Brush Rabbit
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 Brush Rabbit (Finley National Wildlife Refuge)
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| Sylvilagus bachmani (Waterhouse, 1839) |
The Brush Rabbit (Sylvilagus bachmani), or Western Brush Rabbit, is a species of cottontail rabbit found in western coastal regions of North America, from the Columbia River in Oregon to the southern tip of the Baja California peninsula. Its range extends as far east as the eastern sides of the Sierra Nevada and Cascade mountain ranges.
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[edit] Habitat
Brush rabbits inhabit dense, brushy cover, most commonly in chaparral vegetation. They also occur in oak and conifer habitats and they will live in brush or grassland, and form networks of runways through the vegetation. Brush rabbits do not dig their own burrows or dens, but use the burrows of other species, brush piles, or forms. In the San Francisco Bay Area, it was found that brush rabbits concentrate their activities at the edge of brush and exhibit much less use of grassy areas. They do use the interior brush of the wilderness and it was also found that this may be a better environment for them than the chaparral one. Studies done on the brush rabbit in Oregon also showed that they rarely left the brushy areas they inhabit. Brush may be used more in the drier seasons while grasses are used in the wetter seasons in relation to growth of annual vegetation. Use of habitat also probably is related to the breeding season.
[edit] Physical description
The Brush Rabbit is smaller than many of the cottontails, and unlike most of them, the underside of its tail is grey rather than white (which may be why its common name does not include the word "cottontail"). The upperside of the brush rabbit's fur varies from light brown to grey in color, while the underside is usually always white. Adult rabbits measure anywhere from 10-14 inches long and rarely weigh over two pounds.
Large numbers of geographically defined subspecies have been proposed, including in Oregon, ubericolor; in California, cinerascens, mariposae, riparius, tehamae and trowbridgii; and in Baja California, cerrosensis, exiguus, howelli, peninsularis and rosaphagus. Subspecies bachmani, macrorhinus and virgulti are less geographically restricted. Sylvilagus bachmani riparius, the Riparian Brush Rabbit, is highly endangered; formerly numerous along the San Joaquin River and Stanislaus River, it is now reduced to a population of a few hundred in the Caswell Memorial State Park.
[edit] Reproduction
Mating in brush rabbits, as with other rabbits, may occur year-round but peak breeding seasons are between February and August. The gestation period of the brush rabbit female is about 22 days. A female brush rabbit can have as many as five litters per year but two to three is more common. One to seven young are born per litter and they are altricial. The average number born per litter is three.
[edit] Behavior
A trapping study of brush rabbits in the Berkeley Hills in northern California indicated that males had larger home ranges than females at all times of the year, and especially in May when females were moving the least. It is estimated the home ranges of the brush rabbit average just under one acre for males and just under half an acre for females. The shape of these home ranges are usually circular but depending on the vegetation can be different in size and shape. Range use probably is not circular in shape or uniform, but rather consists of a series of runways that directly connect high use areas within brush habitat. Intraspecific socio-spatial behavior appears to be variable and may reflect local resource conditions. Several rabbits have been observed to feed in the same area simultaneously, but maintained inter-individual distances of one to 24 feet before aggressive chases occurred. It has been shown that females tended to not overlap while males showed relatively extensive overlapping and this may indicate that females are territorial. Groups of brush rabbits may serve social purposes, such as predator detection, but this has not been proven.
[edit] Food
The brush rabbit feeds mainly on grasses and forbs, especially green clover, though it will also take berries and browse from bushes.
[edit] Predators and survival techniques
Its predators include cougars, coyotes, foxes, bobcats, weasels, and various raptors and snakes. Its survival strategies include remaining immobile, when in brushy areas, and zig-zag running when found and/or in open spaces.
[edit] Human interaction and impact
The brush rabbit is not hunted as are many other cottontail species, probably because of its small size. It is not a major cause of damage to crops or other human developments in its habitat. Certain subspecies of the brush rabbit are considered endangered and are protected by state and federal laws.
[edit] References
- Lagomorph Specialist Group (1996). Sylvilagus bachmani. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 09 May 2006. Database entry includes a brief justification of why this species is of least concern
- Sylvilagus bachmani (TSN 180123). Integrated Taxonomic Information System. Accessed on 23 March 2006.
