Science Spotlight

The California Fish and Wildlife Journal concludes its 2021 Special Issue installments with the winter quarter’s Special Issue: Effects of Human-Wildlife Interactions on California’s Natural Resources: Conflict and Coexistence (PDF). With this year’s unprecedented drought, unpredictable fire season, climate change, pandemic response, and increased human-wildlife conflict reported statewide, issue 107-3 is salient and timely. In this Special Issue, we explore various interconnected themes across four sections: Terrestrial Predator Interactions, Conflicts & Adaptive Management, Coexistence & Conservation, and the Human Dimensions of Wildlife Conservation.

The California Department of Fish and Wildlife (CDFW) serves as the lead state agency charged with helping to resolve human-wildlife conflict, public safety, and reported depredation (property damage) and committed to advancing discussion and deeper understanding of human-wildlife interactions throughout the state. People live increasingly in close contact with animals, both wild and domestic, as the human population expands along the wildland-urban interface and increases over time. This reality has led to increased human-wildlife interactions and reported  human-wildlife conflict. Negative human-wildlife interactions can directly affect human and wildlife health and may result in loss of livelihood, reduced wellbeing, or in some instances, loss of life – animal or human.

Come read about the various types of human-wildlife interaction, some of the unique challenges – and opportunity – to better address understand and address human-wildlife conflict. Various agency partners, practitioners, researchers, and key stakeholders have contributed their expertise to this Special Issue. We hope you recognize the myriad factors that can shape our perception and approach to wildlife in California. Learn more!

The California Fish and Wildlife Journal has published high-quality, peer-reviewed science for more than 100 years – and the CDFW looks forward to more valuable contributions ahead.

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California is home to more native animal and plant species than any other state in the nation. It also hosts the most endemic species—species that occur nowhere else in the world. However, our incredibly diverse native wildlife is facing an intensifying array of stressors stemming from human activity: habitat loss, new land uses like cannabis cultivation, invasive species, wildfires, drought and so many others. Wildlife managers can mitigate these threats through actions like conserving and restoring habitat, building relationships with private landowners and managing ecosystems for resilience to wildfire and climate change. But, to effectively target management actions, managers need to have high-quality information on wildlife populations across the state.

In two studies recently published in the California Fish and Wildlife Journal, Vol. 107-2 (PDF), researchers with CDFW’s Cannabis Program and Wildlife Diversity Program focused on this need for effective wildlife data collection.

One study focused on monitoring small terrestrial vertebrates, like small mammals, reptiles and amphibians. Traditionally, researchers have monitored these species through live-trapping and visual encounter surveys. But such time-intensive methods are not always feasible. Recently developed methods that use automatic cameras are one alternative. To determine how well cameras perform compared to more traditional methods, CDFW researchers tested two methods alongside each other: 1) visual encounter surveys, where they searched for reptiles and amphibians in a study area, and 2) camera traps, which combined small strips of fencing with close-focus cameras pointed at the ground. They found that the camera system detected far more species of small animals compared to the traditional surveys.

In a second study, researchers compared different methods for monitoring birds. Traditionally, researchers have used point counts, where trained observers identify every bird they hear or see at a location. Researchers are also increasingly using acoustic devices to automatically record bird sounds. Recently, machine learning tools have enabled computers to identify bird sounds from these recordings, allowing people to indirectly identify birds while saving much time and effort. In their study, the CDFW researchers found that low-cost recorders performed comparably to expensive ones, and that a machine learning tool accurately identified high numbers of bird species from the recordings.

The researchers will apply what they have learned and shared to a new statewide monitoring effort, which is being developed by CDFW’s Cannabis Program. These advancements will enable a more efficient wildlife monitoring effort that saves money and time. And most importantly, with the information gained from improved monitoring, CDFW staff and other wildlife managers will be able to make more informed decisions to help our native California wildlife cope with current and future challenges.

Since being signed into law in 1970, the California Endangered Species Act, or CESA, has proved to be a landmark law in a history of progressive wildlife conservation in California. It has been key in helping to stem the tide of species extinctions, raise public awareness about the plight of wildlife, and underscore the need to balance species conservation with economic development. CDFW is responsible for safeguarding the hundreds of CESA-listed species, and a key part of this mission is supporting and elevating the important research being conducted on these imperiled plants and animals.

The 2021 Special Issue of the California Fish and Wildlife Journal titled “The California Endangered Species Act: Successes and Challenges” contains a comprehensive collection of articles about the research, management and conservation of threatened and endangered species. At 473 pages, this is the largest Journal issue ever published! It includes 16 full research articles, five research notes, two review papers and four essays, altogether covering 25 species. Authors include CDFW staff, academic researchers, non-profit organizations and other conservation entities. Download the entire issue (PDF) or individual articles.

Topics covered in the issue include range expansions, new methods for species identification in the field and lab, reviews of habitat use and spatial occurrence patterns throughout California, results of management actions, benefits of long-term monitoring programs and planning strategies for conservation and recovery actions. The issue starts with a CESA Policy and Regulations section and follows with eight sections organized by taxa. Photos at the beginning of each section showcase California’s amazing biodiversity. For those new to CESA, an overview of the listing process is provided both in a detailed article and a simplified flowchart.

Article highlights include:

Amargosa Niterwort

Plants make up 158 of the 316 species currently listed under CESA. In this issue, Amargosa niterwort (Nitrophila mohavensis) takes the spotlight when authors share the value of a 10-year monitoring program for this alkali wetland plant, which occupies a total area less than 20 km2 in the northern Mojave Desert. Collaborative monitoring has resulted in a better understanding of the species, including phenology and abundance trends. This information could support conservation actions in response to threats such as groundwater alteration and off-highway vehicle impacts. For more details, see the article titled “Status of the Amargosa niterwort (Amaranthaceae) in California and Nevada.”

Bumble Bee Protection

In the article “A conservation conundrum: protecting bumble bees under the California Endangered Species Act,” authors Richard Hatfield and Sarina Jepson of the Xerces Society for Invertebrate Conservation present their view of the history and recent context of listing invertebrates under CESA. The authors argue that population declines driven by factors including climate change, insecticides and habitat loss have led to thirty percent of California’s bumblebee species facing extinction risk. In light of this, the Xerces Society and others have led a recent push to provide formal protections for several species of bumblebee. The article provides the authors’ overview of their 2018 petition to protect four imperiled bumblebee species under CESA and the subsequent legal complications that have unfolded.

California Tiger Salamander

“Use of atypical aquatic breeding habitat by the California Tiger Salamander” provides insight into this endangered species’ ability to reproduce outside of its historically associated habitat. Typically thought to reproduce only in vernal pools, researchers observed California tiger salamanders breeding in cattle stock ponds, intermittent creeks and rain-filled excavated depressions. Further investigation is needed to determine if these atypical breeding sites result in any reproductive success, as some have limited hydroperiods that may not be conducive to California tiger salamander metamorphosis. However, this study provides insight for the potential role of reproductive plasticity in the face of vernal pool habitat loss. For development projects within the range of the California tiger salamander, this study identifies additional habitat features that should be assessed when identifying and addressing potential impacts to this listed species.

We would like to thank the CDFW editorial staff for their hard work on this special issue. We also want to thank and acknowledge the researchers and authors of the articles, whose hard work to understand these imperiled species is helping bring them closer to recovery. The California Fish and Wildlife scientific journal has published high-quality, peer-reviewed science that contributes to the understanding and conservation of California’s wildlife for more than 100 years. We look forward to the continued contributions in the next decade to come.

The California Fish and Wildlife Journal concludes the 2020 Special Issue installments with the winter quarter’s Special Wildland Fire Issue. With this year’s unprecedented fire season, and California’s fire-adapted natural communities taking center stage in land management discussions throughout the State and beyond, this issue is especially poignant as we reflect on this past year and contemplate the incoming new year.

Unlike previous Special Issues, this issue is divided into three sections: Vegetation Treatment and Policy, Fire Impacts on Plants, and Fire Impacts on Wildlife and Water. Each section highlights a piece of the wildfire and landscape management ‘puzzle’ through an examination of fire and its impacts on California’s fire-adapted ecological landscape.

One of these unique communities, the Pine Hill Ecological Reserve in El Dorado County, is home to almost 750 plant species, some of which can only be found at Pine Hill due to its unique soil composition. Researchers from CDFW, the California Native Plant Society and Sacramento City College investigate the impacts of different fuel-reduction methods on Pine Hill Ceanothus in “Effects of a firebreak on plants and wildlife at Pine Hill, a biodiversity hotspot, El Dorado County, California” (PDF). The article examines the effects of hand clearing and pile burning on chaparral species within the Wildland Urban Interface and the secondary impacts on wildlife. The study also includes the exciting discovery of new seedlings of Pine Hill Flannelbush, the rarest and most endangered plant in El Dorado county, and a fire-obligate germinator!

Plants that depend on fire to propagate aren’t the only plant communities impacted by the long-term fire suppression practiced in the western United States. New and updated technology is helping landscape managers and scientists study and assess the pre- and post-fire impacts to landscapes using remote sensing and modeling techniques. This type of data collection and analysis helps inform scientists and policy makers on landscape and watershed-level scales and helps focus efforts to manage habitats and sensitive plant communities before and after wildfires. One such effort is presented by Sonoma County scientists in “Sonoma County Complex Fires of 2017: Remote sensing data and modeling to support ecosystem and community resiliency” (PDF). With the help of NASA and other experts the team evaluates the impacts of the 2017 fires to woody vegetation within areas that burned during wind-driven and non-wind driven events to evaluate canopy condition. Using lidar data, the team identifies important predictors for post-fire woody canopy condition, which highlights the importance of high-resolution airborne mapping technology for informing management decisions.

Management decisions include when and how to monitor pre- and post-fire events, and the CSU Monterey Bay’s study “Analysis of the impacts of the Soberanes Wildlife on stream ecosystems” (PDF) highlights the need for monitoring wildfire’s impacts on coastal streams and benthic macroinvertebrate responses to fire events. This monitoring is especially important because macroinvertebrates are the foundation for in-stream salmon and steelhead foodwebs, and the ability of these microscopic organisms to recover from wildfire also impacts the recovery of these keystone species in California’s rivers and streams.

This quarter’s Special Wildlife Fire Issue also includes examinations of impacts and responses of Roosevelt Elk forage in Humboldt County, an essay on the California Vegetation Treatment Program, amphibian responses to wildfire and other topics that span California’s rich ecological diversity.

The California Fish and Wildlife scientific journal has published high-quality, peer-reviewed science that contributes to the understanding and conservation of California’s wildlife for more than 100 years. We look forward to the continued contributions in the next decade to come.

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Media Contact:
Kirsten Macintyre, CDFW Communications, (916) 804-1714

The latest issue of California Fish and Game, Vol. 105, Issue 1 (PDF), focuses on marine species, bringing new insights and understanding of several fish species found off the California coast.

In A very long term tag recovery of a California scorpionfish (Scorpaena guttata) (PDF), Roberts and Hanan report the remarkable recovery of a tagged scorpionfish that had been at liberty far longer than any previously recaptured scorpionfish. The recovery was made during a four-year mark-recapture study on nearshore groundfish off southern and central California. More than 32,000 fish were recaptured, with an average of 408.8 days at liberty. The study results indicate that scorpionfish demonstrate strong site fidelity, given that a majority of the fish were recaptured within 5k of their original tagging site. The scorpionfish that is the subject of the article was tagged in 2004. It had been at liberty for nearly 14 years (5,048 days). After removing the tag, the fisherman who captured the fish reported that he released it “unharmed and looking very healthy.”

Another paper reports on a method for estimating the age of roosterfish using dorsal fin spines (PDF). According to authors Chavez-Arellano et. al, the roosterfish is considered a prized species by the sport fishing community and provides a significant economic benefit to the Mexican tourism industry. However, little is known about its biology, ecology, and movement patterns. The authors embarked upon a study to assess which sections of roosterfish dorsal fin spines have the most legible indicators of growth for use in future aging studies. Their work provides the initial basis from which future aging studies can be conducted.

Finally,Primary and secondary nursery areas for leopard and brown smoothhound sharks in San Francisco Bay, California (PDF), summarizes a 31-year study to determine primary and secondary nursery habitats for leopard and brown smoothhound sharks within South San Francisco Bay, adding new knowledge to the biology of both species.

As it has for the past 105 years, California Fish and Game continues to publish high-quality, peer-reviewed science that contributes to the understanding and conservation of California’s wildlife. We look forward to witnessing the contributions of the next installment.

CDFW Photo.
Media Contact:
Lorna Bernard, CDFW Communications, (916) 322-8911  

The latest two issues of California Fish and Game, CDFW’s long-running scientific journal, are now available online.

Issue 104(3) features a rather dignified-looking desert spiny lizard (Sceloporus magister) on the cover. It is one of 15 species captured and documented by Cummings et. al in Biodiversity of amphibians and reptiles at the Camp Cady Wildlife Area, Mojave Desert, California and comparison with other desert locations. The paper’s eight authors spent months in the Mojave desert location, trapping and identifying its inhabitants. The finding were combined with a review of scientific literature to document the biological diversity of the area in comparison to other desert habitats.

Also in Issue 104(3):

• Annual and seasonal variation, relative abundance, and effects of managed flows on timing of migration in Brown Trout (Salmo trutta) in the upper Trinity River, by Sullivan and Hilemen, challenges a previous study suggesting that brown trout populations are increasing in the upper Trinity River and are having a negative impact on native juvenile anadromous salmonids. The authors assert that previous trapping data suggest a behavioral response to managed flow regimes rather than an increasing population. Further, they provide management recommendations to determine whether the removal of brown trout—an important economic sport fishery resource—is necessary and has the potential to be successful.
• Geographic range and biology of Spinyeye Rockfish (Sebastes spinorbis Chen, 1975), an endemic species to the Gulf of California, Mexico, by Acevedo-Cervantes et. al. The authors add to the existing knowledge of a marine species that is currently not a fishing target and about which little is known.

Issue 104(4)’s cover photo illustrates the article Ground-nesting great horned owl in Suisun Marsh, California. Skalos et. al provide vivid descriptions and photographs of great horned owl nest sites, ranging from non-native eucalyptus trees to man-made structures (such as the dock piling shown in the cover photo) and even ground nests. Though great horned owl nest sites are known to be diverse, little documentation exists to support some of these observations. In fact, Skalos et. al’s ground nest observation is the first documented case in California.

Also in Issue 104(4):

• Prey of neonate leopards Sharks in San Francisco Bay, California by R. Russo. The leopard shark has been the focus of several studies documenting the diet of juvenile through adult stage animals. The author examined the stomach contents of neonate leopard sharks and found that small, easily accessible prey items such as bay shrimps and polychaete worms are important for rapid growth of leopard sharks during the first year of life.
• Within-Talus temperatures are not limiting for pikas in the Northern Sierra Nevada, by Wright and Stewart. Pikas are small herbivores related to rabbits that live in fields of broken rock (talus) in the mountains of western North America. Researchers examined potentially suitable talus habitats at various elevations in the northern Sierra Nevada. Their findings suggest that the cooler temperatures provided by talus is not sufficient to sustain pikas. The aboveground air and surface temperatures, rather than temperatures within talus, pose a greater challenge to pika survival.

California Fish and Game provides important contributions to the existing body of scientific knowledge. First published in 1914, California Fish and Game is the longest continuously published scientific journal. For more information and other back issues, please visit CDFW’s website.

CDFW Photos.

Media Contact:
Lorna Bernard, CDFW Communications, (916) 322-8911

California Fish and Game, Volume 104, Issue 2, is now available online! California Fish and Game is CDFW's official, quarterly, scientific journal devoted to the conservation and understanding of the flora and fauna of California and surrounding areas, and the eastern Pacific Ocean.

A mallard in flight appears on the cover of the newest installment of the journal. With its iridescent green head and school bus yellow legs, the male mallard is one of the most recognizable species of duck in California. It is also the most abundant breeding species of waterfowl in the state. However, California’s mallard population estimates have generally declined since the mid-1990s. In California mallards: a review, Feldheim et. al synthesizes volumes of research in an effort to identify long-term research needs and monitoring activities to help improve management of this iconic species.

In another paper, entitled Abundance, habitat and occupancy of Roosevelt Elk in the Bald Hills of Redwood National Park, Tolliver and Weckerly seek to understand the relationship between a species’ occupancy-abundance rate and its habitat use. Using elk sign surveys (i.e, counting tracks and feces at standardized locations) researchers found that, as population density increases, Roosevelt elk will move into other (lower quality) habitats. This was true for two herds of vastly different sizes, although the occupancy rate remained comparable.

Finally, Hiney et. al looks at recruiting experienced anglers and using citizen science to help document and survey the native Coastal Rainbow Trout population of Grass Valley Creek Reservoir. The authors look at methods of overcoming the time and resource limitations of assessing wild trout populations.

Also included in this issue are reviews of two books that make meaningful contributions to the field of wildlife research.

As it has for the past 104 years, California Fish and Game continues to publish high-quality, peer-reviewed science that contributes to the understanding and conservation of California’s wildlife. We look forward to witnessing the contributions of the next installment.

The latest issue of the scientific journal California Fish and Game is now available online (for free!). Volume 104, Number 1 features a gorgeous photo of a black-tailed jackrabbit in sunlit profile taken by renowned photographer David Jesse McChesney. The back cover image, also by McChesney, features two cottontails at play. We are fortunate to be allowed the use of these amazing images to promote the content of the latest issue. Individual papers in this issue include:

• Reproductive aspects of Sphyraena ensis (Perciformes: Sphyraenidae) inhabiting the coast of San Blas Nayarit, southeast Gulf of California (PDF). The Mexican barracuda is the subject of a study that gathers baseline data for this important fishery resource. Although the species constitutes one of the main economic pursuits along the coast of Nayari, Mexico, little is known about its reproductive biology. A one-year study of specimens caught via commercial fishing revealed that females outnumber males (1:1.87 male:female). They also grow larger—a reproductive strategy that allows them to produce more eggs. By comparing the size of the liver and reproductive organs of the specimens, relative to their overall size, researchers were able to determine that both sexes are at their reproductive peak from April to June. The study results suggest that a fishery closure during this peak reproductive time can provide long-term population benefits for the species.
• Comparison of rabbit abundance survey techniques in arid habitats (PDF). An important component of any species management plan is population data, which is why it is important to know which survey methods are most effective and cost-efficient. Cypher et. al assesses four methods for counting rabbits and hares in arid climates: 1) visual encounter surveys (walking slowly and counting every animal observed); 2) spotlight surveys (driving slowly at night while shining spotlights out each side of the vehicle); 3) aerial surveys (using a low-flying helicopter to flush and count animals along transect routes); and 4) track stations (putting bait in clearings that have been raked smooth, then counting tracks). The results provide interesting observations to consider based upon the individual researcher’s budget, the habitat being studied, and staff time and availability.
• Field method for estimating the weight of tule elk from chest circumference (PDF). Studying larger animals provides an entirely different set of challenges. CDFW biologists frequently capture tule elk for the purpose of relocating them, gathering data and/or providing veterinary care. Administering a proper dose of sedatives and reversal agents is critical for the safety of the animal as well as its human handlers. Since the dosage is based upon weight, the challenge is figuring out how to accurately estimate the weight of an animal that is the size of a full-grown cow. Langner and Casady address this issue by determining a field method for estimating the weight of tule elk. The researchers captured and weighed more than 50 elk over a four-year period, measuring the chest circumference of each animal. The data were analyzed and resulted in a conversion chart that aids researchers in more accurately estimating weights of tule elk in the field.

The latest issue also contains a review of Butch Weckerly’s book, Population ecology of Roosevelt elk: conservation and management in Redwood National and State Parks and a reprint of a scientific paper originally published in 1947 entitled, “Ecology of a cottontail rabbit (Sylvilagus audubonii) population in Central California."

California Fish and Game is CDFW’s official scientific journal devoted to the conservation and understanding of the state’s plants and animals. This issue (either in hi-res or low-res) can be found in its entirety online.

CDFW Photos.

The latest issue of California Fish and Game, the California Department of Fish and Wildlife’s scientific journal, is now available online! Issue 103(4) features articles that add to the knowledge base for three marine species, all of which face potential threats from overharvesting, incidental take and loss of habitat: Thorny stingray, Chinook salmon and green abalone. 

The Thorny stingray (Urotrygon rogersi) (PDF) is common in the eastern Pacific, from the Gulf of California south to Ecuador, and is frequently a by-catch of commercial shrimp trawlers. Little is known about its life history and movements. It was thought to occupy relatively shallow depths ranging from two to 15 meters, with a maximum recorded depth of 30 meters. In their published research, Acevedo-Cervantes et al. report the discovery of specimens at a depth of 235 meters—an indicator that the Thorny stingray has the capacity to survive beneath the disturbance of commercial shrimping activity. According to the authors, this new information is “of vital relevance” for the management of the species.

Adams et al. examined the effects of El Niño on adult Chinook salmon as they migrate through the Gulf of the Farallones (PDF). Researchers found that the dressed weight of commercial landed Chinook was lower during El Niño compared to non-El Niño years, a reduction attributed to a disruption in the normal feeding cycle in the Gulf of the Farallones. The analysis suggests that management agencies need to give more consideration to ocean conditions as risk factors in planning the recovery of endangered and at-risk Chinook salmon spawning runs.

Green abalone (Haliotis fulgens; Philippi) (PDF) were once part of a large recreational and commercial fishery, but are now estimated to be at less than 1% of their baseline density. Past attempts at restocking wild populations using juvenile farm-raised green abalone have resulted in high mortality rates. In “Outplanting large adult green abalone (Haliotis fulgens) as a strategy for population restoration,” author Caruso explores the efficacy of using adult specimens—at least 10 years old—to augment wild populations. The resulting 40 percent survival rate is much higher than the survival rates of previous projects that used juveniles. Although it is costly to raise green abalone to adult size, it may be the best method, given the decades of past unsuccessful restocking attempts.

These articles provide information useful to fisheries managers and should be helpful for future recovery efforts.

Cover photo © Peter Hemming

The latest issue of California Fish and Game, 103-3, makes a significant contribution to the body of research related to longfin smelt in California. A paper titled, “Historic and contemporary distribution of Longfin Smelt (Spirinchus thaleichthys) along the California coast (PDF)” analyzes and presents observation data for this species from a variety of published and unpublished sources dating from 1889 to 2016. This anadromous fish, which is listed as threatened under the California Endangered Species Act, has been documented in a diverse range of habitats, including coastal lagoons, bays, estuaries, sloughs, tidal freshwater streams and nearshore habitats. In addition to providing a comprehensive look at the existing information available for longfin smelt along the California coast, this paper identifies additional information needed to improve management and enhance recovery of the species within the state.

In “Distribution and derivation of dabbling duck harvests in the Pacific Flyway (PDF),” the authors look at abundance, banding and harvest data from throughout the Pacific Flyway and other important source areas in the Central Flyway to estimate the distribution and derivation of Pacific Flyway dabbling duck harvests during 1966−2013. The Pacific Flyway has long been considered an important wintering area for dabbling ducks. Better knowledge of the origins of these birds could assist in both harvest and habitat management.

The authors of “Distribution of Amargosa River pupfish (Cyprinodon nevadensis amargosae) in Death Valley National Park, CA (PDF)” endured harsh environmental conditions to document the occurrence of Amargosa River pupfish along the lower Amargosa River drainage where the species has not been previously documented. The downstream-most location of Amargosa pupfish captured in this study extends the previously recorded geographic range approximately 49 river km. The findings not only determine the distribution of Amargosa River pupfish within Death Valley National Park, but will help identify suitable locations at which to establish long-term monitoring sites.

California Fish and Game has published high-quality, peer-reviewed science for the past 103 years, making important contributions to the understanding and conservation of California’s wildlife.

Cover photo courtesy of Gerald and Buff Corsi © California Academy of Sciences.