)

NEONATAL / DEVELOPMENT:

General Information

  • Young are only suckled briefly once every 24 hours. (B285.w5b)
  • Rabbit kittens remain together within their breeding chambers. (B285.w5)

Specific Sylvilagus nuttallii Information

  • "When the young reach a weight of about 75 grams (5 oz), they leave the nest for brief periods." (B430.w2)
  • Young are independent at approximately four to five weeks of age. (B287)

LITTER SIZE:

Specific Sylvilagus nuttallii Information

  • Litter sizes vary within the range of this species. (B605.5.w5)
  • Four to eight young per litter. (B430.w2)
  • Average litter size is between four and six young, with a range varying from one to as many as eight. (B605.5.w5)
  • Litter size varies between one and eight young, though five or six appears to be most common. (B287)

TIME BETWEEN LITTERS / LITTERS PER YEAR:

General Information

  • The inter-birth interval in lagomorphs is reduced by the phenomenon of induced ovulation, and post-partum oestrus, which allows females to conceive immediately after she has given birth. (B285.w5a)
  • A female can produce up to three or four litters per year. (B430.w2)

Specific Sylvilagus nuttallii Information

  • Up to five litters per year per female. (B430.w2)
  • Most females produce four litters per year. (B147)
  • California: two litters. (B605.5.w5)
  • Oregon: four or five litters. (B605.5.w5)
  • Between two and five litters per year per female. (B287)
  • A female will produce an average of 22 young per year. (B430.w2)
  • Oregon: a female can produce up to 22 young per year. (B605.5.w5)

LACTATION / MILK PRODUCTION:

  • Leporids only release milk once in every 24 hour period. (B285.w5b)
  • Leporid milk has a very high fat and protein content, and as such is highly nutritious. Although the lactation period is brief, the milk is pumped into the young at a high speed.(B285.w5b)
  • The lactation period has a duration of between 17 and 23 days. (B285.w5b)

SEXUAL MATURITY:

General Information

  • Most species of lagomorph reach sexual maturity relatively early. (B285.w5a)

Specific Sylvilagus nuttallii Information

  • Juvenile breeding is rare. (B605.5.w5)

MALE SEASONAL VARIATION:

Specific Sylvilagus nuttallii Information

  • In Oregon (USA), testes are large between January and July. (B287)

LONGEVITY / MORTALITY:

General Information

  • Rabbits and hares in the wild live for less than a year on average; a maximum age of 12 years has been recorded in a couple of species. (B285.w5b)

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Natural Diet

Notes

NATURAL DIET:

General Information

  • Lagomorphs only eat vegetation, mainly grasses and other herbaceous plants. Bark from young trees and small shrub stems may be eaten when food supplies are scarce. (B147, B285.w5c, B430.w2)

Sylvilagus spp. General Information:

  • Cottontails eat a wide variety of plants, the majority of which are herbaceous species. (B147, B285.w5c)
  • During the winter months in colder regions, cottontails feed on the bark and twigs of woody vegetation. (B147, B285.w5c)

Specific Sylvilagus nuttallii Information

  • The following are important in the Mountain cottontail's diet:

    • Sagebrush

    • Western juniper

    • Various grasses

  • Grass is preferred during the spring and summer. (B430.w2, B605.5.w5)

  • Primarily feed on sagebrush. (B605.5.w5)

QUANTITY EATEN: --

STUDY METHODS: --

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Hibernation / Aestivation

Notes

General Information
  • Active year-round. (B147)

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Haematology / Biochemistry

Notes

HAEMATOLOGY: --

BIOCHEMISTRY: --

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Detailed Physiology Notes
(Summary information provided for pertinent species-specific data cross-referenced in WILDPro)

Notes

Note: There is very little data specific to this species so the details below are from general lagomorph, leporid and cottontail information.

METABOLISM (TEMPERATURE): --

RESPIRATORY SYSTEM (RESPIRATION): --

CIRCULATORY SYSTEM (PULSE/HEART RATE): --

GASTROINTESTINAL SYSTEM (FAECES AND GUT MOTILITY):

General Information

  • Lagomorphs have digestive systems which are adapted for processing large quantities of vegetation. (B285.w5a)
  • Lagomorphs are well adapted for obtaining the greatest possible value from their food. They produce two types of fecal material: moist pellets and dry pellets. The moist pellets are expelled and then eaten (a behaviour known as coprophagy (B285.w5a)); this is done with little or no chewing, and as a result the majority of the food passes through the digestive tract twice (this is thought to have the same function as 'chewing the cud' in ruminants). The dry faecal pellets are not eaten. (B147)

URINARY SYSTEM (URINE): --

CHROMOSOMES: --

MUSCULO-SKELETAL SYSTEM: --

SPECIAL SENSES AND VOCALISATIONS:

General Information

  • All lagomorphs use scent products secreted from special glands. (B285.w5a) These glands are located under the chins and in the groin, and are believed to play a key role in sexual communication, as well as in signalling social status in some gregarious species. (B285.w5b)
  • Whereas pikas tend to be more vocal, rabbits and hares rely strongly on scent rather than sound as a means of communication. (B285.w5b)
  • High-pitched distress squeals are emitted by leporids when captured by a predator, and specific alarm calls are produced in five rabbit species. (B285.w5b, B430.w2)
  • Some rabbit species thump the ground with their hind feet when faced with danger (B285.w5b, B430.w2); this reaction is thought to be a warning to nestlings underground. (B285.w5b)
  • The conspicuous white underside present on the tails of some rabbit species can act as a visual warning to other individuals when fleeing from a predator. These species tend to be found in more open habitats. (B285.w5b)

Sylvilagus spp. General Information

  • Rarely vocalise. (B285.w5c)
  • "Several species utter squeals and high-pitched calls of distress." (B147)

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Behaviour

Feeding Behaviour

Notes

General Information
  • Lagomorphs are well adapted for obtaining the greatest possible value from their food. They produce two types of fecal material: moist pellets and dry pellets. The moist pellets are expelled and then eaten; this is done with little or no chewing, and as a result the majority of the food passes through the digestive tract twice (this is thought toe have the same function as 'chewing the cud' in ruminants). The dry faecal pellets are not eaten. (B147)

Specific Sylvilagus nuttallii Information

  • Most feeding occurs at dawn and dusk. (B430.w2)
  • Feeding usually occurs in clearings near to cover, or in the shelter of brush. (B430.w2, B605.5.w5)
  • Known to frequently climb into juniper trees to feed. (B147)

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Parental Behaviour

Notes

Note: There is very little data specific to this species so the details below are from general leporid and cottontail information.

General Information

  • Male leporids are not generally involved in care of the young. However, if adult females attack young leporids, males will intervene, a behaviour known as 'policing'. (B285.w5b)
  • Even maternal care of the young is not particularly prominent in leporids, hence this reproductive strategy is known as 'absentee parentism'. (B285.w5a)
  • Leporids demonstrate an unusual system of nursing; the young are suckled only briefly (often less than five minutes) just once every 24 hours. (B285.w5b)
  • It is thought that the lack of social contact between the mother and her young is a strategy which diminishes the chances of attracting the attention of predators. (B285.w5b)
  • The entrances to breeding tunnels are carefully re-sealed following each bout of suckling (B285.w5b)

Sylvilagus spp. General Information:

  • The females of most species of Sylvilagus dig nest holes, about 100-150 mm deep and 120 mm wide; sometimes slanted, and both lined and covered with soft plant fibres and the female's own fur, which she plucks from her underside.  (B147)
  • The female does not herself live in the nest. To feed the young she crouches over the nest, the kits climbing to the top of the nest to nurse. (B147)

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Social Behaviour / Territoriality / Predation / Learning

Notes

SOCIAL BEHAVIOUR:

General Information

  • Most North American leporid species are solitary, but congregations of these animals often occur in favoured feeding grounds. (B430.w2)
  • Rabbits are solitary to gregarious. (B430.w2)

Sylvilagus spp. General Information:

  • Most species within this genus are solitary. (B147)
  • May chase off other individuals if they approach too closely. (B147)
  • "Not colonial, but some species form social hierarchies in breeding groups." (B285.w5c)
  • "Cottontail behavior is stereotyped and fairly consistent with other rabbit species." (B605.5.w5)

Specific Sylvilagus nuttallii Information

  • This species is generally solitary. (B430.w2, B605.5.w5)
  • Individuals will concentrate in areas of suitable habitat. (B430.w2)
PREDATION: 
Predator Avoidance
  • Rabbits use dense cover to hide from predators. (B285.w5b)

Sylvilagus spp. General Information:

  • When under threat from a predator, cottontails sit completely still and remain quiet, even when closely approached. They are capable of staying like this for 15 minutes if necessary. (B147)

Specific Sylvilagus nuttallii Information

  • "When disturbed the rabbit will usually run 5-15m into cover, then pause, with ears held erect." (B605.5.w5)
POPULATION DENSITIES

Sylvilagus spp. General Information:

  • "Population levels vary markedly between species and from year to year, depending on climate, habitat type and other factors." (B605.5.w5)
  • Cottontails tend to be cyclic in abundance. (B605.5.w5)
  • "Habitat is the key to cottontail abundance." (B605.5.w5)
    • Desert species: normal densities are thought to be less than one rabbit per hectare. (B605.5.w5)

Specific Sylvilagus nuttallii Information

  • Population densities for this species vary. (B605.5.w5)
  • In shrub-juniper scrublands in central Oregon, densities vary between 0.06-2.5 individuals per hectare. (B605.5.w5)
HOME RANGES AND DISTANCES TRAVELLED

Sylvilagus spp. General Information:

  • The home ranges of females are generally smaller than those of males. (B147)
  • These species have stable home ranges of a few hectares which overlap. (B285.w5c)
TERRITORIALITY

General Information

  • Ranges of individuals may overlap in favoured feeding grounds. (B285.w5b)

Sylvilagus spp. General Information:

  • Not territorial. (B285.w5c)

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Sexual Behaviour

Notes

Note: There is very little data specific to this species so the details below are from general lagomorph and cottontail information.

  • All lagomorphs use scent products secreted from special glands. (B285.w5a) These glands are located under the chins and in the groin, and are believed to play a key role in sexual communication, as well as in signalling social status in some gregarious species. (B285.w5b)

Sylvilagus spp. General Information:

  • "Several males may come together during the breeding season and pursue an estrous female." (B147)

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Activity Patterns, Self-grooming and Navigation

Notes

Note: There is very little data specific to this species so the details below are from general leporid and cottontail information.

ACTIVITY PATTERNS:

Sylvilagus spp. General Information:

  • Active year-round. (B147)
  • The majority of species move by characteristic bunny hopping. (B147)
  • It is thought that all species are capable of swimming. (B147)
SELF-GROOMING: --
CIRCADIAN RHYTHM:

Sylvilagus spp. General Information:

  • Mostly nocturnal or crepuscular. (B147)
  • Cottontails are sometimes seen during daylight hours. (B147)
  • Active at night or during the day. (B285.w5c)
SPEED OF MOVEMENT:

General Information

  • The North American leporids are able to escape predators by taking instant flight at high speed. (B430.w2)
NAVIGATION: --

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Habitat and Range

General Habitat Type

Notes

Specific Sylvilagus nuttallii Information
  • Scrub and forest. (B51)
  • Primarily sagebrush habitat. (B430.w2, B605.5.w5)
  • In the north, it is generally associated with sagebrush Artemisa species. (B605.5.w5)
  • In the southern parts of its range, it may be found in timbered areas. (B430.w2, B605.5.w5)
  • Tends to prefer dry brushy or rocky areas. (B147, B605.5.w5)
  • Commonly associated with wooded areas. (B605.5.w5)
  • "This species inhabits wooded of brushy areas, commonly near rocky ravines." (B430.w2)
  • This species favours riparian zones with abundant willows. (B430.w2)
  • In areas where its range overlaps that of the Sylvilagus audubonii - Desert cottontail, the Mountain cottontail tends to favour higher, rocky sagebrush areas. (B430.w2)
  • Found at elevations between 1,500 m and more than 3,450 m. (B605.5.w5)
  • Habitat varies across the range of this species. (B605.5.w5)

Sylvilagus spp. General Information:

  • The presence of escape cover is an essential habitat requirement for these species. (B605.5.w5)

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Nests / Burrows / Shelters

Notes

Sylvilagus spp. General Information:

  • Cottontails are not thought to dig burrows. (B147)
  • Some species are known to make use of burrows made by other animals. (B147)
  • Also take shelter in brush piles and forms. (B147)
  • Several forms may be connected by flattened trails made through regular use of pathways. (B147)
  • "All species occupy burrows made by other animals or inhabit available shelter or hide in vegetation." (B285.w5c)
  • The females of most species of Sylvilagus dig nest holes, about 100 - 150 mm deep and 120 mm wide; sometimes slanted, and both lined and covered with soft plant fibres and the female's own fur, which she plucks from her underside.  (B147)
  • The female does not herself live in the nest. To feed the young she crouches over the nest, the kits climbing to the top of the nest to nurse. (B147)
Specific Sylvilagus nuttallii Information
  • "The mountain cottontail lives in burrows and rock crevices where vegetation is sparse, and in "forms" (above-ground nests) where cover is dense." (B430.w2)
  • Females build nests, which are cup-like and lined with dried grass and fur. (B430.w2)
  • This species has been considered by some to be semi-arboreal, due to its habit of climbing into juniper trees to feed. (B147)
  • Uses both burrows and forms. (B605.5.w5)
  • The Mountain cottontail does not dig its own burrows. (B605.5.w5)

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Distribution and Movement (Migration etc.)

Notes

Specific Sylvilagus nuttallii Information
  • Western USA. (B51)
  • This species is found in the intermountain area of North America. (B285.w5c, B605.5.w5, B607.w20)
  • Its range extends from southern British Columbia to southern Saskatchewan, south to east California, northwestern Nevada, central Arizona and northwestern New Mexico. (B285.w5c, B607.w20)
  • The Mountain cottontail is found in southwestern Canada. Also found in western conterminous USA. (B147)
  • "The mountain cottontail is found in the intermountain West from just above the Canadian border south to Arizona and New Mexico, and from the eastern slopes of the Rocky Mountains west to the Cascade-Sierra crest." (B430.w2)
  • Sylvilagus nuttallii grangeri  - "...southern Alberta and Saskatchewan north to Calgary and Saskatoon, and south through Montana, Wyoming, southern Idaho, central Nevada, most of Utah, north-central Arizona, and the northwestern corner of Colorado." (B430.w2)
  • Sylvilagus nuttallii nuttallii - "...eastern Washington, extreme south-central British Columbia, northwestern Idaho, eastern Oregon, northeastern California, and northwestern Nevada." (B430.w2)
  • Sylvilagus nuttallii pinetis  - "...north-central Colorado, south and west to southeastern Utah and northeastern Arizona, and south to northern New Mexico." (B430.w2)
  • In California, these species is found at elevations from 1,500m to more than 3,450 m. (B605.5.w5)

Geographic Sympatry

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Conservation

Species variation

Notes

Specific Sylvilagus nuttallii Information
Currently recognised subspecies include:
  • Sylvilagus nuttalli nuttalli (B430.w2, B605.5.w5) including Sylvilagus nuttallii artemesia. (B607.w20)
  • Sylvilagus nuttalli grangeri: (B430.w2, B605.5.w5) including Sylvilagus nuttallii perplicatus. (B607.w20)
  • Sylvilagus nuttalli pinetis. (B430.w2, B605.5.w5, B607.w20)

NB: names in non-bold font are reported as synonyms for that particular subspecies from the reference B607.w20.

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Conservation Status

Notes

WILD POPULATION - IMPORTANCE:

Specific Sylvilagus nuttallii Information

  • Common. Population declines appear to be occurring in southwestern North Dakota. (B430.w2)

GENERAL LEGISLATION: --

CITES LISTING: --

RED-DATA LIST STATUS:

Specific Sylvilagus nuttallii Information

  • IUCN - Lower Risk (least concern). (W2.Apr08.w85)

THREATS: --

PEST STATUS / PEST POPULATIONS: --

CAPTIVE POPULATIONS: --

TRADE AND USE:

Specific Sylvilagus nuttallii Information

  • This species is "...a common game species throughout the intermountain west of the United States." (B605.5.w5)
  • State and provincial wildlife agencies manage the species by establishing hunting seasons and bag limits. (B605.5.w5)

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