Flood survivors make a comeback

"After a dramatic decline of the riparian brush rabbit in the late 1990s, the state and federally listed rabbit has recovered to the point where it’s realistic to consider downlisting the species from endangered to threatened, and eventually delisting it entirely", said Kim Forrest, refuge manager for the San Luis National Wildlife Refuge Complex, which includes the San Joaquin River National Wildlife Refuge. The refuge is the site of a propagation and reintroduction project for North America’s most endangered lagomorph. Credit: Brian Hansen/USFWS

Tiny riparian brush rabbits rescued during the winter 2016-17 floods are being saved from extinction by state and federal habitat restoration efforts

By Steve Martarano
January 30, 2018

Wielding a hiking stick because of an old injury, Dr. Patrick Kelly, head of the Endangered Species Recovery Program at Stanislaus State University, wades through a tall mass of brush and weedy vegetation on Christman Island, part of the San Joaquin River National Wildlife Refuge about 15 miles west of Modesto, California.

Dr. Patrick Kelly (left) and student assistant Antonio Garcia checking on cameras meant to monitor riparian brush rabbits at  San Joaquin River National Wildlife Refuge. Credit: Steve Martarano/USFWS

He and student assistant Antonio Garcia, on this clear early January day, are headed to two infrared trail cameras that were deployed the previous week to monitor the endangered riparian brush rabbit, a species Kelly knows well. He’s been studying the elusive small critters since the early part of the century.

“This is why they call it ‘riparian’ brush rabbit,” said Kelly, a recipient of the U.S. Fish and Wildlife Service’s Recovery Champion Award in 2008. “The thick riparian habitat helps them hide from their many predators.”

The camera stations, 54 in total, are used to help determine how well the rabbits recovered from the devastating 2016-17 floods. They are just one of the many tools that the U.S. Fish and Wildlife Service and a host of state, federal and private entities such as River Partners have utilized since the early 2000s to help save the iconic rabbit at the refuge from extinction. This resulted in the protection and restoration of approximately 5,000 acres of potential habitat.

Biologists check on a remote game camera used to monitor riparian brush rabbits who may have survived last winter’s devastating floods at the refuge. Credit: Steve Martarano/USFWS

Until 1998, the only known population of riparian brush rabbits was at the small 250-acre Caswell Memorial State Park, located northeast of the refuge along the Stanislaus River. The confirmation of a second population in the South Delta initiated a controlled propagation program in 2001 and the refuge became the center of the recovery effort with the first releases of captive-bred rabbits in summer 2002.

Although the refuge was created in 1987 to provide winter forage and roosting habitat for the then-threatened Aleutian Canada goose and other wildlife and native plants, it took on new importance in 2002 as the epicenter of the rabbit’s recovery.

Now, after that dramatic decline of the subspecies into the late 1990s, this state and federally listed rabbit has recovered to the point where it’s realistic to consider downlisting the species from endangered to threatened, and eventually delisting it entirely," said Kim Forrest, refuge manager for the San Luis National Wildlife Refuge Complex (which includes the San Joaquin National Wildlife Refuge).

“This is truly an endangered species success story; the riparian brush rabbit recovery work has been one of our refuge’s greatest accomplishments,” said Forrest, who was recognized in July 2016 for her longtime efforts with the rabbit at the 5th World Lagomorph Conference hosted by Stanislaus State University.

Scores of traumatized riparian brush rabbits were flushed out of their habitat during the winter storms of 2016-17 which left them stranded on small areas of high ground. Credit: Rick Kimble/USFS

Lagomorphs include all hares (jackrabbit, rabbits, and pikas) and totals less than 100 species worldwide. Yet three of the species – riparian brush rabbit, desert cottontail, and black-tailed jackrabbit – are all found together on the San Joaquin River National Wildlife Refuge, which Kelly calls “highly unusual.”

“Due to a very large, collaborative, strong, and synergistic partnership, the rabbit is rapidly moving from being perhaps the most endangered mammal in California and in the U.S. – to potentially being removed from the list of endangered species,” Forrest added.

A riparian brush rabbit caught on a remote infrared camera in a photo from the refuge in late December 2017. Credit: CSU Stanislaus

The secretive and shy one and half pound mammal was once abundant along rivers in the south Delta and parts of Stanislaus County until decades of extensive habitat loss coupled with widespread flooding impacted the rabbit until just an estimated few hundred remained in existence by the 1990s. As a result, it was federally listed as endangered in 2000 and by the state in 2008 due to severe population declines.

Riparian brush rabbits rescued during the floods of winter 2016-17, huddle together while being transported to higher ground. Credit: Eric Hopson/USFWS

Recovery efforts for the rabbit began in earnest with the captive breeding and reintroduction program on the refuge and adjacent private lands. Captive-bred rabbits were radio-collared and tagged, so that they could be monitored by biologists.

The resulting development and management of the $2 million program helped establish a new population of the rabbits. Three large propagation pens of various sizes funded by the Central Valley Project Improvement Act, Habitat Restoration Program and the Central Valley Project Conservation Program were built on state property.

Researchers released and distributed rabbits in a wide variety of habitat locations, and a total of 1,500 captive-bred riparian brush rabbits were released. Captive propagation ended in 2013.

Now, the rabbits occupy newly restored habitat in a block that is 10 times larger than the habitat of its known population prior to recovery efforts. And the area where the Service can purchase land for the refuge has been expanded to a narrow riparian corridor - 35 river miles to the south.

Managers all agree the program is at a key point with how to proceed with recovery efforts to downlist, and ultimately delist, the species.

“Restored populations have survived fires and floods, and their range is expanding,” said refuge manager Eric Hopson. “However, getting to the finish line with this program means the species is delisted. That will likely require additional funding for refuge land acquisition and habitat restoration, and better information on the current population status.”

“Restored populations have survived fires and floods, and their range is expanding,” said San Joaquin River refuge manager Eric Hopson. “However, getting to the finish line with this program means the species is delisted.”  Credit: Steve Martarano/USFWS

Kelly’s camera monitoring program is in an area flooded by last winter’s storms, which left many rabbits without habitat and imperiled due to the rising flood waters. In February 2017, when those surviving rabbits headed to higher ground to escape the rising waters, they became easy prey to their many predators, including hawks, owls, dogs, foxes, coyotes, cats, raccoons and snakes.

Kelly, Hopson, and other biologists spent several weeks individually rescuing about 150 of the traumatized rabbits. These individuals were released in nearby areas of the refuge within habitat, safe from flooding.

No one is sure how many of those rescued rabbits survived – they live only a couple of years at most, but Kelly’s cameras will provide some information on how many are in the area.

In front of each camera, a dish of food was placed comprised of corn, oats and barley flavored with molasses, and when an animal started feeding, the camera automatically took a series of photos.

At the two remote trail camera sites monitored that recent January day, all of the week-old food had been eaten, though apparently not by a riparian brush rabbit, which was expected at this time of the year.

Kim Forrest, San Luis National Wildlife Complex refuge manager shown with a riparian brush rabbit. She was recognized in 2016 for her longtime efforts with the rabbit at the 5th World Lagomorph Conference hosted by UC Stanislaus. Credit: USFWS

“This is a good sign, though,” Kelly said. “Last April, we would have been up to our waist in water here.

“By the very nature of the habitat they occupy and their secretive habits, brush rabbits are hard to survey for and even harder to census with a high degree of confidence,” Kelly said. “We now know that we can get a great deal of information on the rabbit’s distribution, abundance, and even behavior through the deployment of remotely-operated cameras.”

Kelly noted the study is recording the rabbit on all the riparian transects that have been camera-trapped so far, suggesting the population is rebounding from last winter’s flooding.

“The riparian transects are in the best habitat for the rabbit,” he said, “but about two-thirds of the transects are in transitional or grassland habitat, and so far we have not documented a rabbit on those. That is not surprising at this time of year, though. In the spring and summer when the habitat has greened up considerably, those transects may well harbor the brush rabbit.”

“That’s something we would not have been able to do without the habitat restoration and other conservation measures that were put in place following that first serious flood (in 2006),” Kelly added.

Moving forward, because flood escape habitat is critical for the survival of the species, efforts are focused on building high-water refuge spaces for the rabbit. It has become apparent that populations recover much quicker after flood events where high ground habitat is available.

“At this juncture, additional studies, a comprehensive status review of the program and an updated recovery plan are needed,” Hopson said. “That will help answer lingering questions such as where are the rabbits surviving and thriving, what is their optimal habitat, where should additional land be purchased and restored and if connectivity issues have been adequately addressed.”

Restored riparian brush rabbit habitat at the north end of the San Joaquin River National Wildlife Refuge. Credit: Steve Martarano/USFWS

Brush rabbits appear near sunset on San Joaquin River National Wildlife Refuge. The refuge is the site of a propagation and reintroduction project for North America’s most endangered lagomorph. Credit: Lee Eastman/USFWS

 

[Note: The Central Valley Project Conservation Program is managed by the Bureau of Reclamation, and the Central Valley Project Improvement Act, Habitat Restoration Program is jointly managed by the Service and Reclamation. These programs also funded riparian brush rabbit habitat restoration, surveys, and various aspects of the captive propagation activities.]

 

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Steve Martarano

About the writer...

Steve Martarano is currently a public affairs specialist in the San Francisco Bay-Delta Fish and Wildlife Office located in Sacramento, California.

He has spent almost 30 years in both state and federal government public affairs after a 10-year stint at a daily newspaper in Sacramento.

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