Sacramento Fish & Wildlife Office
Species Account
RIPARIAN BRUSH RABBIT
(Sylvilagus bachmani riparius)
There is a special riparian brush rabbit species account for 4th, 5th and 6th grade students.
CLASSIFICATION: Federal Endangered Species (Federal Register 65:8881 (pdf); February 23, 2000)
CRITICAL HABITAT: Determined to be prudent. Will be designated when funding allows.
RECOVERY PLAN: Recovery plan for the upland species of the San Joaquin Valley, California, September 30. 1998. (pdf format)
In a partnership with the Bob Gallo family, the U.S. Fish and Wildlife Service
and the Endangered Species Recovery Program/CSU-Stanislaus are releasing more
than two dozen members of a new generation of captive-bred riparian brush rabbits
into the wild.
The new releases, taking place on privately owned ranch land that is adjacent to the San Joaquin River National Wildlife Refuge west of Modesto, marks the beginning of an effort to establish a second self-sustaining population of the endangered rabbits in their native habitat along rivers in the San Joaquin Valley. News Release
Visit our riparian brush rabbit recovery page
DESCRIPTION:
The riparian brush rabbit (Sylvilagus bachmani riparius) is a medium to small cottontail in the Leporidae family. Its colors vary from dark brown to gray above to white underneath. Adult rabbits are about 11 to 14 inches long, weighing less than 2 pounds.
There are 13 subspecies of brush rabbit, distributed from the Columbia River to the tip of Baja California. The riparian subspecies can be distinguished by its relatively pale color, gray sides and darker back. When viewed from above, its cheeks protrude outward rather than being straight or concave, as in the other subspecies. Brush rabbits can be distinguished from desert cottontails by their smaller, inconspicuous tail and uniformly colored ears (i.e., no black tips).
Habitat for the riparian brush rabbit consists of riparian communities dominated by willow thickets (Salix spp.), California wild rose (Rosa californica), Pacific blackberry (Rubus vitifolius), wild grape (Vitis californica), Douglas' coyote bush (Baccharis douglasii) and various grasses.
Brush rabbits have small home ranges that usually conform to the size of available brushy habitat. Avoiding large openings in shrub cover, they frequent small clearings, where they feed on a variety of herbaceous vegetation, including grasses, sedges, clover, forbs, shoots and leaves. Grasses and other herbs are their most important food. Green clover (Trifolium wormskioldii) is their favorite.
Riparian brush rabbits breed from around January to May, putting them at a disadvantage to desert cottontails, which breed year round. Litters average three or four young, with each female having three or four litters per year.
Find lots more information in the Draft Habitat Assessment Guidelines & Survey Protocol for the Riparian Brush Rabbit and the Riparian Woodrat (PDF).
DISTRIBUTION:
Because the subspecies was not described until after it is believed to have been extirpated from most of its historic range, definitive information on its former distribution is lacking. Today, the only known native populations are at Caswell Memorial State Park on the Stanislaus River and along an overflow channel of the San Joaquin River.
THREATS:
Potential threats to this species include habitat conversion to agriculture, wildfire, disease, predation, flooding, clearing of riparian vegetation, and the use of rodenticides.
There has been a statewide reduction of riparian communities by nearly 90 percent due to elimination and modification of riparian forests along valley floor river systems to urban, commercial, and agricultural development, wood cutting, reclamation and flood control activities, heavy groundwater pumping, river channelization, dam building, and water diversion. The species is at risk from the lack of elevated mounds with protective cover to serve as flood refuges within remaining riparian habitat.
REFERENCES FOR ADDITIONAL INFORMATION:
Basey, G.E. 1990. Distribution, ecology, and population status of the riparian brush rabbit (Sylvilagus bachmani riparius). Turlock, CA: California State Univ., Stanislaus. M.S. thesis.
Sandoval, T.M., D.F. Williams, and G.W. Colliver Endangered Species Recovery Program. Species account
U.S. Fish and Wildlife Service. 1998. Recovery plan for the upland species of the San Joaquin Valley, California, September 30. 1998. (pdf format) Portland, OR.
U.S. Fish and Wildlife Service. 2000. Endangered and Threatened Wildlife and Plants; Final Rule to List the Riparian Brush Rabbit and the Riparian, or San Joaquin Valley, Woodrat as Endangered. Portland, Oregon. (pdf)
Photo credit: FWS photo
