Science Spotlight

As Californians continue to face devastating wildfires, researchers are lending their expertise by producing data to inform fire policy.

CDFW contributed an article to a recent special-edition journal featuring fire studies from around the world. CDFW’s paper shows that a mix of fire intensities, and low severity fires in particular, promote a diversity of forest carnivores like bears, fishers and bobcats. The results of the study support the value of prescribed burning in advancing ecological and societal objectives including wildlife diversity and human health and safety.

“Wildfire is a natural part of the landscape, and we probably can’t stop it,” said the paper’s lead author, CDFW Senior Environmental Scientist Dr. Brett Furnas. “But prescribed burning is a tool we have to mimic low severity fires, which are less destructive. It’s a win-win because low severity fires have the added benefit of improving biodiversity.”

Dr. Furnas and his team conducted the research by analyzing data from 1,500 camera traps that have been placed by scientists in Northern California forests since 2009.

“We pulled together a large data set and compared the occurrence of 15 species of forest carnivores — including bears, fishers and bobcats — to the fire history of the landscape during that time period. The study shows our forest carnivores are well-adapted to low severity fires,” said Furnas.

Unlike high intensity fires which tend to eradicate all trees in a given area, low intensity fires tend to thin out forests and burn mostly the understory. Prescribed burning mimics the effects of low intensity fires which are associated with ecological benefits. Other research has shown that mixed intensity fires in California have ecological benefits for birds, bees and plants.

“The goal of the study was to use science to help inform conservation decisions,” said Furnas. “The science can help policy makers decide the best course of action and how to balance the needs of the state.”

Media Contact:
Ken Paglia, CDFW Communications, (916) 825-7120

Some of the 160 people who assisted Fish and Wildlife with it's March 1 desert bighorn sheep survey. CDFW photo.


Charles and Nicole Lozano of Chino Hills using binoculars and a spotting scope to locate sheep. CDFW photo.


The San Gabriel Mountains, north of Ontario, where the sheep survey took place. CDFW photo.

The San Gabriel Mountains, north of Ontario, are a spectacular location for those who enjoy steep hikes and beautiful scenery. But one Sunday each year, those mountains are visited by people with a more specific agenda. They’re there to assist environmental scientists from the California Department of Fish and Wildlife in determining the number of desert bighorn sheep living there.

On March 1, 2020, about 160 volunteers gathered near the rugged terrain for the annual sheep count. Their goal was to use spotting scopes and binoculars to locate sheep, and determine and record their gender and approximate age. The volunteers attended a mandatory training session the night before in which CDFW staff briefed them on the purpose, counting techniques and best gear and supplies to bring for what can be a long day in tough elements. And as it turned out, March 1 was the one day in a stretch of about 20 that included a forecast of rain, and the forecasters nailed it. Between the fluctuating poor conditions – including a steady rain, low clouds, strong winds and even hail – nearly every volunteer struck out on being able to locate any sheep.

Fortunately, the annual count also includes an aerial survey the day before the boots-on-the-ground effort, and the weather was cooperative on Feb. 29. Eight CDFW employees took turns that Saturday flying in a Bell 407 helicopter over the locations where they’d likely find the sheep groups. Flights were limited to 2.5 hours before refueling was necessary. The crew of three on each flight was responsible for taking notes and guiding the pilot, using a handheld GPS to drop a waypoint at each observed sheep location, and capturing the animals with camera gear. The doors of the aircraft were removed to improve visibility for the spotters.

CDFW Senior Wildlife Biologist and survey coordinator Jeff Villepique said a key element of the effort is determining the health of the younger animals.

“One of the things we look at is how many lambs from last year have survived to this year,” said Villepique. “We did get some decent numbers that will help us determine the recruitment ratio and give an indication that the population is growing and doing well.”

When CDFW first started conducting these counts in 1979, the desert bighorn sheep in the San Gabriels numbered about 740. That dropped to fewer than 200 in the late ‘90s, and currently the population is back up to about 400.  Villepique said the numbers rise and fall based on food availability, habitat loss, weather patterns and the history of wildfires.

One group that enthusiastically supports the survey is the Society for the Conservation of Bighorn Sheep. Volunteer Debbie Miller Marschke has joined the effort multiple times, and despite the lousy weather conditions, was happy to be out in the mountains once again.

“When you get out in the environment and you’re with positive people, it’s not a wasted day, it’s a memorable day,” Miller Marschke said, smiling as she braved the downpour. “If I stayed home, I wouldn’t remember what I did a month later. I’m going to remember this day all year long.”

Logan Weyand, left, a veterinary student form Washington State University, and Drew Trausch, a scientific aid with CDFW’s Big Game Program, help capture and collar a cow Roosevelt elk in Humboldt County this past fall. CDFW photo by Shwn Fresz.


CDFW crews work quickly to tag and collar a tranquilized cow elk in Humboldt County. CDFW photo by George Harse.


Sporting ear tags and a GPS tracking collar, a cow Roosevelt elk returns to heavy timber after being sedated. CDFW photo by Andrew Trausch.


Ear tags provide biologists with visual identification of Roosevelt elk study animals while GPS tracking collars can provide years worth of detailed date on movement and habitat preferences. CDFW photo by George Harse.

State biologists are now learning a great deal about California’s largest land mammal.

Roosevelt elk are one of three subspecies of elk native to California, joining the tule elk (the smallest of the three) and the Rocky Mountain elk. While a bull Rocky Mountain elk will have larger and more impressive antlers, the Roosevelt elk bests it in body mass. A bull Rocky Mountain elk can reach 700 pounds while a bull Roosevelt can exceed 1,000 pounds.

Despite their massive size and majestic appearance, Roosevelt elk have proved an elusive research subject because of the dense forests they inhabit. Aerial surveying and trapping – standard tools for counting and collaring deer, elk and bighorn sheep in more open parts of the state – can be challenging for Roosevelt elk moving in and out of heavy coastal timber.

While deer often can be darted and tranquilized using a biologist’s truck as cover, Roosevelt elk are more wary and vehicle-shy, often requiring a lengthy stalk and serious hunting skills to get within the 50-yard effective range of a dart gun. In some cases, it can take more than 100 hours to capture and collar an individual Roosevelt elk.

In an attempt to close the knowledge gap, CDFW recently initiated one of the largest Roosevelt elk capture and collaring efforts in state history, targeting a population of Roosevelt elk living along the U.S. 101 corridor in Humboldt and Del Norte counties. The effort is part of an ongoing study that began in 2016, explained Carrington Hilson, CDFW’s lead elk research biologist on the north coast. The study will continue through 2025.

Since November, Hilson and her colleagues have affixed GPS tracking collars on 24 cow Roosevelt elk in Humboldt and Del Norte counties to monitor their movements and migrations. CDFW biologists plan to collar another 14 cows this winter.

Several ancillary projects – estimating populations using fecal DNA, looking at calf survival and understanding habitat use – are also underway at Humboldt State University in Arcata in coordination with CDFW that will add to the state’s body of knowledge.

A few factors are driving the research interest, explained Kristin Denryter, the Sacramento-based senior environmental scientist who oversees CDFW’s Elk and Pronghorn Antelope Program. The first is an increasing number of human-elk conflicts along the U.S. 101 corridor that include vehicle collisions, property damage and agricultural losses suffered by north coast farmers and ranchers.

The second driver is technology. Advances in GPS tracking collars make them an increasingly valuable research tool. The new elk collars will record data every six hours over the life of the study and deliver that information daily to CDFW biologists.

Lastly, there is the California Essential Habitat Connectivity Project and U.S. Department of the Interior Secretarial Order 3362 (SO 3362).

Signed in 2018, SO 3362 directs federal agencies to work with California and other western state wildlife agencies to improve the quality of big-game winter range habitat and migration corridors on federal land. The order provided funding for CDFW to acquire the 38 GPS tracking collars and accelerate its research efforts. The collar data will improve understanding of movement and habitat use to inform habitat enhancement on public lands as well as help guide development of potential crossing structures to not only improve habitat connectivity but to also improve public safety by reducing vehicle collisions. CDFW has partnered with CalTrans on improving connectivity as part of the California Essential Habitat Connectivity Project.

A Roosevelt elk stakeholder group made up of CDFW representatives, tribal interests, farmers, ranchers and local officials is also being developed.

Official estimates put the Roosevelt elk population along the U.S. 101 corridor in Humboldt and Del Norte counties at 1,600 animals. Biologists, however, suspect those estimates to be low. In an attempt to reduce growing human-elk conflicts, CDFW issued 20 additional Roosevelt elk tags during the 2019 hunting season through its SHARE program, which provides public hunting opportunities on private land through cooperating landowners. CDFW is currently petitioning the California Fish and Game Commission to increase the allotment of Roosevelt elk tags available along the north coast in the 2020 fall hunting season.

Translocations, limited hunting, high calf survival, and conservation management have all helped boost Roosevelt elk populations from lows in the early 1900s to a robust statewide estimate today of 5,700 animals. Roosevelt elk also occupy parts of Mendocino, Trinity, Shasta, Tehama and Siskiyou counites.

The U.S. 101 corridor population in Humboldt and Del Norte counties has proved particularly adaptable – as comfortable roaming the beaches of state parks as they are grazing in open alfalfa fields or wandering underneath the forest canopy. That’s made them especially popular with tourists and some locals but not so much with farmers and ranchers suffering property damage and crop losses from the expanding herds.

Forensic Specialists Kelly Carrothers (l) and Ashley Spicer, from the California Department of Fish and Wildlife, remove samples from tusk at the La Brea Tar Pits, in Los Angeles.  

In Southern California, there are two facilities that offer fascinating looks at the types of animals that roamed the land millions of years ago. The Western Science Center in Riverside County is home to 100,000 fossils and artifacts, all unearthed during construction of a nearby reservoir. The La Brea Tar Pits in neighboring Los Angeles County serves a similar purpose, storing a staggering 35 million prehistoric specimens discovered in and around the natural pits that continue to seep asphalt in the area.

Both facilities gladly open their doors to tourists and school field trips. Recently, they also welcomed two California Department of Fish and Wildlife forensic scientists, who traveled from Sacramento to collect samples of ivory tusks taken from Mammoths and Mastodons for a very specific purpose. Ashley Spicer and Kelly Carrothers came to collect the samples to take back to CDFW’s Wildlife Forensics Lab in Sacramento. The lab itself serves a number of purposes. In this case, the staff are collecting ivory samples for DNA testing and identification, under the auspices of a state law (AB 96) that makes it illegal to trade ivory or rhinoceros horn.

The Wildlife Forensics Lab maintains a species database that helps identify the origin of all kinds of ivory samples. The ability to pinpoint the source of any given ivory sample is critical when it comes to prosecuting criminal cases brought against suspected ivory traffickers.

“Mammoth and mastodon are species that are protected under AB 96 – you cannot commercialize them,” explained Spicer. “Examining the DNA allows us to identify the species of origin for any ivory-bearing species -- mammoth, whale, walrus, warthog or hippo. So, we can first distinguish whether a sample is ivory or not ivory, and whether it’s a fake or synthetic. If it is genuine ivory, then we can test it to see what was the species of origin.”

A key element of AB 96 was the closing of a loophole in previous laws. That loophole allowed the continued sale of tusk from mammoths and mastodons, because those animals were extinct. The exemption gave traffickers the chance to fraudulently claim that they were trafficking in legal material. Now that all forms of ivory trafficking are illegal – regardless of whether the species of origin is extinct – CDFW officials hope that an expanded DNA database will be the key to shutting down the ivory trafficking trade in California.

“The laboratory capability we have today helps us differentiate between ivory taken from an elephant that was poached in Africa within the last few years vs. ivory that was from an extinct species like a mammoth or a mastodon,” said Captain Patrick Foy of CDFW’s Law Enforcement Division. “This is huge for us – (now) we can actually prosecute these cases and convict these criminal poachers, to make the cases we couldn’t make 10 years ago,” said Foy.

CDFW is particularly grateful for the opportunity to obtain samples from the two Southern California facilities noted for their extensive fossil collections. “To be able to work with them (Western Science Center and La Brea Tar Pits) is a really exciting collaboration,” said Spicer. “These samples will be used for forensic testing methods, and ultimately for forensics case work that will help preserve some of our most precious natural resources.”

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CDFW Photos. Forensic Specialists Kelly Carrothers (l) and Ashley Spicer, from the California Department of Fish and Wildlife, examine tusk at the Western Science Center in Riverside County.

A tagged Amargosa vole. (National Geographic stock photo)


The “soft release structures” built for the voles were constructed in their natural habitat, giving the captive-bred animals time to adjust to the outdoors. (Photo courtesy of UC Davis School of Veterinary Medicine)
 

Wildlife veterinarians recently hit an important milestone in their collective efforts to conserve a tiny endangered mammal native to the Mojave Desert. The population of Amargosa voles (Microtus californicus scirpensis), restricted to one small town in Inyo County, is now perilously small, due to habitat destruction, climate change and water diversions created to benefit humans. With much of the voles’ natural habitat now decimated, scientists estimate that fewer than 500 currently exist in the wild. (Read the original California Department of Fish and Wildlife Science Spotlight on Amargosa voles).

Co-led by CDFW Wildlife Veterinarian Dr. Deana Clifford and UC Davis Veterinarian Dr. Janet Foley, the Amargosa vole recovery program started in 2012. After the population became nearly extinct in 2014, a captive breeding program was launched at the UC Davis School of Veterinary Medicine as a last-ditch effort to save these tiny creatures, which are a key link in the food chain in their native habitat.

Since the breeding program’s inception, 364 voles have been born and weaned. Several small-scale trial releases have been attempted over the last few years, leading the scientists to identify a clear problem: the animals raised in captivity didn’t necessarily know how to behave in the wild. “The colony animals were a little pampered,” said Foley, referring to the first few trial releases. “They didn’t seem to have the skills to thrive on their own.”

So how to teach a pampered vole to fend for itself? The team members tried several approaches, finally solving an important piece of the puzzle last month. The key was to introduce captive-bred animals to their wild counterparts – and let the former learn from the latter.

The team chose to pair six captive males from the facility at UC Davis with six wild caught females. The voles were introduced to each other for 10 days in temporary indoor cages in Shoshone Village to see which pairs appeared compatible for mating.

Once voles had established pairs, they were moved outdoors. Large dog runs were carefully constructed in their marshland, over the native bulrush that provide shelter and food for the voles. Each run was lined with hardware cloth in order to contain the voles and keep out predators (including coyotes, bobcats, snakes, numerous bird species, bullfrogs, house cats and stray dogs).

For the next 21 days, the new vole pairs continued to get to know each other. Project staff used pit tags – basically telemetry microchips – to monitor their movements and to ensure that they were thriving.

“We used an antenna array around the feeding station, which connects to a computer, so we could watch how they move,” Foley explained. “Most of the time they’re under the bulrush so you can’t see them with the naked eye … but we were amused to see that they’re really not that shy. One male built a tunnel in his natural habitat, but when staff was nearby, he would come out and look right at us before he grabbed food and went back in.”

At the end of 21 days, the kennel doors were opened, allowing the voles to venture out on their own. Foley says that the team was somewhat surprised to see that the pairs generally continued to come and go from the kennels, demonstrating a comfort level with the makeshift shelter. More importantly, at least one of the pairs produced a litter, and several of the other females may be pregnant.

At some point, the team will remove the kennels entirely, at least until the next captive release occurs, likely sometime next spring or summer.

Foley said that she views the July release as a rousing success – not just because the animals are thriving, but because of the body of knowledge the team learned from this experience. “It was really important for us to learn that the colony animals could learn survival skills from their wild counterparts,” she explained. “It was a gamble, and the fact that it worked is so exciting.”

The team will continue to use this technique for the foreseeable future. Ultimately, the goal is to create sustainable populations of Amargosa voles in several different areas. “If there’s a big fire, it could wipe out every marsh in the area,” Foley says. “Our work – and the techniques we are working to perfect -- will help ensure their survival.”

The captive breeding program is one part of a larger joint effort between agencies, universities and nonprofits to save the Amargosa vole. “Together with our partners at the US Fish and Wildlife Service, BLM, UC Davis and UC Berkeley, Shoshone Village and the Amargosa Conservancy, we are conducting habitat restoration, translocations, genetics and health monitoring and community engagement,” Clifford added. “What we’ve learned here not only helps voles, but also helps conserve the other species that rely on these fragile desert marshes.”

Photos Copyright UC Davis School of Veterinary Medicine. Top Photo: One of the recovery team staff members monitoring the vole’s outdoor enclosure during the introductory period. (Photo Courtesy of UC Davis School of Veterinary Medicine)

Media contacts:
Kirsten Macintyre, CDFW Communications, (916) 322-8988
Trina Wood, UC Davis Communications, (530) 752-5257