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Vanished Rabbit Reappears on Central California's Dos Rios Ranch

Posted by Dave Sanden, Natural Resources Conservation Service, California in Conservation
Feb 21, 2017
The riparian brush rabbit is state and federally endangered, with all known populations in the northern San Joaquin Valley facing significant threat of extinction. Declines of brush rabbits have largely been attributed to loss of habitat. Photo courtesy USFWS Pacific Southwest Region.
The riparian brush rabbit is state and federally endangered, with all known populations in the northern San Joaquin Valley facing significant threat of extinction. Declines of brush rabbits have largely been attributed to loss of habitat. Photo courtesy USFWS Pacific Southwest Region.

Some exciting news recently came from a large wetlands restoration project now underway in Central California. River Partners, a nonprofit conservation organization, documented the first occurrence of a state and federally endangered rabbit on its habitat preserve at Dos Rios Ranch, a key piece of riverfront habitat located at the confluence of the Tuolumne and San Joaquin rivers in Stanislaus County.

Thanks to a generous loan of wildlife cameras from a professor at the University of California, Davis, River Partners’ summer interns captured images of riparian brush rabbits at Dos Rios Ranch in July in remnant riparian habitat along the Tuolumne River. Riparian brush rabbits are a critically endangered subspecies of rabbit that was thought to be extinct following catastrophic flooding in 1997.

“This rabbit was photographed over a mile away and across the river from known populations,” said Julie Rentner of River Partners. “The nearby San Joaquin River National Wildlife Refuge hosts a thriving population of reintroduced riparian brush rabbits, but there has been no proof that the rabbits were at Dos Rios Ranch since 1997. The camera is still set up and is capturing additional images, so we’ll certainly turn up more if there are more rabbits out there.”

The multi-million dollar wetlands restoration efforts on Dos Rios Ranch began in 2012. The land was enrolled in the former Wetlands Reserve Program, or WRP, a conservation easement program offered by USDA’s Natural Resources Conservation Service, (NRCS). Easement programs offer landowners the means to restore, enhance and protect wetlands on their property through easements. The 2014 Farm Bill merged WRP with other easement programs to form a new one: the Agricultural Conservation Easements Program, (ACEP), which continues to further wetlands restoration.

The project’s main objectives include restoring the riparian corridor, providing a critical link between this easement and other USDA easements, establishing self-sustaining native plant communities, and providing riparian habitat for wildlife. The property had been used for agricultural production for over a century. This project transforms it back into its former glory as a wetland. NRCS is working with the landowner, River Partners, to design and implement the project and is actively managing and monitoring the restoration process.

The 1,150-acre project area contains remnant floodplain habitats that include wetlands, riparian woodlands and agricultural lands. The 1,600-acre Dos Rios Ranch property was purchased by River Partners in 2012 with funding from seven local, state and federal funding partners for use as a flood management and wildlife habitat project.

“Restoration work is progressing using a phased approach,” said NRCS wildlife biologist Karl Kraft.

Currently, about 500 acres are being restored. Work on 137 acres began in spring 2013. The second phase began in fall 2013 on 384 more acres, and the third phase will begin in 2015, Kraft said.

“More than 944 acres will be retired from production and restored to riparian habitat when the work is complete,” he said. “Numerous wildlife species should benefit from the restoration, including the federally endangered riparian brush rabbit, riparian woodrat, least bell’s vireo, and threatened valley elderberry longhorn beetle,” Kraft said.

Trees, such as black willow, and other native woody species are being planted in rows, much like an orchard, with planting berms and space between the rows for native grasses and forbs. Furrow irrigation between the planted rows is used to apply water to plantings in the initial growing seasons.

Rabbit foraging areas of low herbaceous plants such as Spanish clover, gumplant and native grasses have been established adjacent to patches of clover near the tree plantings. Dense thickets of California wildrose and blackberry established away from trees will offer protection against hawks and other predators.

Some areas of dense, low growing vegetation have been established on elevated ground, known as “bunny mounds,” to provide rabbits cover and flood protection. Kraft said that five of these bunny mounds have been constructed so far.

“The riparian brush rabbit was a primary reason for protecting and restoring the ranch,” said Dean Kwasny, easement programs specialist with NRCS. “It’s encouraging to see that our conservation efforts are having tangible benefits for this focal species.”

Category/Topic: Conservation

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Dec 02, 2014

It would be interesting to know the myxomatosis status of these colonies...if for no other reason than to monitor it and make domestic rabbit raisers aware of its presence in an area, so they can take preventive measures.

Karl Kraft
Dec 03, 2014

The California State University Stanislaus Endangered Species Recovery Program (ESRP) monitors the Riparian Brush Rabbit population on the Refuge. Conversation this morning with a local biologist (Jeff Holt) who worked for ESRP informed me “in the beginning captured rabbits would have blood samples drawn to check for pathogens, but this was changed to just a health screen and then drawing blood if the animal had signs of health issues. Only healthy animals were released and I also can’t remember catching sick animals during subsequent trappings for collared rabbits.”

Dec 11, 2014

I'm curious about the decision to plant the trees in rows like an orchard. What ecological benefit was the driver there?

Thanks! Keep up the great work!

Ben Weaver
Dec 11, 2014

@Mason - thanks for asking. Competition from weeds and moisture stress is the leading cause of plant failure in riparian restoration projects. Planting rows are used to facilitate furrow irrigation and to manage weeds with disking and strip-spraying. Planting rows are pulled in a curved fashion as not to appear straight to the human eye. Willows, elderberry, rose, blackberry and others grow very rapidly, and by the end of the third growing season, the appearance of the planting row is barely noticeable.