Captive-breeding colony of Amargosa voles continues its success

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Captively bred Amargosa voles. Photo credit: Nora Allen

Since 2014, CDFW-WIL has partnered with UC Davis in order to create and maintain a breeding colony of Amargosa voles essential to the recovery of the species.  If interested in learning more about the history and progress of the colony, please read more here.  Below is a video showing a few of the vole pups bred in captivity (Credit: Janet Foley).

Restoring habitat for the endangered Amargosa vole

In the Spring of 2016, CDFW (WIL and Region 6), UC Davis, BLM, USFWS, and many volunteers partnered to restore a key habitat patch utilized by the Amargosa vole. This habitat patch used to sustain the highest density of Amargosa voles in the world, but in 2010 it began to deteriorate due to changes in hydrology. The Amargosa vole team worked diligently to restore the water supply and reinvigorate vegetation growth at the marsh. Learn more about the Amargosa vole project.

The Tule Elk, A California Comeback Story

By Tom Batter, WIL Scientific Aid

The elk (Cervus canadensis) to this day remains an icon of what once was the unsettled, untamed American frontier.  There are four extant subspecies of elk in North America.  The Manitoban elk (C.c. manitobensis) is exclusive to Canada, but the other three subspecies can be found in California.  They are the Roosevelt elk (C.c. roosevelti) of the north coast rainforests, Rocky Mountain elk (C.c. nelsoni) of the northeastern counties, and the tule elk (C.c. nannodes) native to the Central Valley.

Elk distribution in California.

Elk distribution in California.  Photo courtesy of the DFW Elk Management Program.

Tule elk look similar to other elk in general size, shape, and color (albeit tules wear a slightly lighter brown).  Generally speaking, however, tule elk are overcome in maximum size by both Rocky Mountain elk and the great Roosevelt elk.  A good sized Roosevelt bull, the largest of the subspecies, can reach 1,000 pounds or more.  Tule elk are the smallest subspecies; in fact, at one time they were colloquially referred to as ‘dwarf elk’.  A large bull tule elk will tip the scales at about 700-800 pounds (hardly a ‘dwarf’ by any means), yet under ideal conditions they may grow larger.

The tule elk, the smallest of the elk subspecies, are best adapted to open country and semi-desert conditions among elk races (McCullough 1969).  Image source: CDFW

Tule elk once roamed the San Jaoquin Valley in ample numbers.  Early settlers found tule elk roaming the foothills of the Sierra Nevada west to the central Pacific coast and from the headstream of the Sacramento River south to the Tehachapi Mountains.  Much like the affliction of the American bison on the Great Plains, tule elk became a casualty of human settlement — particularly after the Gold Rush.

Unregulated market hunting, competition with livestock, and the introduction of nonnative plant species all contributed to the decline of tule elk.  What was more devastating, however, was the conversion of elk habitat to agricultural land.  When settlers turned to the plow not only did it remove food and cover resources for elk, it also brought about direct conflict between elk and farmers.  Increasing crop and fence damage fueled campaigns for the removal of the tule elk by those individuals whose livelihoods were affected.  By the time elk hunting was banned by the state legislature in 1873, it was unknown if any tule elk even remained.

Luckily tule elk did remain, thanks in part to the protection provided by California cattle baron Henry Miller.  In 1874 a pair of Tule elk was discovered on the Miller and Lux Ranch by a local game warden at Button Willow.  Miller set aside 600 acres (near present day Tule Elk State Natural Reserve) to give the elk a chance to rebound.  In 1914, the elk had experienced such growth in numbers that Miller requested the California Fish & Game Commission work to relocate the elk from his ranch.

In order to relieve Miller from elk damage to his property and crops (reportedly estimated at $5,000 per year), the U.S. Biological Survey attempted to relocate tule elk by lassoing them from horseback and transporting them to new areas, with little success.  From 1914 to 1934 the California Academy of Science took on tule elk relocation activities 21 times over the next several decades.  These attempts were not very successful either, although they did contribute to establishing the herds at Owens Valley, Cache Creek, and the Tupman Reserve.

From 1971 through 1989 complete species protection was granted to tule elk.  State and Federal laws were passed to prohibit hunting of tule elk until a population of at least 2,000 was reached.  Habitat improvement programs combined with an aggressive reintroduction campaign by the Department of Fish & Game and other state and federal agencies yielded a significant increase in California’s tule elk population.

Tule elk of the San Luis National Wildlife Refugre, circa 1970s.  Image source: BLM 3rd Annual Report to Congress on The Tule Elk.

Tule elk of the San Luis National Wildlife Refuge, cca the 1970s. Image source: BLM 3rd Annual Report to Congress on The Tule Elk, March 1, 1979.

Today there are twenty-two tule elk herds in the Golden State, totaling around 4,200 individuals with the population trending upward.

Due to competing land use practices, it is not easy for tule elk to freely move between sub-populations; this requires the Department of Fish & Wildlife to take action in order to meet statewide management objectives.To help maintain healthy herds, every so often CDFW is tasked with capturing and relocating healthy elk to different established

Dr. Annette Roug (right, kneeling) leads a team of biologists as they attempt to weigh a cow elk.  Photo credit: Joe and Nancy Rodrguez.

Dr. Annette Roug (front right) leads a team of biologists as they attempt to weigh a cow elk. Photo credit: Joe and Nancy Rodrguez.

herds.  Removing elk from one herd and placing them in another helps to simulate the natural movement of individuals between herds which increases genetic diversity, an important function of a healthy population.

The Wildlife Investigations Lab took part in one such capture and relocation effort at the end of March.  A total of 36 elk were captured via helicopter from the San Luis National Wildlife Refuge near Los Banos.  Once elk were netted from the helicopter, they were processed by capture teams.  Capture teams took measurements, collected hair, blood, and other biological data to assess the health of the herd before they moved on to their new locations.

The animals were successfully released to join their new herds.  A portion of the captured animals were also radio-collared to collect post-release movement information.

An elk sets eyes on joining its new herd.  Photo courtesy of Joe and Nancy Rodriguez.

An elk sets sights on joining its new herd. Photo courtesy of Joe and Nancy Rodriguez.

To read the CDFW news release from this successful capture, click here.

For more information on the CDFW Elk Program, click here.

Interested in more tule elk biology?  Click here.

 

 

Wintertime in Vole Country

By Austin Roy – Scientific Aid

Amanda Poulsen, a graduate student from UC Davis and CDFW volunteer, with an Amargosa vole (Microtus californicus scirpensis) after recording demographic data and applying a numbered ear tag.

Amanda Poulsen, a graduate student from UC Davis and CDFW volunteer, with an Amargosa vole (Microtus californicus scirpensis) after recording demographic data and applying a numbered ear tag.

Winter is usually a time to cozy up in front of the fire with a cup of hot chocolate, but winter for the endangered Amargosa vole (Microtus californicus scirpensis) is a totally different story.  These elusive desert rodents do not hibernate like some other mammals.  They work during the cold winter nights (as low as 5F /-15C) and cool days in search of food.  Because of their yearlong activity, the work at WIL doesn’t slow down over winter either.

Researcher looking for predator tracks around known vole habitat near Tecopa, CA.

Greta Wengert Ph.D., a collaborator from the Integral Ecology Research Center, looks for predator tracks around known vole habitat near Tecopa, CA.

Little is known about Amargosa vole behavior and biology.  Most of the information available is derived from the Amargosa vole’s cousin, the California vole (Microtus californicus).  To remedy our lack of knowledge, a team of researchers and volunteers from WIL, UC Davis, and USGS continues to work through the winter to try to learn more about the Amargosa vole.

A track plate box used to record predator tracks

A track plate box used to record predator tracks

Our project involves monitoring the vole population by live-trapping the voles.  This trapping allows for us to assess the health of individual voles, record demographic data (age, sex, weight, etc.), give voles individually marked ear tags, and then release the animals back into their environment.  This type of research allows us to track changes in the population and get an understanding of the geographic range of the vole.  In addition to “hands-on” research, I am also involved with “hands-off” surveillance.  Non-invasive techniques such as looking for vole sign (feces and runways), water sampling, and recording vegetation allow me to gain information about the vole and its habitat while creating as little impact as possible.

A bobcat (Lynx rufus) captured on a trail camera near Tecopa, CA

A bobcat (Lynx rufus) captured on a trail camera near Tecopa, CA

Also, over the winter months I am continuing to gather data on the predators of the Amargosa vole.  Recent findings from USGS suggest that predation might be a limiting factor to the vole’s persistence in its environment.  In response to this finding I began a study to observe and document predators.  I am deploying trail cameras and once a month I conduct point counts to record predator species that utilize vole habitat.  With the help of volunteers, I am also collecting predator feces and pellets.  This allows us to examine the diet of predators and identify which predator species are eating the vole.

The Amargosa vole display recently installed in the Shoshone Museum, in Shoshone, CA.

The Amargosa vole display was recently installed by CDFW and UC Davis in the Shoshone Museum, in Shoshone, CA.

All of this information is well worth the discomfort of working through cold weather.  The data we collect is being applied to the management of the vole  and will aid researchers in understanding how to best help this imperiled animal.  For this reason, we happily bundle up, heat up some tea for our travel mugs, and embrace the weather as we continue to do our best to help the Amargosa vole survive in such an extreme environment.

UC Davis, CDFW and USFWS team up to assess western pond turtle health in California

The western pond turtle (Emys marmorata), the only native species of freshwater turtle in California, has been a species of special concern since 1994. Possible causes for declining western pond turtle populations include urbanization and habitat destruction (which often reduces or eliminates basking and nesting sites available near pond
habitat), poor water quality, and reduced survival of young turtles causing the population to be skewed towards aged turtles that don’t reproduce well.

The western pond turtle is California's only native aquatic turtle and a species of conservation concern. (Image courtesy of CDFW Outdoor California March-April 2011)

The western pond turtle is California’s only native aquatic turtle and a species of conservation concern. (Image courtesy of CDFW Outdoor California March-April 2011)

Another challenge to the survival California’s native western pond turtles has been the introduction and spread of non-native red-eared sliders (Trachemys scripta elegans).  Red-eared sliders were imported for the live food market and are popular in the pet industry, often resulting in illegal pet release. “Sliders” are larger than pond turtles
and outcompete pond turtles for nesting and basking sites.

This is a Red-eared Slider (Trachemys scripta), a common turtle in the pet trade. They compete in the wild with our native Western Pond Turtle, so they should never be released. (CDFW photo by Dave Feliz)

The Red-eared Slider is a common turtle in the pet trade. They compete in the wild with our native Western Pond Turtle, so they should never be released. (CDFW photo by Dave Feliz)

It is not known if disease is playing a role in the observed declines of western pond turtles.   Additionally, introductions of non-native red-eared sliders into pond turtle habitat might also introduce new pathogens (disease causing agents like viruses, bacteria, fungi, and parasites) or strains of pathogens that western pond turtles had not been previously exposed to.

Absolutely nothing was known about the pathogens western pond turtles are exposed to in California, so Janet Foley, Joy Worth and then Master’s student, Connie Silbernagel from UC Davis School of Veterinary Medicine, Deana Clifford from the CDFW Wildlife Investigations Lab, and Jamie Bettasco from the US Fish and Wildlife Service teamed up to conduct the first assessment of pathogen presence in western pond turtles across the state. The team also tested non-native red-eared sliders at study sites where both species were living  to see whether or not red-eared sliders carried different pathogens and whether or not western pond turtles living in the same sites as nonnative sliders were more likely to carry different pathogens.

A western pond turtle is being measured as part of a collaborative study to examine their health. (Photo courtesy of C. Silbernagel)

A western pond turtle is being measured as part of a collaborative study to examine their health. (Photo courtesy of C. Silbernagel)

The team found that both species of turtles carried Mycoplasma spp. bacteria (a cause of respiratory infections) with prevalence being highest at sites in southern California regions. Furthermore native western pond turtles that were infected with Mycoplasma spp bacteria were more likely to weigh less and live in southern California. All turtles tested negative for two common viruses, Herpesviruses and Ranaviruses, and Salmonella bacteria (which can cause gastroenteritis and is a bacteria that can infect people).

Dr. Connie Silbernagel tests the quality of a water sample. Connie earned her Master's degree at UC Davis conducting the western pond turtle health assessment with CDFW and USFWS.

Dr. Connie Silbernagel tests the quality of a water sample. Connie earned her Master’s degree at UC Davis conducting the western pond turtle health assessment with CDFW and USFWS.

This study is the first of its kind to document pathogen prevalence in both native western pond turtles and non-native red-eared sliders and will provide important baseline data as we strive to conserve western pond turtles in California.

Click here to view the abstract:

Silbernagel C, Clifford DL, Bettaso J, Worth S, Foley J. Prevalence of selected pathogens in western pond turtles and sympatric introduced red-eared sliders in California, USA. Diseases of Aquatic Organisms 107:37-47

Why is it important to report wildlife mortalities?

Over the past 12 months, the Wildlife Investigations Laboratory has been asking the public for their assistance in reporting wildlife mortality events.  WIL recognizes that mortality reports are an important tool in monitoring the health of the State’s wildlife. Wildlife mortality reports can:

  • help us better understand these phenomena;
  • lead to more effective prevention and control;
  • potentially detect emerging diseases affecting fish and wildlife; and
  • recognize problems that could affect human and domestic animal health.

WIL received 30 mortality reports submitted by the public from July 2012 – June 2013.  These reports documented mortalities in 21 different species and have been added to a permanent record so that we may potentially be able to detect phenomena such as seasonal mortality trends or weather mortality events in the future.

Mortality Reports:  July 2012 – June 2013

CDFW - WIL Wildlife Mortality Reports, 2012-2013

CDFW – WIL Wildlife Mortality Reports, 2012-2013

Public reporting makes a valuable contribution to the information we are trying to collect and is an important source for disease outbreak monitoring and emerging health threats. Please help us monitor the fish and wildlife populations in California.

For more information on wildlife mortality reporting, please follow the links below.

California wildlife mortality reports:

http://dfg.ca.gov/LivingWithWildlife/Mortality/

California roadkill tracking:

http://www.wildlifecrossing.net/california/

Wildlife heath information:

http://www.nwhc.usgs.gov/map/mortality_events.jsp

http://healthmap.org

www.wher.org

Growing Up Kit Fox

By Jaime Rudd, WIL Scientific Aid

Spring is a transformative season in California’s Colorado Desert. The mild weather and gentle rains that trickle down during this time of year are what entices the desert flora and fauna to awaken from their dormancy.

California's Colorado Desert. This desert is a subdivision of the larger Sonoran Desert that encompasses Arizona, southeastern California, most of the Baja California peninsula, the islands of the Gulf of California, and much of the state of Sonora, Mexico. Map image courtesy of http://www.grabovrat.com.

California’s Colorado Desert. This desert is a subdivision of the larger Sonoran Desert that encompasses Arizona, southeastern California, most of the Baja California peninsula, the islands of the Gulf of California, and much of the state of Sonora, Mexico. Map image courtesy of http://www.grabovrat.com. Inset photo courtesy of Jaime Rudd.

Colorful desert flowers come into bloom and sweeten the air as moths, butterflies, bees and other insects bustle about collecting pollen all the while fertilizing each blossom.  Various desert reptiles come out from torpor and sprawl upon the sand as the sun’s rays rest upon their backs.  The invertebrates and small mammals, when not offering new life of their own, are out collecting seeds and eating the newly arrived vegetation. It is also the time of year when the mild-mannered spring desert welcomes the next generation of desert kit foxes (Vulpes macrotis).

A mated pair of desert kit foxes. The male (top photo), stretches after a night of hunting for both his mate (bottom photo) and himself. These foxes both serve as disease sentinels in the California Department of Fish & Wildlife's (CDFW) desert kit fox disease monitoring project. Each fox is equipped with a radio collar that emits a unique frequency allowing biologists to monitor their survival after an outbreak of canine distemper virus (CDV) occurred in this desert valley the year before.

A mated pair of desert kit foxes. The male (top photo), stretches after a night of hunting for both his mate (bottom photo) and himself. These foxes both serve as disease sentinels in the California Department of Fish & Wildlife’s (CDFW) desert kit fox disease monitoring project. Each fox is equipped with a radio collar that emits a unique frequency allowing biologists to monitor their survival after an outbreak of canine distemper virus (CDV) occurred in this desert valley the year before. Photo courtesy of CDFW, Region 6.

Monogamous in nature, kit foxes form pair-bonds that can be lifelong. During the early stage of pup-rearing and care, the female will hermit herself inside the den. Her mate is busier than usual, setting out to hunt for two, returning to the den with prey.

This female desert kit fox keeps a close eye on her den. She has 4 pups that her and her mate have been diligently been providing for.

This female desert kit fox keeps a close eye on her den. She has 4 pups that her and her mate have been diligently been providing for. Photo courtesy of CDFW, Region 6.

Once the pups are old enough, they are coaxed from their subterranean shelter under the watchful eye of their parents.

Already a couple of months old, the pups begin to explore a bit more while their parents remain close by.

Already a couple of months old, the pups begin to explore a bit more while their parents remain close by. Photo courtesy of CDFW, Region 6.

At nearly 3 months old, these pups are gaining more independence. While neither parent is seen in the photograph, they remain nearby.

At nearly 3 months old, these pups are gaining more independence. While neither parent is seen in the photograph, they remain nearby. Photo courtesy of CDFW, Region 6.

The pups will continue to stay with their parents for the duration of spring and early summer. The later summer months bring with it heat, independence, and all too often difficult life lessons. It is in these later months that the journey into adulthood and harsh desert introductions may end for some.

Remote cameras captured these images of a bobcat (Lynx rufus, top photo) and a coyote (Canis latrans, bottom photo) passing through a desert kit fox den complex.

Remote cameras captured these images of a bobcat (Lynx rufus, top photo) and a coyote (Canis latrans, bottom photo) passing through a desert kit fox den complex. Photo courtesy of CDFW, Region 6.

But for now, the season is young and it is still a time when the desert truly gives life, both day and night.

This male desert kit fox looks over his 4 pups on a cool desert evening. Sunset is one of the most active times for desert kit foxes as the adults prepare to leave their den complexes (and their young) for an evening hunt.

This male desert kit fox looks over his 4 pups on a cool desert evening. Sunset is one of the most active times for desert kit foxes as the adults prepare to leave their den complexes (and their young) for an evening hunt. Photo courtesy of CDFW, Region 6.

The Wildlife Investigations Laboratory would like to thank Jose Figueroa & David Elms from our Region 6 CDFW office for the wonderful photos captured by remote camera. Remote cameras have been a useful, non-invasive tool for biologists to detect animal presence and monitor the health and physical condition of these desert dwellers. All the photos featured in this story belong to a single mated pair that is being monitored as part of CDFW’s desert kit fox disease monitoring efforts in Riverside County.