Science Spotlight

Northern watersnakes are native to the eastern United States. A breeding population was discovered in Placer County in 2007 and a second population confirmed in 2014. Photo courtesy of Todd Pierson.


Coqui frogs have appeared periodically in Southern California. The first coqui was collected from a private residence in Orange County in 2012 and arrived on a tropical house plant.


Nutria have been confirmed in six central California counties, including Tuolumne County where this nutria was photographed near Don Pedro Reservoir in 2017. Photo courtesy of Peggy Sells.


Southern watersnakes are native to the southeastern United States and can reach lengths of 5 feet. They have been found in Yolo, Sacramento and Los Angeles counties. Photo courtesy of Todd Pierson.

Six months after announcing the discovery of a breeding population of invasive nutria in the San Joaquin Valley, CDFW’s Invasive Species “hotline” continues to receive multiple reports each week of nutria sightings from the public.

The reports come in on the toll-free line – (866) 440-9530 – or its e-mail counterpart – Invasives@wildlife.ca.gov – and numbers have reached as many as 30 e-mails and nine calls in a day.

The hotline accounts are checked each weekday – and often multiple times a day. CDFW attempts to respond to every individual submission. To date, about 95 percent of the nutria reports have turned out to be false – either sightings of other wildlife mistaken for nutria or reports that lack enough information to confirm one way or another.

“If it’s on your roof or chewing up the wires in your car, it’s not a nutria,” said Helen Benson, an environmental scientist with CDFW’s Invasive Species Program.

The misidentification of nutria is understandable. Nutria closely resemble several species of native and non-native wildlife, including muskrats, beavers, and rats, which adds to the challenge of a positive identification. Nutria are semi-aquatic rodents native to South America that haven’t been seen in California for 40 years until the spring of 2017 when a pregnant female turned up in a beaver trap.

Still, CDFW welcomes and encourages all reported sightings, preferably accompanied by a photo or video to help verify the identity.

In April, the hotline received one of its most important tips when an Animal Services officer with the City of Lathrop called to report catching and releasing a nutria – without realizing what it was at the time. The officer took photos of the animal, however, which became the second nutria confirmed in San Joaquin County on the edge of the Delta.&

CDFW has focused its early eradication efforts on keeping nutria out of the Delta, where their destructive burrowing into levees, ditches, canals and other water infrastructure could jeopardize the Delta’s flood control and water conveyance systems. CDFW has since launched nutria surveillance and eradication operations in the Delta to mirror those occurring farther south in the San Joaquin Valley.

While CDFW’s Benson estimates that about 80 percent of the Invasive Species hotline’s reports involve nutria these days, the hotline itself predates the nutria infestation by more than a decade. It was created in 2007 to help combat another invasive species crisis: the discovery of quagga and zebra mussels in California.

“Most people don’t realize that invasive species are the second-greatest threat to native species after habitat loss,” Benson said.

It’s easier to combat and possibly eliminate invasive species early before populations become entrenched, which explains CDFW’s aggressive nutria eradication response.

Coqui frogs are another invasive species dealt with quickly when reports come into the hotline. The voracious, tiny tree frogs native to Puerto Rico, Central and South America emit a deafening raucous that belies their small size. The call from one of these tiny amphibians can reach noise levels of 80 to 90 decibels – the same as a running lawnmower. Colonies of coqui frogs have been blamed for lowering property values on Hawaii’s Big Island.

Coqui frogs have turned up in Southern California, arriving in nursery plant shipments from Hawaii and other exotic locales. CDFW asks those contacting the hotline to record the frogs’ calls for confirmation, at which point CDFW will dispatch biologists to catch and remove the frogs.

The Invasive Species hotline has also proved helpful in combatting two invasive aquatic snakes that have turned up in Northern California – the northern watersnake and southern watersnake – likely released into the environment by disenchanted owners who acquired them as pets. Their ill temperament and unpleasant odor make them poor pets – along with the fact they are illegal to possess in California without a permit. CDFW has launched trapping efforts in the suburban Sacramento communities of Roseville and Folsom, where breeding populations of the snakes have been confirmed. It’s possible these snakes could find their way to backyard ponds and swimming pools, and reports to the hotline would help CDFW’s efforts to eradicate them.

Invasive species are a persistent threat to California, and the public plays an important role in helping CDFW identify and respond to new threats. Whether in their backyard or hiking their favorite trail, everyday citizens across the state are partners in protecting their natural resources by reporting unfamiliar plants and animals they don’t recognize.

CDFW Photos. Top Photo: Juvenile Coqui frog.

Veterinary staff assess deceased deer


Veterinary staff take samples of deceased cervid


Veterinary staff take samples of deceased cervid

CDFW scientists, wildlife officers and other staff are pulling out all the stops to fight a wildlife disease of major concern from crossing state lines and infecting native deer and elk populations.

Chronic Wasting Disease (CWD) is a contagious, always-fatal neurological disease that affects cervids (deer, elk and moose). In North America, the disease is currently found in captive and wild cervid populations in 24 U.S. states and two Canadian provinces. It has been detected in captive elk and sika deer in South Korea and free-ranging reindeer, moose, and red deer in Norway and Finland.

To date, a combination of legislation and geography have kept this disease at arm’s length from California, but the threat is still very real.

“All of us – scientists and wildlife managers, landowners and hunters – need to join forces and work together to keep this disease out of California, or the future could be disastrous for our native herds,” said CDFW Wildlife Veterinarian Brandon Munk, who participates in a multi-agency task force to fight CWD.

For California, this means two things: continuing to enforce strict cervid (animals and parts) importation and movement regulations, and ramping up disease surveillance efforts. This deer season, CDFW will be setting up voluntary check stations for deer hunters throughout California. Here trained staff will collect lymph nodes from the neck of harvested deer – a process that takes only minutes and is minimally invasive to the surrounding tissue. While waiting, hunters can get their tags validated and learn more about how to help prevent the introduction of CWD to California.

Once established, CWD is notoriously difficult to fight. The disease is spread by direct contact with infected animals or environments contaminated by the infectious agent called “prions.” Environmental contamination seems to play a very important role in the spread and maintenance of this disease. Once the environment is seeded with these prions, eradication is difficult – if not impossible – as prions are extremely difficult to remove from the environment or to disinfect. Prions can also remain infectious in the environment for years. Even controlled burning and freezing temperatures do not remove the threat. Most attempts to eradicate this disease have failed, and scientists in other states have had limited success in their efforts to control its spread.

CWD is also difficult to detect, in part because the outward signs often do not manifest until several years after initial infection. Currently, there is no effective live-animal test and there is no vaccine. Systematic testing of hunter-harvested deer is one of the most widely used surveillance methods available. Additionally, it is one important method to help ensure the disease has not entered the state and will help ensure CDFW can detect CWD early should it ever reach California. Early detection of CWD is the first and most important step to effective management of this disease.

CDFW has established a Chronic Wasting Disease Task Force to lead efforts preventing the spread of CWD to this state. Members include CDFW staff (biologists, veterinarians, communications officers and wardens), Fish and Game Commission employees and California Animal Health and Food Safety veterinarians. The task force is reaching out to the public and other local, state, and federal agencies to help with surveillance efforts, educating sportsmen about how they can do their part to prevent the spread of CWD and preparing a comprehensive management plan to allow for rapid response if the disease ever does make it to California.

“We are very lucky that to date, no California deer or elk has tested positive for CWD – but we’re not taking it for granted,” Munk said. “We urge hunters to educate themselves about this very real threat, and to do their part to make sure that we keep it out of California.”

CDFW has produced a short video on preventing the spread of CDFW, including a demonstration on antler removal and proper butchering techniques. You can also find background information, additional links and updates on California’s efforts to fight CWD at www.wildlife.ca.gov/CWD.

To find a CDFW check station to get your deer or elk checked, please visit www.wildlife.ca.gov/CWD or call (916) 358-2790.

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CDFW Photos. Top Photo: Veterinary staff takes and examines samples from deceased deer.

Staff and volunteers of the Oiled Wildlife Care Network, managed by UC Davis, capture oiled wildlife using nets.


Staff of the Oiled Wildlife Care Network examine a bird collected from the Nov 7 2007 oil spill in San Francisco Bay.


Staff and volunteers of the Oiled Wildlife Care Network wash oil from a bird.


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 Journal of Fish and Wildlife Management website.

For more information on oiled wildlife rehabilitation in California, visit the Oiled 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.

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. © Photo by Marx Marquez of Green Diamond, all rights reserved.


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.  

This CDFW map shows the routes
and distances traveled by both bears
since being re-released in January.


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)