Recent accomplishments of CDFW's scientific community
Camouflaged trap used to capture foxes for the study. CDFW photo by Jennifer Carlson.
Sierra Nevada red fox bounds back to its native habitat after capture and study. CDFW photo by Scientific Aide Corrie McFarland.
The Sierra Nevada red fox has been the subject of intensified study by CDFW over the past decade. As they are notoriously tough to track and even tougher to trap, there are many unanswered questions regarding this elusive animal.
In an effort to better understand this state-listed threatened species, an ongoing research project seeks to capture and affix GPS tracking collars to them. The data collected will help biologists better understand the size and characteristics of the fox’s home range, its denning and resting areas, and its foraging habits.
The species has been outfoxing researchers for some time -- to the point where in the 1980s, it was presumed to have vanished forever from its historically occupied habitat in the Cascade and Sierra Nevada ranges. In March 1993, thanks to the then-emerging technology of infrared trail cameras, US Forest Service employees detected a single red fox in the Lassen National Forest.
That discovery prompted a wider study of foxes and other meso-carnivores in and around Lassen Volcanic National Park. In the late 1990s and early 2000s, Dr. John Perrine of the University of California, Berkeley, captured five individuals, primarily in the park, and placed radio collars on them to study their home range (both summer and winter), food habits and resting sites. Unfortunately, two of the collared individuals died within a year and none of the females reproduced during the course of the study.
Years later, CDFW launched a new study to determine the foxes’ current distribution in northern California and to address potential impacts on the species from activities including recreation and timber harvest. Initial efforts in 2008 used scat-detector dogs to survey portions of Lassen Volcanic National Park and the adjacent Caribou Wilderness. Then, from 2009 to 2011, trail cameras and hair-snaring devices were employed to survey high-elevation habitats in the Cascade Range from Mount Shasta to Lassen Peak. Yet foxes were only detected in the Lassen Peak area.
CDFW biologists have continued to survey for foxes with trail cameras, hair-snaring devices and scat surveys. Scats and photos are often obtained along Lassen Volcanic National Park and Forest Service hiking trails, because, like many other animals, red foxes frequent trails as they move through their territories. Analysis of the DNA contained in the collected scats and hair identified 22 individuals from 2007-2016. Some of these foxes are long-lived – samples collected over time from the same individual indicate that five of those individuals lived at least five and a half years.
CDFW efforts to capture and collar Sierra Nevada red foxes since 2013 were unsuccessful – until early February 2018. The nearly two decade-long dry spell came to an end at last when CDFW captured a Sierra Nevada red fox, a male that weighed about 10 pounds. It was captured in a “log cabin” style trap on National Forest land just outside of Lassen Volcanic National Park, near the town of Mineral. The fox was collared and released at the capture location, and CDFW biologists have been impressed by the distances he has regularly been covering since (five to six miles per day) despite the rough terrain and high elevation.
“Persistence played a large role in our success, because there are many days when we do not have any fox detections,” said CDFW Wildlife Biologist Jennifer Carlson. “We also ramped up our efforts this year by hiring two scientific aids rather than just one, which allowed us to literally double our efforts by putting more traps out across the study area.”
CDFW hopes to capture as many as four more red foxes this year. Scientists are using box traps, cage traps and a “log cabin” style trap that researchers have used in other states to capture both red foxes and wolverines. Capturing foxes is not an easy task given the cold temperatures and snowstorms, but as the Lassen population may only consist of around 20 individuals, it is imperative for the department to learn as much as it can about this stealthy animal.
For more information, please visit the Sierra Nevada red fox page.
Top photo: Senior Environmental Scientist Pete Figura and Senior Wildlife Veterinarian Deana Clifford release a red fox study subject. CDFW photo by Corrie McFarland
These pregnant females will bolster the population of a newly established herd as well as provide an infusion of fresh genetic material to helps ensure their new herd’s health and long-term survival.
Outfitted with an ear tag and two tracking collars, this ram awaits delivery to a new herd where it’s hoped he will infuse the population with fresh genetics
Among the goals of the Sierra Nevada Bighorn Sheep Recovery Plan is the establishment of 12 viable herds across their historic range. CDFW’s capture and relocation efforts over the years have helped establish 14 herds today across 150 miles of their historic range.
These Eastern Sierra bighorn sheep are being prepared for their flight to a new home and new herds.
Can just seven Sierra Nevada bighorn sheep really make much of an impact on the species’ future?
CDFW scientists believe so, which is why they came away pleased with the results of their annual spring helicopter capture this past March. Limited to three days of work due to strong winds and bad weather, the effort resulted in the capturing, collaring and relocation of seven sheep to new herds high in the Eastern Sierra.
Although the final chapters have yet to be written, the saga surrounding the Sierra Nevada bighorn sheep, one of the rarest large mammals in North America, is shaping up to be a 21st century wildlife success story.
A unique subspecies found only in the Sierra Nevada, historic populations numbered in the thousands. Their steep population decline began in the 1800s as a result of competition from livestock grazing, unregulated hunting and the transmission of disease from domestic sheep. Drought and predation further hammered their numbers, which dwindled to about 100 animals in just three herds by the mid-1990s. State and federal officials declared them endangered in 1999.
Today, less than 20 years removed from those dramatic listings, there are 14 different Sierra Nevada bighorn sheep herds spread across 150 miles of the iconic mountain range. About 600 bighorn sheep are now eking out a living atop the Sierra’s highest peaks. Sierra Nevada bighorn sheep are present once again inside Yosemite National Park and Sequoia National Park after a 100-year absence.
CDFW’s role is itself unique as a state agency tasked with leading the recovery of a federally listed endangered species. Sierra Nevada bighorn sheep are recolonizing their historic range – with a major assist from CDFW’s twice-yearly captures, collaring and strategic “translocations.”
This spring, three males and four pregnant females were captured from two established herds and translocated to two newly reintroduced herds – one along their western range inside Sequoia National Park and another herd in Inyo County at the southernmost extent of their range.
“Whenever we start these new herds, we like to move a minimum of 20 females as well as additional rams over time,” explained Tom Stephenson, a CDFW senior environmental scientist based in Bishop and the leader of the Sierra Nevada Bighorn Sheep Recovery Program. “At that point, we feel the population has enough animals to begin growing at a high enough rate and also has sufficient genetic diversity.”
Before the animals are relocated, a CDFW team records their vital statistics. Ultrasound machines are used to measure body condition and determine pregnancy status. The animals are outfitted with identifying jewelry – color-coded ear tags, VHF and GPS collars that allow biologists to identify them and track their movements for years in some cases.
All the high-tech, intensive monitoring has paid dividends with new appreciation and understanding. Once believed to always migrate to lower elevations in the winter, CDFW scientists have learned that many sheep ride out the Sierra Nevada’s inhospitable winters at 11,000- to 14,000-foot elevations.
“They are really tough,” Stephenson said. “But they’re able to do that because they put on large amounts of body fat in the summer when they’re on quality habitat. They are essentially hibernating standing up in the alpine. They’ve got an environment up there that is wind-scoured so they can find some food. They’re not having to move around much, and they’re relatively free from predators when they’re up in those altitudes in the winter time.”
Not every sheep captured is relocated.
Helicopter crews this spring attempted unsuccessfully to capture rams in the northernmost part of their range, collar them and return them to their same herds. CDFW biologists are keeping close tabs on the Mount Warren Herd near Lee Vining in Mono County in particular and its proximity to domestic sheep grazing on public land. Sierra Nevada bighorn sheep are disease-free and CDFW biologists want to keep them that way.
While populations have met or exceeded some recovery goals, eliminating disease – or the risk of disease – remains a significant benchmark and key to delisting or down-listing the species from endangered status.<
“There are a lot of bighorn sheep populations throughout the West that continue to struggle with disease,” Stephenson said. “So we’ve worked really hard with public land managers as well as private individuals in the Eastern Sierra to try and ensure our bighorn sheep don’t come into contact with domestic sheep.”
CDFW photos courtesy of Andrew Di Salvo. Top Photo: A helicopter crew delivers four bighorn sheep to CDFW's base camp where vital statistics were recorded, blood was taken, and the sheep were outfitted with identifying ear tags and tracking collars.
It does not take a leap of faith to believe that CDFW scientists have gained the upper hand in bolstering the population of yellow-legged frogs in the High Sierra.
Over the past three decades, Sierra Nevada yellow-legged frogs have become imperiled in California due to the two-pronged impact of introduced (non-native) trout and chytridiomycosis, a disease that is affecting amphibians worldwide.
Past introduction of non-native fish, including rainbow trout and golden trout, to benefit sport fishing in the High Sierra took a heavy toll on the species. High-elevation lakes where these frogs once flourished were largely fishless until fish stocking came into vogue. As the years passed, scientists determined that these introduced fish were depopulating the frogs by competing for food sources (primarily insects) and by predation (trout ate both adult frogs and their tadpoles). Chytridiomycosis, which affects many frog species, also impaired the ability of the Sierra Nevada yellow-legged frog’s skin to exchange vital nutrients, which often leads to death.
As a result, Sierra Nevada yellow-legged frogs are believed to have vanished from approximately 92 percent of their historical habitat, and halting and reversing that decline has become an important goal of CDFW, as well as other state and federal entities.
“This is an animal that only lives in the Sierra Nevada,” said Sarah Mussulman, a CDFW senior environmental scientist. “It is one of our unique California species that lives in high-elevation areas, and as an amphibian it serves as an important link between the terrestrial and aquatic ecosystems. This link is especially critical in the low nutrient, granitic basins of the High Sierra, where frogs and tadpoles consume insects and algae and are themselves consumed by a variety of snakes, birds and mammals.”
CDFW recently completed two projects as part of its ongoing efforts to reverse the population decline of Sierra Nevada yellow-legged frogs.
The efforts took place at two sites: Highland Lake and Clyde Lake, located approximately seven miles apart on the Rubicon River in the Desolation Wilderness area of El Dorado County. The projects were completed with federal grant funds earmarked for the recovery of endangered and threatened species (the species is listed as threatened by the State of California and as endangered by the U.S. Fish and Wildlife Service).
Highland Lake, along with its outlet, an unnamed stream, and two small adjacent ponds, supported a small population of rainbow trout when the project began in 2012. Trout abundance had declined in the absence of stocking in recent years but sufficient natural reproduction occurred in the inlet to Highland Lake to sustain the population. CDFW began using gill nets to remove rainbow trout -- the descendants of fish planted in the lake by CDFW from 1935 to 2000 -- in 2012, in partnership with Eldorado National Forest personnel.
During a frog-monitoring survey at Highland Lake in 2016, approximately 800 adult frogs were observed, as compared to a 2003 survey in which only a few tadpoles were observed. Because the frogs have consistently survived in this area despite the presence of chytridiomycosis, scientists believe they have a good chance at persisting in the area for a long time.
“Highland really had a population explosion over the past five years and can be counted as one of the most successful projects of this type ever undertaken,” Mussulman said.
The project at Clyde Lake was smaller and had somewhat different factors.
Golden trout, which frequently have the same negative impacts on Sierra Nevada yellow-legged frogs as rainbow trout, including predation and competition for food sources, were planted by CDFW at Clyde Lake from 1932 through 2000.
Once stocking was halted, the golden trout proved less resilient then the rainbow trout at Highland Lake, due to habitat factors.
“Clyde Lake sits in a north-facing granite bowl bordered by 1,000-foot cliffs, and no flowing streams enter the lake,” explained Mussulman. “There was no spawning habitat, which is likely why golden trout did not persist there after stocking was halted.”
The stream flowing out of Clyde Lake and four nearby ponds did support a small population of golden trout after plants were halted. The fish in the stream and ponds, which are self-sustaining populations, are precluded from moving from the stream into Clyde Lake by a fabricated dam. In 2013, frogs and a few tadpoles were observed in the stream alongside fish, and CDFW began removing the fish from the stream with gill nets to provide additional habitat for the frogs.
Nine years of monitoring data collected by CDFW scientists indicate that the area’s Sierra Nevada yellow-legged frog population, while small, is slowly increasing. Surveyors observed more than 120 frogs in 2016, compared to a low of six observed in 2005. Moreover, in 2016, for the first time, dozens of tadpoles were observed in the newly fish-free lower reaches of the stream.
“It is great to see these populations recovering,” Mussulman said. “It is a great privilege doing this work that helps keep these frogs on the landscape.”
CDFW photos: Highland Lake in the Desolation Wilderness, and a Sierra Nevada yellow-legged frog
Deer population estimates are an important element of the California Department of Fish and Wildlife’s (CDFW) management decisions regarding the species – including setting quotas for deer-hunting seasons, acquiring land and identifying habitat improvement projects. Historically, CDFW has relied upon helicopter surveys to obtain these population estimates, but such surveys can be problematic. While they are effective in open and largely flat areas, they are less so in tree-laden areas where deer are hidden from sight. They can also be extremely expensive.
Now, thanks to emerging DNA technology, scientists are exploring a less invasive, cost-effective alternative: Analysis of what the deer leave behind.
The use of DNA is not new, of course – CDFW has used hair or tissue samples to extract DNA and identify individual animals for years. But scientists are finding that the painstaking collection and analysis of deer droppings is particularly useful because it allows them to gather the necessary information without physically touching (or stressing) the animals. And that, one might say, is the “bottom line.”
Fecal DNA analysis is being used by wildlife biologists in the North Central Region as part of a six-year region-wide study of mule deer (Odocoileus hemionus) that will provide population estimates in areas where data has previously been lacking. CDFW scientists, in cooperation with UC Davis, will use the deer pellets to take a genetic “fingerprint” designed to help estimate deer populations.
Starting in 2016, a crew began setting transects for pellet collection in the standardized sampling locations (known to hunters as deer zones X6a/b, X7a/b and X8) which are located in Lassen, Plumas, Sierra, Nevada, Placer and Alpine counties. After starting points were randomly selected, habitat information and pictures were collected along with fresh pellets. After the pellets were removed from the area in an initial sweep, scientists revisited the transect once a week for three more weeks to collect new samples. Between July and September of 2016, biologists visited 43 different transects in the summer range and collected and analyzed 458 fresh pellet samples. Staff also captured 20 does and seven bucks and fit them with satellite collars that produced data that helped identify summer home ranges.
CDFW will also use DNA to identify individual deer to help gather buck/doe/fawn ratios. Biologists will then combine the DNA data with home range data from collared deer to calculate the estimated number of deer in the population. This year staff have already completed another 36 plots and collared 18 more deer. Another series of pellet collections is scheduled next year, with a goal of continuing until all 17 counties in the region have been sampled.
Although several DNA projects are occurring across the state, this project is the largest landscape-level study for deer in California. The study is funded through CDFW’s Big Game Account, a dedicated account that provides research and management funds for game species. The University of California will conduct the laboratory work and statistical analysis.
Porcupine1: NRVP participants Greg Moore, Mike Maulhardt, Charles Brown and Ben Smith volunteered to service and maintain porcupine stations at Red Lake Wildlife Area.
Not to put too fine a point on it, but studying California’s porcupines hasn’t traditionally been a high priority for CDFW.
Wildlife research funding is limited, especially for non-game species, and species listed as threatened or endangered are typically given top priority. That means that scientists sometimes need to be creative – and frugal – in their efforts to survey and manage non-listed, non-game species.
Stacy Anderson, a CDFW senior environmental scientist specialist based in Rancho Cordova, recently conducted a pilot project that does just that.
Anderson developed an interest in the North American porcupine (Erethizon dorsatum) in 2017, after acknowledging that anecdotal evidence seems to indicate their numbers are on the decline.
Porcupines have historically inhabited diverse habitats including Humboldt County, along the Sacramento River, in the Coast Ranges, the Klamath Mountains, the southern Cascades, the Modoc Plateau and the Sierra Nevada. But in her conversations with unit biologists and wildlife officers in some of these areas, Anderson took note that many were reporting a substantial decrease in the number of calls from residents whose property – typically wood structures such as decks and outhouses – had been damaged by porcupines in recent decades. Informal surveys of veterinarians across the state also indicated a decline in the number of pet owners seeking quill removal from their pets.
Perhaps most telling, CDFW’s Sierra Nevada monitoring project, which has studied portions of the Sierra for the past nine years, has documented only seven porcupine sightings out of 750 stations surveyed via trail camera.
“We are worried about them because we don’t have a lot of sightings,” Anderson said. They live in low densities and they have only have one baby per year, so they don’t repopulate quickly.”
Recognizing the need to gather more information, Anderson and Evan King, another CDFW environmental scientist, launched a pilot effort last year to improve surveillance of porcupine, with a long-term goal of determining distribution and population numbers.
Anderson and King were inspired by the work of Uldis Roze, a researcher who has long studied porcupines in the Catskills of New York by using wood soaked in salt brine as a porcupine attractant. His research indicates that porcupines show a strong seasonality of salt use, which peaks in April through May and August through September. Because porcupines’ diet of plant matter is generally low in sodium (salt), they seek out other dietary sources of sodium to maintain normal levels in their bodies.
Anderson and King theorized that brined wood could be effective in attracting California porcupines, too. A plan was made to soak stakes made from 2x2s in a sodium brine to monitor activity. In theory, tooth scrapings on the wood could also be identified to species.
“It’s not a full-blown study – it’s just a way to test a plan of action that can maybe be used in a study later,” Anderson explained. “We don’t want to waste valuable resources on untested methodology, so this is a way to find out first if the methodology is going to work. It’s a low-cost, high yield approach.”
Twenty-three stations were set up for the 2017 pilot project, which was conducted from April to October. Members of CDFW’s Natural Resources Volunteer Program, who support departmental operations, supplied much of the labor, and the study costs were kept low. Expenses added up to less than $100, including salt for brining and wood. Trail cameras borrowed from other researchers were utilized to help monitor the stations.
Researchers were pleased to learn that the porcupines took to their efforts with a grain of salt (so to speak). They determined that brined-wood monitoring is more effective than traditional bait or game-trail monitoring, at least in the study area in northern Sierra and along the Sacramento River. Preliminary results indicate that the brined wood appeared to lure porcupines into the area of a camera station -- although most did not approach the wood and fewer still left a distinctive chew mark on the brined wood. But the trail cameras provided clear, useful photographs.
“We still have unanswered questions about this technique that will need to be addressed before we can consider it a success,” Anderson said. “However, our pilot efforts are promising.”
CDFW is seeking additional funding through state wildlife grants and collaborative efforts with other researchers and agencies to gain a better understanding of the North American porcupine’s status. Anderson plans to continue refining the methodology of her study, along with other survey techniques including habitat surveys, feeding signs, tree girdling, scat searches and the use of detection dogs.
Anderson also encourages members of the public to help CDFW’s efforts by reporting detections of live or “roadkill” porcupines.
CDFW Photos. Top Photo: Porcupine photo by CDFW Warden Chad Alexander.
This summer marked the end of an incredible journey for four dozen of California’s designated state freshwater fish, the golden trout, as they returned home after 10 months away. The fish traveled more than 500 miles in tanks and buckets, by hand and by mule, en route to their native waters 9,000 feet up in the Sierra Nevada range.
The journey began last fall after CDFW scientists observed that ongoing drought conditions were severely impacting the rare trout’s mountainous habitat. A decision was made to rescue 52 fish – a representative population that could repopulate the stream and save the species if drought conditions worsened.
Golden trout are one of California’s most iconic trout species. They are native to only two stream systems in the southeast Sierra Nevada – Golden Trout Creek, and the South Fork Kern River in Tulare County. Volcanic Creek, which is home to the rescued fish, connects with Golden Trout Creek during runoff and high-water level years.
The journey began in September 2016, when fisheries biologists made the two-day trek into the mountains to gather the trout. The captured fish were transported to the American River Trout Hatchery near Sacramento, where technicians monitored them, often around the clock. After nine months at the hatchery, the fish were ready to start the long trek back to their home waters. Crew members transferred the fish from the hatchery to a fish tanker truck and hauled them more than seven hours overnight to the trailhead at an elevation of 10,000 feet in the southern Sierra.
The crew met up with a CDFW team that would escort the fish on horseback, 16 miles into the Inyo National Forest. Federal laws forbids motorized vehicles on wilderness land, which left the team no option but to transport the fish by mule train in fish cans.
The operation took tremendous teamwork from multiple divisions in CDFW and the National Forest Service. Ultimately, the CDFW team successfully returned 48 fish to their natural element. Four died in captivity over the winter. CDFW officials consider that a normal mortality rate. Scientists remain optimistic that these iconic fish will continue to thrive and perhaps even be on-track for a brighter future.
See related VIDEO.
For generations, anglers in California’s eastern Sierra Nevada mountains fished for one of the most cherished fish in the west, the Lahontan cutthroat trout (LCT). These native beauties are prized for their size, with some growing as large as 40 pounds in the Tahoe Basin.
Sightings of these brown and red native fish have been documented as far back as 1853. But as the population of the state grew, especially during the Gold Rush, the fish were nearly wiped out by mining, development, dams, water diversion and other human factors.
Today, LCT are listed under both the State and Federal Endangered Species Acts, and CDFW has increased its commitment to angling enthusiasts by providing more opportunity to catch this historic fish. This effort includes greatly expanding the number of waters and fish planted in recent years.
Every spring, staff from the American River Hatchery in Gold River make the 100-mile journey from the hatchery to the tiny spawning buildings on the shore of Heenan Lake. This pristine body of water is surrounded by granite peaks in remote Alpine County. It is usually not accessible in the winter, cut off by the snowpack, and is only open to catch and release fishing for six weeks a year. It is also the state’s only source of LCT broodstock (groups of mature fish used as the source for eggs and reproduction). Ultimately, the 800,000 eggs spawned at Heenan Lake each year support recreational angling opportunities at multiple locations in the eastern Sierras.
The staff will make the journey up and down the mountain several times over several weeks to spawn the eggs on site. The process involves carefully bathing the eggs in iodine and suspending them in cheesecloth in aluminum jars about two feet tall, before making the journey back to Sacramento or to other state hatcheries. Some of the eggs head to destinations as far away as Filmore Hatchery in Ventura County.
Once at the hatcheries, the eggs are placed in “hatching jars,” where chilled, UV-filtered river water circulates over them continuously. After two to three weeks, the eyes of the baby fish are visible inside the eggs. These “eyed” eggs will be addled—a process in which the eggs are siphoned through a tube in order to shake them up. This causes the infertile, diseased or dead eggs to turn white, allowing hatchery technicians to easily identify, pick out and discard them. After the fry hatch, they are moved to deep tanks in the hatchery building, where they will spend approximately five months growing before being moved outdoors to large round tanks.
The fish will be planted as fingerlings or sub-catchables (fish that weigh 1/16th-1/6th of a pound) into various high-mountain waterways on the east side of the Sierras. At the time of release, they are still too small to be caught, but they will quickly grow to be trophy-sized fish for the state’s anglers who want to make the journey into the high altitudes.
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