Throwback Thursday: An Unusual Sea Otter Study

By Tom Batter, WIL Scientific Aid

Happy Throwback Thursday loyal readers!  Today we highlight an article describing an experimental approach by DFG to help curb losses to the abalone industry.  The experiment called for DFG to partner with commercial fisherman to supplement feed to the sea otter populations off the coasts of Monterey and San Luis Obispo counties.  The goal in mind was to make the sea otter’s southern migration unnecessary to help boost abalone production.  Quite an interesting approach that, to this author’s knowledge, was ineffective.  This excerpted page originally appeared in the 1967 November-December issue of Outdoor California.

NovDec67

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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.

New publication describes the cause of a skin disease in endangered Amargosa voles

In only 19 square kilometers of the Amargosa basin in the Mojave Desert of California, lives the small, brown Amargosa vole (Microtus californicus scirpensis). This specialized vole lives in bullrush (Scirpus oleyni) dominated marshes that appear when the normally underground Amargosa river reaches the surface.  Conservation of this unique habitat on which this state- and federally-listed endangered vole depends has been a cornerstone of conservation efforts.

Image

A sunset view of one of the unique marshes that provide critical habitat for the endangered Amargosa vole. (Photo by D. Clifford)

While conducting surveys to determine for Amargosa Voles in September 2010, California Department of Fish and Wildlife scientist Tammy Branston discovered unusual deformities on the ears and genitalia of some of the voles which appeared to be associated with the presence of an orange substance on the skin.  Some voles were so severely affected that they were missing their ear pinnae (the visible part of the ear) altogether. Tammy alerted CDFW veterinarian Dr. Deana Clifford, and along with her colleagues Dr. Janet Foley, a small mammal disease ecologist at UC Davis, and Dr. Leslie Woods, a veterinary pathologist at the California Animal Health and Food Safety Lab (CAHFS) at UC Davis, they sampled affected voles and conducted additional tests to determine the cause of the deformities.  They discovered that the orange “stuff” was actually a hard orange mite, a chigger in fact.   Of 151 Amargosa voles examined from February-April of 2011, 40% of the voles had hard orange mites adhered to some part of their bodies, and 47% of voles examined had ear lesions and deformities which included alopecia (hair loss), swelling, tissue death and ulcers at the ear edges, as well as scarring, scabbing, and loss of external ear tissue.

The team’s findings are published in the August 2013 issue of the Journal of Parasitology.

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An Amargosa vole with a normal ear is ready to return to the bulrush after its examination. (Photo by D. Clifford)

It is extremely unusual to see such severe damage due to a chigger in a small mammal, which raises concerns that this condition could negatively impact the health and fitness of individual voles.

An interdisciplinary team with members from CDFW, UC Davis, UC Berkeley, the Bureau of Land Management, the US Geological Survey, and the US Fish and Wildlife Service, is studying population dynamics, habitat needs, genetics, and disease in order to ensure that healthy populations of this unique endangered vole of the desert persist well into the future.

To access the paper abstract, click here

Full reference: 2013. Foley J, Branston T, Woods L, Clifford D. Severe ulceronecrotic dermatitis associated with mite infestation in the critically endangered Amargosa vole (Microtus californicus scirpensis). Journal of Parasitology.  Aug;99(4):595-8.

Click here to read more about the Amargosa vole and download recovery documents.

Click here to read about agency efforts to enhance the voles habitat, the Amargosa Area of Critical Environmental Concern (ACEC).

Click here to learn more about the Amargosa Conservancy’s local efforts to protect the Amargosa Basin.

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

California to Host Desert Bighorn Council Meeting in 2015

Desert bighorn ewe and lamb

Desert bighorn ewe and lamb
photo by T. Glenner

California will be the host of the 2015 Desert Bighorn Council Meeting. The meeting will take place in Borrego Springs, California in April 2015.  This biennial meeting brings together wildlife biologists, scientists, administrators, managers, and others interested in the welfare of desert bighorn from the seven western states (Texas, New Mexico, Colorado, Arizona, Nevada, Utah and California) to exchange information, present research and take action on matters pertaining to desert bighorn management.

The Council Chair for the 2015 meeting is Dr. Ben Gonzales, Senior Wildlife Veterinarian at the Wildlife Investigations Lab. The Program Chair is Steve Torres, Environmental Program Manager at the Wildlife Investigations Lab. Mark Jorgensen, former Superintendent of Anza Borrego Desert State Park will serve as Local Arrangements Chair.

For more information of the Desert Bighorn Council, please see:

http://www.desertbighorncouncil.org/about.html

Fisher Translocation Project Completes Successful Trapping Effort

by Deana Clifford, wildlife veterinarian

Here’s a post and a photo slide show from our colleagues working on  the Fisher Translocation Project. In this post, Kevin Smith describes our successful efforts to capture, examine and monitor fishers.

The Fisher Translocation Project is led by the CA Dept of Fish and Game (CDFG), the US Fish and Wildlife Service (USFWS), North Carolina State University, and Sierra Pacific Industries. The goal is to translocate fishers into a portion of their historical range in the northern Sierra Nevada. If successful, this project will provide significant benefits to the conservation of fishers in the state.

Photo of DFG Biologist releasing fisher into wild.

CDFG lead for the translocation, Richard Callas and biologist,  Scott Hill release a fisher into the northern Sierras.

Over the past 3 years we have translocated 40 fishers from Northern California to the Stirling Management Area in the northern Sierra Nevada. Although it will take many years to determine if a permanent population will become established, early findings indicate that translocated fishers are successfully reproducing and that fishers born in Stirling are healthy.

The WIL nongame health program provides support to this project by conducting examinations, supervising immobilizations and training field crews. Along with our partners at the Integral Ecology Research Center, and the California Animal Health and Food Safety Lab, CDFG is monitoring the health of these fishers during and after release by determining the cause of any mortalities and conducting testing to determine what diseases fishers and other carnivores are exposed to.

See more information about this project.

A Historical Review of Sierra Nevada Bighorn and the Road to Recovery

By Tom Batter, Wildlife Investigations Lab Scientific Aid

“Bighorn… are extremely wary and cautious animals…His strength and his self-reliance seem to fit him above all other kinds of game to battle with the elements and with his brute foes; he does not care to have the rough ways of his life made smooth; were his choice free his abode would still be the vast and lonely wilderness in which he is found.”

Theodore Roosevelt, Ch. VII A Trip After Mountain Sheep, Hunting Trips of a Ranchman (1885)

While the future President Roosevelt was referencing bighorn sheep (Ovis canadensis) of the North Dakota badlands, his description can be applied just as aptly to the Sierra Nevada bighorn (O. c. sierrae) of California’s east-central boundary.  The rugged mountain peaks and canyons combined with semi-open forest areas provide ideal habitat for these bighorn.

An alert group of Sierra Nevada bighorn.
Image courtesy of John Wehausen & the US Fish & Wildlife Service

Sierra Nevada bighorn sheep (SNBS) are an endangered genetically distinct subspecies of bighorn. They are only found in the mountain range that provides their common name.  Today, these sheep are on the road to recovery, in part thanks to intense monitoring by the Department of Fish and Game’s Sierra Nevada Bighorn Sheep Program (SNBSP) in conjunction with the Sierra Nevada Bighorn Sheep Foundation.  Led by Dr. Tom Stephenson, the program’s goal is to recover sheep numbers to the point that downlisting, or the ultimate goal, delisting, would be warranted.

Recovery activities center around understanding and managing factors that influence population health and the distribution of these bighorn. Among the factors that could be limiting Sierra Nevada bighorn numbers are disease from domestic sheep, predation, weather events and forest succession, which may limit habitat.

Indeed, the preferred haunt of the bighorn is open habitat adjacent to steep and rocky ground.  They are behaviorally and morphologically suited for such an environment.  Bighorn are equipped with keen binocular vision to detect predators from a great distance. Their short legs, hefty frames and low center of gravity provide agility and tremendous balance.  Their hooves are hard on the outer edges and spongy at the center, a unique adaptation that facilitates exceptional grip on rock.  When danger is perceived, the sheep make the most of their physical abilities by retreating into the nearby cliffs and rock walls where few predators can pursue them.

A home fit for a sheep.
(Photo credit T. Batter)

While it is true bighorn are first-rate predator evaders, they have historically had a harder time avoiding another serious threat: humans.

It was during the mid-1800s that Sierra bighorn sheep numbers began to decline.  Throughout this time California experienced a population boom due to the discovery of gold.  Once the gold rush craze eased up, settlers that remained in the area turned to ranching.  Domestic sheep and cattle began grazing the Sierras, increasing forage competition.  At the beginning of the 20th century, bighorn numbers were down to the thousands.

Domestic sheep graze in the Sierras.
Image courtesy of USDA-Forest Service

Grazing sheep and cattle on western federal lands became the subject of a sizzling congressional debate.  President Roosevelt was neither a fan of forest grazing nor of domestic sheep themselves – he described them as “the most foolish of all tame animals” and referred to flocks as “fleecy idiots.”  A quarrel over sheep grazing created a rift between legendary conservationists John Muir and Gifford Pinchot.  Pinchot assured Muir he was against sheep grazing in forest reserves.  Muir furiously confronted Pinchot over quotes in a Seattle newspaper that suggested otherwise. Disagreement between wool growers and preservationists was high, which ultimately led to grazing regulations and agreements.

While forage competition and over-hunting played a role in bighorn population decline, today one of the most critical threats to Sierra Nevada bighorn recovery is disease transmission from domestic sheep .  Domestic sheep are carriers of pathogens that cause respiratory disease in wild sheep.  While domestic sheep remain unaffected, bighorn that are exposed have no defense against these pathogens and are therefore extremely susceptible to disease and ultimately death.

Recent pneumonia related all-age mortality events have resulted in the deaths of hundreds of bighorn in the Rocky Mountain West. Research implicates a particularly difficult-to-diagnose bacteria,  Mycoplasma ovipneumoniae, in initiating many of these outbreaks.  While Mycoplasma ovipneumoniae is commonly found in healthy domestic sheep, years of extensive testing has demonstrated that this bacteria is absent from Sierra Nevada bighorn herds.  This absence certainly results in healthy bighorn, but it also means that the wild herds will be very susceptible to respiratory disease if they are exposed to the organism.  Once exposed, the typical sheep habit of nose-to-nose greetings can result in the unstoppable transmission of the organism within the herd.  Extensive ram movements can then spread the disease to other populations.  Historically, these disease outbreaks have resulted in initial all-age mortality followed by years of high lamb mortality, both of which will delay or prevent the recovery of the Sierra Nevada bighorn sheep.

By the mid-1990s, an estimated 100 bighorn remained in the Sierra Nevada region.  Such low numbers expedited the process of listing the sheep as endangered; in 2000, the Sierra Nevada bighorn sheep became the first federally endangered species listed in the 21st century.

Bighorn sheep have heavy ridges which run across the horns, formed each winter. It is possible to age a sheep based on the number of deep grooves. This ram I am supporting was about 7 years old and weighed in near 240 lbs! (Photo credit T. Batter)

This is where Dr. Tom Stephenson, SNBS program personnel, and the Wildlife Investigations Lab (WIL) enter the equation.  Once every fall and spring, Sierra Nevada bighorn are captured and fitted with radio and GPS collars.  Sheep are captured from a helicopter using a hand held net gun (services rendered by Leading Edge Aviation).  The captured sheep are hobbled, blindfolded, and securely fastened into a carrier.  The sheep are then airlifted to a base camp and monitored by processing teams where their safety is the top priority.  In base camp, WIL provides essential equipment, expertise and training in wildlife restraint and humane care, as well as veterinary medical care of injuries or medical problems that occur during the capture

WIL veterinarian Dr. Ben Gonzales lends his expertise in monitoring the health of each sheep that is flown in.  Crew members are trained to closely monitor the bighorn and to collect appropriate blood and nasal samples to evaluate population health.  After the team fits the collars and applies an ear tag, the bighorn is then airlifted back to the capture site where it rejoins the flock.  The collared sheep will then begin to accumulate data that is imperative to their recovery success.

The radio and GPS collars are very useful and important tools in the recovery process for these animals.  Movement patterns, habitat use, survival and causes of mortality can all be examined.

Radio and GPS collars are securely fastened on a ram.
(Photo credit T. Batter)

Furthermore, human recreational impact on the bighorns can be assessed, as well as the grazing overlap between bighorn and domestic sheep.  The collected data will allow for science-based management decisions to be made in order to ensure the survival of Sierra Nevada bighorn.  So far, efforts have helped increase Sierra Nevada bighorn numbers to over 400 individuals.

The Leading Edge Aviation crew as they airlift two processed sheep back to their flock. (Photo credit Trista Welsh)

President Roosevelt went on to describe bighorn sheep as having “…no animal in the world his superior in climbing…”  With successful recovery efforts, the SNBS Program and the Sierra Nevada Bighorn Sheep Foundation in partnership with the Wildlife Investigations Laboratory will help guarantee that these rare bighorns remain the ultimate mountain climbers well into the future.

SNBS ewe is collared, tagged, and ready to return! (Photo credit T. Welsh)