Science Spotlight

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  • August 29, 2018

Person holding large net with oiled duck on boat
Staff and volunteers of the Oiled Wildlife Care Network, managed by UC Davis, capture oiled wildlife using nets.

Laboratory with table covered in blue towel with oiled bird wrapped in towel held by man wearing white coveralls, white hat, glasses, and purple gloves. Woman also standing with mask, white coveralls, blue gloves, holding a clipboard and pen.
Staff of the Oiled Wildlife Care Network examine a bird collected from the Nov 7 2007 oil spill in San Francisco Bay.

Close up of person wearing purple gloves holding oiled cormorant with one hand on head and other hand on beak
Staff and volunteers of the Oiled Wildlife Care Network wash oil from a bird.

Young boy in yellow boots, black pants, red and gray jacket and man wearing blue jeans, blue jacket and glasses holding blue box tipped out toward water with bird looking out from box.
Staff and volunteers release rehabilitated wildlife.
 

Scientists from the California Department of Fish and Wildlife (CDFW) and University of California, Davis have published an opinion essay that advocates rehabilitation and release, rather than euthanization, of animals injured by oil spills. The essay, entitled “Life and Death: How Should We Respond to Oiled Wildlife?” can be found in the June 2018 issue of the Journal of Fish and Wildlife Management.

CDFW Environmental Scientist Laird Henkel and Dr. Michael Ziccardi, director of the Oiled Wildlife Care Network at the UC Davis School of Veterinary Medicine, argue that a coordinated effort to attempt rehabilitation of oiled wildlife is warranted on scientific, financial and ethical grounds.

Efforts to clean birds and mammals oiled by spills are not only publicly expected in California, but also mandated by laws enacted in the early 1990s. However, some critics have argued that rehabilitation is a waste of resources and that the most responsible action is to immediately euthanize impacted animals.

In their paper, Henkel and Ziccardi cite scientific studies that show oiled animals often survive just as well as non-oiled control animals, and that euthanasia should only be considered for animals unlikely to return to normal function after rehabilitation.

The scientists assert that the costs for wildlife rehabilitation are typically a very small portion of overall oil spill response costs. Costs are also typically independent of post-spill funds secured to restore impacted natural resources — the cost of cleaning wildlife does not reduce the post-spill restoration work.

From an ethical standpoint, Henkel and Ziccardi note that some people consider individual animals to have intrinsic value, and that as consumers of petroleum products, we have an obligation to reduce suffering and mitigate injuries from spills associated with the production, distribution, and use of petroleum products.

The scientists cite public safety and legal issues as additional rationale for rehabilitation. They contend that members of the public, untrained to care for animals, will attempt to help oiled animals on their own if professional organizations do not. They further assert that legislation protecting the environment is often catalyzed by public outrage over seeing oiled wildlife.

The essay can be found online at the link opens in new windowJournal of Fish and Wildlife Management website.

For more information on oiled wildlife rehabilitation in California, visit the link opens in new windowOiled Wildlife Care Network, or CDFW’s Office of Spill Prevention and Response.

All photos courtesy of University of California, Davis. Cover: One of many oiled ducks being soaped and treated.

Categories: General
  • August 16, 2018

Marten resting atop a broken tree truck covered in moss and lichens
Marten resting atop a broken tree truck covered in moss and lichens. © Photo by Marx Marquez of Green Diamond, all rights reserved.

Marten in tree viewed through spotting scope
Marten in tree viewed through spotting scope. © Photo by Marx Marquez of Green Diamond, all rights reserved.

Marten climbing down tree trunk with rodent in mouth
Marten climbing down tree trunk with rodent in mouth. © Photo courtesy of Green Diamond, all rights reserved.

A small population of a rare member of the weasel family has an improved chance at expanding its range, thanks to a joint effort between a forest products company and a state agency.

Green Diamond Resource Company recently signed a safe harbor agreement with the California Department of Fish and Wildlife (CDFW) to help assist in the recovery of the Humboldt marten. The agreement includes commitments by the company to create a 2,100 acre no-harvest reserve area for the marten, a 127,000 acre special management area for marten dispersal and monitoring, and dedicated funding and in-kind resources to support a possible assisted dispersal program and studies of how the martens use managed forests and adjacent public lands.

“We are looking forward to partnering with Green Diamond and exercising this relatively new safe harbor tool to facilitate and fund research and monitoring – and perhaps even help martens reconnect between the Six Rivers National Forest and the Redwood National and State parks,” explained CDFW Senior Environmental Scientist Jon Hendrix, who oversees the Timberland Conservation Program in CDFW’s northern coastal region.

Humboldt martens have been detected in the agreement’s no-harvest reserve area located on Green Diamond property and on the periphery of the company’s other lands covered by the agreement. The purpose of the agreement is to look ahead and voluntarily, proactively manage the land, in the hopes of increasing the presence of (and use by) a species that is protected by the California Endangered Species Act.

Humboldt martens were thought to be extinct in California until a small population was rediscovered in 1996 in portions of their historic range. Today, their known distribution in California is limited to areas of Humboldt, Del Norte and Siskiyou counties. In addition to the small population on Green Diamond property, Humboldt martens have also been detected on National Forest lands near tributaries of the Middle Fork of the Smith River.

In February 2016, the California Fish and Game Commission accepted a petition requesting the Humboldt marten be added to the list of threatened or endangered species under the California Endangered Species Act (CESA). CDFW has initiated a status review of the Humboldt marten which is nearing completion and presentation to the California Fish and Game Commission. During the candidacy review period, the Humboldt marten has been afforded all the legal protections provided under CESA.

In early 2016, Green Diamond applied for a California State Safe Harbor Agreement (California Fish and Game Code, sections 2089.2 – 2089.26) for Humboldt marten. The application included approximately 364,000 acres of Green Diamond’s timberlands, of which, approximately 137,000 acres fall within nine miles of the currently known Humboldt marten populations.

“Green Diamond has consistently applied a proactive view of forest stewardship and a science-based approach to managing its forests to the benefit of special status species such as northern spotted owls, salmon, steelhead and now, the Humboldt marten,” said Keith Hamm, Manager of Conservation Planning for the Green Diamond California Timberlands. “We embrace the opportunity to expand the marten population under this agreement and learn more about how marten use the company’s managed forests.” 

Although incidental take of Humboldt marten is authorized in the agreement, the goal is to conserve, protect, restore and enhance the martens’ habitat. Also included are specific measures to increase Humboldt marten populations and create new habitats.

The Safe Harbor Agreement itself is good for 40 years. It is structured to provide the opportunity for neighboring landowners to enroll their lands in the agreement and contribute to efforts to recover marten populations.

To learn more, please visit CDFW’s Timberland Conservation Program webpage, www.wildlife.ca.gov/Conservation/Timber.

More information about CDFW’s Safe Harbor Agreement Program Act can be found at, www.wildlife.ca.gov/Conservation/CESA/Safe-Harbor-Agreements.

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Top Photo: Collared marten in tree courtesy of Matt Delheimer. All other photos copyright of Green Diamond.  

Categories: General, Wildlife Research
  • August 8, 2018

Map of area around Los Padres National Forest, showing where the bear tilapia
This CDFW map shows the routes
and distances traveled by both bears
since being re-released in January.


A light brown bear with a black muzzle sits on a green tarp in the bed of a navy blue pickup truck.
The older bear, safely on her way
back to the wilderness after being
tranquilized in Montecito by a wildlife
officer on April 2. (CDFW photo)

We have an update on the two black bears that were burned in the Thomas Fire in late December/early January! Both bears were suffering from extensive burns to their paws when they were brought to CDFW’s Wildlife Investigations Lab in northern California. Under the care of CDFW Senior Wildlife Veterinarian Dr. Deana Clifford and Dr. Jamie Peyton of the UC Davis Veterinary Medical Teaching Hospital, the bears were given an unusual experimental treatment involving the use of sterilized tilapia skins as bandages. After the bears were well enough to survive on their own, they were returned to the Los Padres National Forest, as near as possible to where they were originally found. Both have covered many miles and each has been spotted at least once since their release.

The younger bear was seen in an avocado orchard on May 29 by a biological consultant conducting a bird nesting survey. The bear ran away, which is a good sign that she has not become habituated. The consultant was able to get photos and video of the bear, who appears to be in good physical shape.

The older bear, who was pregnant during treatment and at the time of her release in January, came down from the hills and wandered into the town of Montecito on April 2. A local wildlife officer tranquilized her and returned her to suitable habitat, and she’s stayed away from people ever since. Though she was reportedly in good general health, there has been no sign of a cub, so the pregnancy may not have been carried to term or the cub may not have survived.

GPS collars on the bears allow CDFW biologists to track the animals’ movements so they can see where each one has been. Data shows the younger bear usually stays near Fillmore, but has made the 10-mile trek back to her release site in the Sespe Wilderness Area at least three times. She also made a brief trip over to Highway 5, north of Castaic. The older bear spends most of her time in the hills above Ojai. “We are encouraged and so pleased that both bears have survived for eight months now after burn treatment and release – they have walked hundreds of miles on their treated feet by now,” Dr. Clifford said.

CDFW will continue to monitor the movements of both bears via their satellite collars for at least another year. The data will ultimately help scientists build their knowledge of how animals utilize landscapes affected by large fires.

Read the original story of the Tilapia Bears at: https://tinyurl.com/y849mru7

Top photo: The younger of the two bears, as seen in an avocado orchard on May 29. (Photo by Jessica West)

Categories: General
  • July 31, 2018

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:

  • link opens in new windowReproductive 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.
  • link opens in new windowComparison 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.
  • link opens in new windowField 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.

Categories: California Fish and Game Journal
  • July 24, 2018

Frog resting on rock
Yellow-Legged Frog

Small river pool of water featuring a small waterfall trees, rocks and steep, rocky terrain
Mountain Yellow-Legged Frog habitat

Many years of painstaking monitoring and assessment efforts undertaken by CDFW have helped guide an ongoing effort to bolster the dwindling populations of mountain yellow-legged frogs in Southern California.

Tim Hovey, a senior environmental scientist in CDFW’s South Coast Region, has been hiking through the forest to monitor and evaluate yellow-legged frogs in Little Rock Creek and Big Rock Creek in the Angeles National Forest since 2002, when they were listed under the Endangered Species Act (they were listed as state endangered in 2013). At that time, it was estimated that fewer than 100 adult frogs remained in the wild. 

The drastic decline of this population over the last 50 years has been a cause for concern to biologists. “The mountain yellow-legged frog is a critical part of the fragile stream ecosystem here in Southern California,” Hovey explains. “We hope that our efforts to increase the wild population through captive tadpole release will eventually lead to self-sustaining populations that will no longer require captive care to recover.”  

Hovey estimates that fewer than 400 adult mountain yellow-legged frogs currently exist in the wild in small populations throughout its range in Southern California. Threats to the species include habitat loss, pollution, non-native predators and the deadly amphibian disease chytridiomycosis, which is caused by the chytrid fungus. Some measures have already been taken to help the species. From 2002 to 2012, for example, CDFW was the lead agency involved in removing non-native predatory fish in a section of Little Rock Creek, located below the current mountain yellow-legged frog population, which essentially doubled the amount of high-quality habitat available for frogs in the stream.

But more human intervention is necessary, in the form of captive rearing. The multi-pronged effort to bolster mountain yellow-legged frogs includes contributions from the U.S. Fish and Wildlife Service, the Los Angeles Zoo, San Diego Zoo Global, the U.S. Forest Service, the U.S. Geological Survey (USGS), and others.

According to Hovey, the captive rearing project began in 2014, when wild-caught tadpoles were removed from Little Rock Creek and Big Rock Creek by USGS staff during a breeding cycle. The tadpoles were raised to adulthood in captivity at the Los Angeles Zoo in temperature-controlled aquaria in a quiet frog-rearing room, carefully equipped to mimic the frogs’ natural life cycle conditions.

While the tadpoles were growing, CDFW staff conducted field surveys to evaluate suitable habitat, using the data to identify specific streams where mountain yellow-legged frogs could potentially be released. The criteria for evaluation considered current recreational uses, access for monitoring, safety and property ownership. The resulting list of approved locations was reviewed by the other agencies and is being used to guide the releases.

On June 26, 500 tadpoles, descendants of the captive Big Rock Creek frogs, were released back into their historic range in the lower section of Big Rock Creek in the Angeles National Forest. Another 500 tadpoles, offspring of the Little Rock Creek captive group, were released on June 27 into Devils Canyon Creek in the Angeles National Forest. The offspring of the captive frogs, which were bred and kept separate, were released into their creeks of origin.  

“These releases represent a promising first step in the recovery of mountain yellow-legged frogs, as well as hopefully establishing new populations in areas where the frog has been absent for over fifty years,” Hovey said.  “We hope that with continued agency coordination and continued tadpole releases, the dwindling numbers of these endangered frogs will slowly begin to rebound and recover.”

This was the first release of tadpoles into Angeles National Forest with several more scheduled this summer throughout portions of the species’ range. 

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CDFW Photos courtesy of Tim Hovey. Top Photo: Mountain Yellow-Legged Frog.

For more information:

US Fish and Wildlife Service, “Trailblazing Tadpoles
US Fish and Wildlife Service, Draft Recovery Plan for the Mountain Yellow-Legged Frog
CDFW, Mountain Yellow-Legged Frog, description and taxonomy
 

Categories: General
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