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Sylvilagus bachmanibrush rabbit

By Sara Crane and Rebecca Ann Csomos

Geographic Range

Sylvilagus bachmani ranges from the Columbia River in Oregon southward to the tip of Baja, California and from east of the Cascade and Sierra Nevada ranges and desert areas west throughout much of California (Wilson & Ruff 1999).

Habitat

As their name implies, brush rabbits are primarily found in areas with dense brushy cover. Brush rabbits rarely leave the brush for extended periods of time.

Physical Description

Brush rabbits are a small to medium sized cottontail. The pelage is evenly dark, consisting of steel gray, black, and orange. The ears are fairly small with a slight point. The tail is not prominent, on the top it is the same dark brown and white underneath.

Sylvilagus bachmani ranges in length from 11 inches to 14 1/2 inches. Females are generally a little bigger than males. The dental formula is 2/1, 3/2, 3/3, totalling 28. (Wilson & Ruff 1999, Verts & Carraway 1998).

  • Range mass
    0.48 to 0.92 kg
    1.06 to 2.03 lb
  • Average mass
    0.71 kg
    1.56 lb

Reproduction

Brush rabbits usually have three litters a year; although four litters are possible. Brush rabbits are not as fecund as other members of the genus. Breeding season for brush rabbits begins in December and lasts until May or June for rabbits in California. Brush rabbits in Oregon breed from February to August. Many breed again soon after giving birth.

The gestation period is about 27 days, with litters sizes of usually 2 to 4 young. The young are born altricial and stay in a lined and covered nest in the ground for about 14 days, opening their eyes on approximately the 10th day. The mother has 4 pairs of mammae and comes to feed her young at night. Maturity is reached at about 4 or 5 months after birth. Young brush rabbits are able to breed the following breeding season. (Chapman 1974, Wilson & Ruff 1999, Verts & Carraway 1998).

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Range number of offspring
    2 to 6
  • Average number of offspring
    3.5
  • Average number of offspring
    3.6
    AnAge
  • Average gestation period
    27 days
  • Average gestation period
    27 days
    AnAge
  • Range weaning age
    14 to 21 days
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    154 days
    AnAge

Behavior

Brush rabbits are active all year round and are mainly crepuscular. They come out of their brush area after sunset and remain active until very early morning. They may emerge again a few hours later, until late morning. They rarely emerge in the afternoon, most of that time is spent resting. However, on a nice day, brush rabbits may be observed basking in the sun.

Brush rabbits are wary and secretive animals. They use runways, tunnels, and burrows--although not as extensively as other members of their genus. When pursued, brush rabbits climb trees and scrubs. When brush rabbits are frightened their characteristic response is foot thumping. Thumps may continue for several minutes. Squeals and cries are vocalizations used by brush rabbits in pain or when scared.

To protect themselves from predators, brush rabbits can sit perfectly still for long periods of time. When threatened they run in a zig-zag manner at about 20 to 25 miles an hour.

Although a gregarious species while foraging, brush rabbits are mostly solitary. Brush rabbits inhabit individual home ranges, with male home ranges on average larger than female home ranges (Chapman 1974, Wilson & Ruff 1999, Verts & Carraway 1998).

Communication and Perception

Food Habits

Brush rabbits are herbivores whose diet varies with the season. Grasses make up a large portion of their diet. However, brush rabbits feed on other species of plants, including leaves, forbs and scrubs such as wild rose and blackberries. Whenever available, green clover is preferred (Chapman 1974, Wilson & Ruff 1999).

Economic Importance for Humans: Positive

Like many other rabbits, brush rabbits are hunted for sport and food. Some may be captured and raised for pets.

  • Positive Impacts
  • food
  • body parts are source of valuable material

Economic Importance for Humans: Negative

Brush rabbits are sometimes considered a pest because they can cause damage to crops and decorative vegetation. Brush rabbits have also been blamed for depredations on the seedlings planted for forest regeneration, however this is questionable (Verts & Carraway 1998).

Conservation Status

One subspecies of riparian brush rabbits, S. bachmani riparius, are considered endangered throughout their range under the U.S. Endangered Species Act. This subspecies occurs in the San Joaquin Valley of California and is also considered endangered by the state of California. Population declines are due to many factors, such as loss of natural habitat, wildfire, and disease.

Other Comments

Within the species Sylvilagus bachmani, there are 13 known subspecies.

Contributors

Sara Crane (author), University of Michigan-Ann Arbor, Rebecca Ann Csomos (author), University of Michigan-Ann Arbor, Cynthia Sims Parr (editor), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

altricial

young are born in a relatively underdeveloped state; they are unable to feed or care for themselves or locomote independently for a period of time after birth/hatching. In birds, naked and helpless after hatching.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chaparral

Found in coastal areas between 30 and 40 degrees latitude, in areas with a Mediterranean climate. Vegetation is dominated by stands of dense, spiny shrubs with tough (hard or waxy) evergreen leaves. May be maintained by periodic fire. In South America it includes the scrub ecotone between forest and paramo.

chemical

uses smells or other chemicals to communicate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

forest

forest biomes are dominated by trees, otherwise forest biomes can vary widely in amount of precipitation and seasonality.

herbivore

An animal that eats mainly plants or parts of plants.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

social

associates with others of its species; forms social groups.

tactile

uses touch to communicate

References

Chapman, J. 2 May 1974. Mammalian Species. The American Society of Mammalogists.

Colliver, G., T. Sandoval, D. Williams. 30 January 1997. Accessed December 6, 1999 at http://arnica.csustan.edu/esrpp/rbr.html.

Farrand, J. 1988. The Audubon Society Pocket Guide to Familiar Mammals of North America. New York: Alfred A. Knopf, Inc..

Nowak, R. 1999. Walker's Mammals of the World Volume II.. Baltimore: Johns Hopkins University Press.

Verts, B., L. Carraway. 1998. Land Mammals of Oregon. Berkeley: University of California Press.

Wilson, D., S. Ruff. 1999. The Smithsonian Book of North American Mammals. Washington: Smithsonian Institution Press.

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