Science Spotlight

  • September 17, 2021
burned landscape after low severity fire

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

Categories: Science Spotlight, Wildlife Research
  • June 22, 2021
monarch butterfly on a milkweed leaf

A male adult monarch on a milkweed leaf

Scientist Hillary Sardiñas, who works as CDFW’s pollinator coordinator in the Wildlife Diversity Program, recalls a moment several years ago when she showed her young daughter a monarch caterpillar, and realized it’s a species her daughter might not grow up to enjoy.

“It really hit home in a personal way how important it is to conserve the species,” said Sardiñas.

The population of migratory western monarchs has declined more than 99 percent since the 1980s when millions overwintered in groves along the California coast. By the mid-2010s, the population had dropped to the hundreds of thousands. Just a few years ago, scientists estimated there were only 30,000 left. Now there are only about 2,000 migratory western monarchs left statewide.

“Western monarchs may be headed toward extinction in California, and we need to take drastic and immediate action to help recover the population,” said Sardiñas.

Western monarchs overwinter along the California coast from San Diego to Mendocino County, expanding during springtime along the Central Coast and Central Valley. They ultimately migrate into other states west of the Rocky Mountains to breed.

The drastic population decline has been attributed to several factors including habitat loss, climate change and exposure to pesticides. Western monarchs’ overwintering habitats continue to be destroyed or altered by human development, especially along the Central Coast. Development is also reducing nectar resources. Climate change may be causing monarchs to leave overwintering sites earlier than usual and before milkweed, their host plant, has fully bloomed. This causes what scientists call a “phenological mismatch,” meaning monarchs at times don’t have a place to lay eggs and lack the ability to create the next generation in their multi-generational life-cycle.

In addition to population decline, scientists are seeing a new and possibly dangerous phenomenon—an increase in resident monarchs that remain along the coast year-round and don’t migrate. These monarchs are encouraged to stick around by a non-native milkweed which allows them to breed all throughout the year. The phenomenon might seem like a novel adaptation, but scientists are finding that resident monarchs can have up to 10 times the occurrence of a protozoan parasite known as OE (Ophryocystis elektroscirrha). OE can be transmitted through contact with milkweed leaves, and leads to wing deformation, poor health, decreased reproductive ability or death.

To conserve the population, CDFW is taking action on several fronts:

  • In partnership with the Western Association of Fish and Wildlife Agencies, CDFW helped develop a 50-year management plan for western monarch conservation, published in 2019. Two major focus areas of the plan are management of overwintering sites on the California coast and restoration of breeding and migratory habitat in the Central Valley.
  • In partnership with nonprofit River Partners and with funding from the Wildlife Conservation Board’s Monarch Butterfly and Pollinator Rescue Program, CDFW is restoring and enhancing 500 acres of land for monarchs and pollinators in the Central Valley.
  • On its properties throughout the state, CDFW is enhancing and restoring 1,500 acres of habitat for pollinators and monarchs through management actions and planting milkweed and nectar plants.
  • CDFW is improving management strategies on four department-owned overwintering sites.
  • CDFW is increasing milkweed availability for habitat restoration projects by collecting seed from our properties and partnering with local nurseries.
  • CDFW is also helping coordinate conservation action among stakeholders by participating in the Rangeland Monarch Working Group and co-leading the Monarch Plant Materials Working group with the Xerces Society for Invertebrate Conservation.

Julea Shaw, an environmental scientist in CDFW’s Lands Program, helps coordinate the department’s conservation and restoration efforts. Through her work, she is often reminded how California residents have a personal connection to the western monarch species.

“I speak to so many people who remember growing up seeing thousands of monarchs. It shows how impactful the species can be and how they capture peoples’ imaginations,” said Shaw.

There are several actions that residents can take to help conserve western monarchs.

First and foremost, residents can help by planting locally native milkweed and nectar plants. When choosing nectar plants, conservationists recommend choosing plants that bloom in early spring and late fall when resources tend to be scarce.

Second, residents can help by reducing or eliminating pesticide use in their own gardens.

Third, monarch enthusiasts can help conservation efforts by participating in community science projects. There are multiple organizations which train volunteers to count western monarchs at overwintering sites. In fact, much of the current data on declines in western monarch populations was collected in part by community scientists.

Finally, a note on captive rearing. CDFW would like to remind California residents that a scientific collection permit is required to handle and/or conduct research on western monarchs. Rearing monarchs without proper training can lead to health problems that further exacerbate the species’ decline. Recent research shows that captively reared monarchs can be weaker, have smaller wingspans, and be less adapted to migrate.

“It’s going to take a collective effort between residents and conservation scientists to turn the species around. We’re diligently working to expand our efforts—but the work won’t be done anytime soon,” said Sardiñas.

CDFW Photo

Categories: Science Spotlight
  • June 21, 2021
Scientist, Michael Mammola holding a fish on a lake with blue sky

Michael Mamola, CDFW’s Statewide Trout Management and Stocking Coordinator, shows off a Lahontan cutthroat trout before its release into Echo Lake earlier this spring.

hand holding a fish for release in a lake
The Lahontan cutthroat trout is the largest inland trout species in the world and the only trout native to the Lake Tahoe Basin.

Visitor fishing off the side of a pier in a lake
Few visitors to Echo Lake pause to fish and probe the waters for the Lahontan cutthroat trout that live within.

fish in a lake
Lahontan cutthroat trout grow large in Echo Lake, El Dorado County, thanks to the large population of forage fish, principally the Lahontan redside minnow.

California anglers looking to target the native but elusive Lahontan cutthroat trout may want to put Echo Lake in El Dorado County on their summer itinerary.

For the past several years, the California Department of Fish and Wildlife (CDFW) has managed the deep blue waters of Echo Lake exclusively as a Lahontan cutthroat trout sport fishery.

That’s the same fish that has turned Nevada’s Pyramid Lake and its monster-sized cutthroats into a global fishing destination and created a cult following at Heenan Lake in Alpine County among fly anglers looking to tangle with a trophy cutthroat.

Located just minutes off U.S. Highway 50 near South Lake Tahoe at an elevation of 7,500 feet, Echo Lake may offer California anglers their best chance to encounter the Tahoe Basin’s native trout species given the combination of an easy drive, a plentiful fish population supported through a generous stocking regimen, and wide-open fishing access without the restrictions on seasons, take or tackle methods found at some other Lahontan cutthroat trout fisheries.

Adding to the overall experience, Echo Lake receives relatively little fishing pressure. The 300-acre lake is best known as a jumping-off point for the southern portion of Desolation Wilderness. Few of those backcountry travelers, however, pause to wet a line at Echo Lake.

“It’s sort of a hidden gem,” says Mitch Lockhart, CDFW’s District Fisheries Biologist for El Dorado, Placer and Nevada counties. “You’ll not be combatting for space to fish here.”

Echo Lake received a recent stocking of 100 brood stock Lahontan cutthroat trout from nearby Heenan Lake. Resplendent in their crimson spring spawning colors, the fish ranged in size from two to nine pounds with an average weight of two to three pounds. CDFW followed up that trophy stocking with a plant of some 20,000 “sub-catchable” Lahontan cutthroat trout in the seven- to nine-inch range.

Echo Lake’s recent history as a Lahontan cutthroat trout fishery resulted from a collaboration between lakeside property owners and CDFW. Cabin owners were seeking improved fishing opportunities given recent cutbacks and elimination of hatchery stockings of rainbow trout, brown trout and brook trout. At the same time, CDFW fisheries biologists were looking for suitable locations to stock Lahontan cutthroat trout into their historic range in the Tahoe Basin and expose more anglers to the unique, native fish.

Echo Lake fit the criteria. Its steep-sided granite cliffs, clean, cold deep waters are reminiscent of Independence Lake in Nevada County and Fallen Leaf Lake in El Dorado County, two historic and active Lahontan cutthroat trout fisheries.

Echo Lake also is relatively isolated from other waters and protected from infiltration by non-native trout species. The lake holds some small, remnant populations of brook and brown trout with little opportunity for wild rainbow trout to access the lake and colonize it from surrounding waters. Displacement, hybridization and competition from non-native trout is largely what earned the Lahontan cutthroat trout listing under the federal Endangered Species Act 51 years ago and what mostly prevents large-scale recovery efforts today.

And unlike some other high Sierra lakes where trout eke out a meager existence in near-sterile conditions, Echo Lake is rich with food in the form of the Lahontan redside, a native minnow that has proven an important forage fish responsible for Lahontan cutthroat trout growth rates of two to three inches a year in Echo Lake.

Anglers reported catching Lahontan cutthroats to 26-inches last year with the average size being closer to 12 to 14 inches with an occasional 16-, 18- and 24-inch fish in the mix. CDFW biologists say they are seeing anecdotal evidence of natural spawning, but plan to manage Echo Lake primarily for recreational fishing and not species recovery.

CDFW has stocked two strains of Lahontan cutthroat trout into Echo Lake, the Pilot Peak strain of Pyramid Lake fame that can reach sizes in excess of 20 pounds, and the smaller Independence/Summit Lake strain of fish from eggs collected at Heenan Lake and raised at the American River Trout Hatchery outside of Sacramento.

A Lahontan cutthroat trout caught and documented from Echo Lake qualifies for CDFW’s Heritage Trout Challenge, which incentivizes and rewards anglers for catching six different forms of California native trout from their historic drainages.

In addition to easy drive-to access, Echo Lake features a popular marina, boat launch and convenience store where kayaks and canoes can be rented. Private boats and other waterfcraft can be launched only after mandatory inspection and certification that they are free of aquatic invasive species.

CDFW Creates Lahontan Cutthroat Trout Sport Fishery at Echo Lake (Video)

CDFW Photos:

Categories: Science Spotlight
  • May 14, 2021
bobcat on a dirt path

Young bobcat photographed for project, San Diego County

four scientists observing bobcat scat on a dirt path - click to enlarge in new window
Bobcat project staff (left to right) Liam Jasperse-Sjolander, John Nettles, Rudolplh Mena, Jessica Copeland using stick in process of determining if scat came from bobcat

bobcat trail camera on a dirt path with brush - click to enlarge in new window
Bobcat project camera station, Inyo County

bobcat in the snow with brush - click to enlarge in new window
Bobcat in snow, San Diego County

bobcat in sandy path with brush - click to enlarge in new window
Bobcat in sandy terrain, San Diego County

In the field of wildlife management, one of the most common and sometimes most difficult tasks is to obtain information about a particular species of animal in order to properly manage that species. The California Department of Fish and Wildlife (CDFW) was recently tasked by the State Legislature to conduct a demographic study of a particular species of animal that is known to be elusive and generally secretive, bobcats (Lynx rufus).

Officially known as the California Statewide Bobcat Population Monitoring Project, the study is happening because of a bobcat hunting ban that took effect in 2020. Part of the legislation requires the issue be revisited in 2025, but only after CDFW conducts a statewide population assessment, which will then lead to a science-based bobcat management plan.

Performing this study is complicated by a short timeline due to funding and personnel issues. Because the funding and the positions for those hired to conduct the study both end on June 30, 2022, the challenges of accomplishing this study become even greater. The effort began with forming the Bobcat Management Oversight Group (BOMOG), comprised of key individuals from around the state. That team includes the Deputy Director of Wildlife and Fisheries, the Chief of the Wildlife Branch, and key Regional and Program Managers. The BOMOG quickly realized that for the study to be successful, they would need to bring together a team of individuals from around the state. This resulted in the formation of the Technical Advisory Group (TAG), comprised of some of the top scientists and researchers within CDFW.

“The two groups will ensure project staff are employing consistent field protocols and methods, so the project is a success,” said Wildlife and Fisheries Division Deputy Director Stafford Lehr. “Instead of one unit being responsible, the entire department is responsible for this project.”

The TAG was asked to quickly (within two months) develop a study plan to guide the implementation of the study. The group not only met that deadline but also provided a draft capture plan as well as planned and initiated a pilot project to test the plan prior to its full implementation.

“The TAG’s accomplishments in this very short timeline are a testament to their talent and dedication,” said South Coast Regional Wildlife Program Manager and TAG project lead Rick Mayfield. “This project would not have been possible without their hard work.”

With the planning process completed, CDFW hired a team of 20 people specifically for the project. One was Senior Environmental Scientist Rachel Roberts who, as the lead over this group, faces the challenge of implementation and completion of the study by June 30, 2022. At that point, the data collection will end, and the analysis and creation of a statewide bobcat management plan will begin. This plan, due to be completed by January 2025, will cover all aspects of bobcat management, from demographic information to the effects of habitat loss, wildfires and urbanization on the species.

“It’s kind of funny because we know a lot about bobcats and nothing at the same time,” said Roberts.  “We see them in a lot of places and we think that they tend to do well on the edges of urban areas. There have been projects across that state that have collared bobcats, so we have some idea of a home range, but we don’t know specifically all of the different habitats they’re residing in. We have anecdotes of them in orchards, or at high elevations, but that’s one study in one area. This project is trying to get truly to where bobcats are and where they aren’t.”

A few things we do know about bobcats in California: they’re about one fourth the size of a mountain lion, weighing between 12 and 25 pounds depending on environmental conditions. They prey on rabbits, rodents, birds, insects, reptiles and occasionally chickens. Their current population is estimated between 70,000-100,000 statewide. Pelage (fur) markings on their body, legs and face make it possible to distinguish one from another.

To get the most accurate information on California’s bobcat population, Roberts and her team will collect scat samples for fecal DNA analysis. This analysis allows for the individual identification necessary for determining population size via a capture/recapture model. Complementing the scat analysis in assessing the bobcat population, the teams will gather data and photographs in 48 different study areas. Each study area will be 40 square kilometers (just over 15 square miles) and have 80 cameras mounted to record still images of anything that moves in that area, day and night. The motion-activated cameras will shoot images in each study area for six weeks, before being relocated to the next study area.

“We're taking a three-shot, rapid-fire burst with two cameras facing each other at each camera station,” said Roberts. “We're hoping to be able to get photos of the pelage patterns on each bobcat, especially on the insides of their legs – that’s how you can really identify individuals. We're hoping to see these cats more than once so that we may be able to run the capture/recapture model to estimate bobcat density with the camera data as a complement to the scat data.”

“To get their densities and to be able to keep track of individual bobcats, so we know we’re not double-counting them, the DNA in scat is definitely the gold standard,” said Brett Furnas, a biostatistician with the CDFW Wildlife Investigations Lab. “If it’s not a bobcat sample we’re collecting it might be a coyote instead. We confirm that with genetic analysis to make sure what we’re counting is indeed from a bobcat, so we can determine individuals to count them.” Furnas is no stranger to this kind of work. “I’ve worked a lot on deer, so this method of going around and picking up bobcat scat is what we first applied to deer,’ he said. “I’ve also been working with Justin Dellinger (lead of CDFW’s mountain lion monitoring project), so this is the third project in which we’re using genetic information.”

There’s one key difference between the gathering of scat DNA and taking of photographs. Project team members will control how much scat they gather and submit for DNA analysis. Team members won’t have control of the amount of photos that are taken by the nearly 500 hundred motion-activated cameras scattered around the state. The number of photographs to sort through and categorize would be overwhelming, if not for a new company, Wildlife Insights, which stores the images and identifies the animals photographed in the study area.

“All of those photos are uploaded to the cloud and when you open the interface, it has already tagged the animals,” said Roberts. “If it sees turkeys, it has already tagged it. We’re just going in and making sure it’s correct. And, you can just pull out the species that you are interested in. Before, this was all super clunky. We did a pilot study and there were hundreds of thousands of photos, just from two cameras set up for eight weeks.”

Roberts said she’ll visit most of the study areas over the course of the study, but she’d be perfectly happy making it to all 48. The challenge of measuring California’s bobcat population is exactly what she wants to be doing.

Deputy Director Stafford Lehr sees the importance of this work for years to come. “We are striving for a more cohesive approach to applied management throughout the department and we hope this is an improved method of program delivery,” he said. “The importance of having a robust management plan that withstands scientific review and public scrutiny will pay dividends in future programs for the department.”

CDFW Photos

Categories: Science Spotlight
  • May 10, 2021
Bear in a tree

A female black bear takes in her surroundings from the safety of a pine tree after being trapped, tagged and hazed by state parks and wildlife personnel last fall.

As the Lake Tahoe Basin’s black bears emerge from their winter slow-down and slumber, campground managers, biologists, park rangers and wildlife officers hope to have a new tool at their disposal to help manage the human-bear conflicts certain to arise this spring and summer: a growing catalogue of Tahoe’s bear population.

Since the fall of 2019, the California Department of Fish and Wildlife (CDFW) and California State Parks have teamed up to trap, tag and haze as many Tahoe bears as possible to identify individual bears, build a genetic database of the population, study its overall health, and whether related bears are passing down problem behaviors from one generation to the next. Eighteen bears have been trapped to date – four of those being recaptures. Genetic material is collected and each bear is outfitted with an identifying ear tag before release.

This May, CDFW will broaden the effort and team up with the U.S. Forest Service to trap, tag and haze additional bears within the Tahoe National Forest. The trapping takes place in short windows during the early spring and late fall off-seasons at Tahoe-area campgrounds. The bears are hazed – but not harmed – upon release to provide a negative human interaction and to see whether the experience will keep them away from campgrounds and people in the future.

In this video, Shelly Blair, CDFW’s wildlife biologist for El Dorado and Alpine counties, and Sarinah Simons, California State Parks Sierra District human-bear management specialist, explain the innovative collaboration and scientific work during trapping efforts last fall.


CDFW Photo

Categories: Science Spotlight
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