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

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Disease Surveillance Projects for Bighorn Sheep Completed in November

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Dr. Colleen Duncan from Colorado State University and Dr. Ben Gonzales from California Department of Fish and Wildlife collect biological samples from bighorn sheep for disease testing. (Photo courtesy of George Kerr, Society for the Conservation of Bighorn Sheep)

Early November 2013 was a busy time for Wildlife Investigations Laboratory staff.  Two important disease surveillance projects for bighorn sheep were conducted in the Mojave National Preserve in San Bernardino County and the Peninsular Ranges in San Diego and Imperial Counties.  A total of 91 sheep were captured, GPS collared for monitoring and biological samples taken so that a variety of disease tests could be done.  One significant test is for Mycoplasma ovipnenumonia, a bacteria that caused a bighorn die-off in the Mojave earlier this year. Scientists will use the laboratory results (still pending) to determine the cause of the disease and to document the number of animals involved and the geographic extent of the outbreak.

These projects could not have been conducted without the many partners involved including; The National Park Service, the Society for the Conservation of Bighorn Sheep, California Wild Sheep Foundation, United States Fish and Wildlife Service, Bureau of Land Management, Oregon State University and Colorado State University.

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Taking blood samples from bighorn sheep for use in disease testing. (Photo courtesy of George Kerr, Society for the Conservation of Bighorn Sheep)

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Inspecting bighorn for signs of respiratory distress. (Photo courtesy of George Kerr, Society for the Conservation of Bighorn Sheep)

Golden eagles with mange

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Photo of golden eagle with mange. Courtesy of K. Shawn Smallwood.

The Wildlife Investigations Lab has been involved in the investigation of three cases of severe mite infestation, or mange, affecting subadult golden eagles in central California. Two cases were reported to WIL by SPCA for Monterey County in December 2012 and August 2013, while a third case was reported by biologists with the East Bay Regional Park District, also in August 2013. The eagles had significant feather loss and crusting of the skin on their head, neck, legs, and lower abdomen.

Severe mite infestation is unusual in birds and especially uncommon in adult birds. The degree of feather loss and infestation exhibited by these golden eagles has not been previously documented. Mange likely affects the eagle’s ability to maintain normal body temperature and they may have difficulty obtaining food, becoming weakened, possibly increasing their susceptibility to trauma or other disease.We are currently working with researchers from the East Bay Regional Park District, SPCA for Monterey County, and the University of California, Davis to thoroughly document these cases, identify the mite, and evaluate any underlying health conditions.

The public is urged to notify the California Department of Fish and Wildlife if additional golden eagles, or other raptors, are seen with severe feather loss. If you find a live-eagle on the ground, do not attempt to capture the bird yourself, as these birds can be extremely dangerous; rather, please contact your local licensed wildlife rehabilitation center for assistance.

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Photos of featherloss on head and legs of golden eagle with mange. Courtesy of Amy Wells (head photo) and Krysta Rogers (leg photo).