On Thursday, August 9, 2018, the CDFW Wildlife Investigations Laboratory sampled and processed over 350 bats that had been submitted by the California Department of Public Health; all bats had been found dead throughout the State and subsequently tested negative for rabies. Assisting with the sampling and processing were representatives from the Museum of Vertebrate Zoology located in Berkeley, CA. Processing involved determining the species of each bat, collecting morphometrics, screening the bats for white-nose syndrome (WNS) under ultraviolet light, and collecting biological samples. In addition to gaining knowledge of species distribution throughout the State, the bats will provide opportunities for stable isotope research, genetic analysis, wind farm mortality studies, and growth of museum collections. Furthermore, the processing provides valuable disease surveillance data with regards to WNS, a disease that is decimating bat populations throughout the United States. For more on WNS, please visit:
The Wildlife Investigations Laboratory is working with biologists and wardens throughout California to ramp up Chronic Wasting Disease (CWD) surveillance of deer. CWD is a fatal neurologic disease of deer and elk that has been detected in 25 states, 2 Canadian provinces, South Korea, Norway, and Finland. The disease has never been detected in California, but the best defense is a robust surveillance program, and an informed public. In 2017 effort was focused on collecting samples from hunter-harvested animals in the X-zones along California’s border. In total 100 animals were tested for CWD, and all came back negative. This year CDFW plans to expand surveillance throughout the state. Keep an eye on our CWD page for more information about CWD sampling locations during the 2018 hunt season. If you are planning to hunt out of state this year, be sure to follow the law, NO SKULL or BACKBONE. We also recommend to hunters who take a deer or elk in a CWD positive state to get your animal tested and processed in that state, and not to consume the meat until you have a negative test result.
Click here to view the brochure on CWD.
Andrew Di Salvo, DVM, the inaugural Free-Ranging Wildlife Health Veterinary Resident with the CDFW Wildlife Investigations Laboratory and the UC Davis Karen C. Drayer Wildlife Health Center, shares a photo from each month of his first year…
An understanding of the demography, distribution, behavior, and genetic diversity of animal populations enables the California Department of Fish & Wildlife to properly manage species statewide. Capturing bighorn sheep provides an opportunity to place GPS and VHF collars, as well as collect biological samples (e.g. blood, nasal swabs, hair, feces). This accumulation of data will offer insight into bighorn sheep population dynamics, genetic diversity, and overall health.
From October through November of this year, CDFW participated in helicopter captures of multiple bighorn sheep populations. After ensnaring the sheep in a net, a capture crew member would exit the helicopter, secure the sheep by placing leg hobbles and an eye cover, and then either process the sheep in the field or place it in a carry bag for long-line transport to a base camp for processing. Processing at the base camp consisted of weighing the sheep, collecting morphometrics (body measurements), blood, hair, feces, and nasal swabs (for detection of Mycoplasma ovipneumoniae, a bacteria that can cause a fatal pneumonia), administering vitamin E and selenium injections, followed by GPS and/or VHF collar placement and ear tagging. Additionally, an ultrasound examination was performed to both determine body condition score by measuring the thickness of subcutaneous fat and particular muscle bodies, as well as check if any ewes were pregnant. Following processing, sheep were either released from the base camp or returned by helicopter to the capture site for release.
Up first on the schedule were the endangered Sierra Nevada bighorn sheep. Over the course of six days in the Sierra Nevada Mountains, a total of 34 sheep were captured, including seven rams, with 33 sheep receiving at least one VHF or GPS collar (33 VHF, 31 GPS). Operations then moved to the Sespe Wilderness Area within Los Padres National Forest to capture desert bighorn sheep that had originally been translocated to the area, part of their historic range, back in the mid-1980s. This was quite the unique opportunity in that these sheep were thought to be all but gone from the range in the early 2000s and were only recently seen on the landscape. Furthermore, the population hadn’t been handled in the more than 30 years since their initial reintroduction. A total of 22 sheep were captured over three days, including 10 rams, with 19 sheep receiving at least one VHF or GPS collar (15 VHF, 13 GPS). The Sespe captures were followed by four days in Anza Borrego State Park and Palm Desert, CA for field processing of desert bighorn sheep from the Peninsular Ranges. These efforts yielded 42 total captures, all ewes, with each sheep receiving at least one VHF or GPS collar (18 VHF, 26 GPS). The capture team then moved to the Mojave Desert and Death Valley National Park for seven days of desert bighorn sheep processing, yielding 71 total captures, including 18 rams, with all but two sheep receiving both a VHF and GPS collar (69 VHF, 69 GPS). Capture operations wrapped up in the White Mountains just outside of Bishop, CA, where 33 desert bighorn sheep were captured over four days, including 12 rams, with all but two sheep receiving both a VHF and GPS collar (31 VHF, 31 GPS).
In less than one month, CDFW captured 202 bighorn sheep, placed 166 VHF and 170 GPS collars, and collected abundant biological samples that will be closely studied for the next few years. The information acquired through analysis of the biological samples, as well as the continual spatial data that the collars will generate, will provide CDFW with valuable material by which they can make educated and well-informed decisions regarding the management of the state’s bighorn sheep populations.
Recent work from Amanda Poulsen (UC Davis) in partnership with researchers at CDFW-WIL has been published in the Journal of Wildlife Diseases. This work examined the prevalence and potential impacts of toxoplasmosis in the wild Amargosa vole population. To access the paper abstract, click here.
Full reference: Amanda Poulsen, Heather Fritz, Deana L. Clifford, Patricia Conrad, Austin Roy, Elle Glueckert, and Janet Foley (2016) Prevalence and Potential Impact of Toxoplasma gondii on the Endangered Amargosa Vole (Microtus californicus scirpensis), California, USA. Journal of Wildlife Diseases In-Press.
Be on the look out for band-tailed pigeons! Reports this month indicate band-tailed pigeons, California’s only native pigeon, are utilizing areas where they haven’t been in years. Observers have reported flocks of 50 to 100 birds in locations where pigeons haven’t been seen in at least 15 to 20 years. These seemingly erratic movements are directly tied to available food resources. During the winter, band-tailed pigeons feed primarily on acorns. They are one of the few species that actually swallow acorns whole!
Acorn productivity fluctuates among oak species and between years. In some years, oaks may produce large quantities of acorns, in other years acorn production can be spotty. If acorns are not available, pigeons will rely on other food items such as madrone berries or pine nuts. However, the availability of all these plant foods are dependent upon weather conditions including temperature and the timing of rain, which leads to changeable food resources. Band-tailed pigeons must be adaptable to these variable conditions and seek out food resources across the landscape.
The observations of pigeons using “non-traditional” locations this winter may possibly be influenced by recent drought conditions. In Sacramento County, acorn productivity this season was very high and, in fact, bird watchers reported seeing flocks of band-tailed pigeons along the American River during fall migration. In contrast, a recent trip to the Los Padres National Forest in Monterey County, a location known to be especially reliable for both acorns and band-tailed pigeons, revealed neither acorns nor band-tailed pigeons this winter! Instead, pigeons were observed at lower elevations where abundant food was available.
Also likely related to drought, was the increased incidence of Trichomonosis in band-tailed pigeons this summer. Trichomonosis is a disease caused by a single-celled microscopic protozoan parasite, Trichomonas gallinae. The parasite lives in the mouth and throat of infected birds, causing caseous (“cheese-like”) lesions to develop in the birds’ mouth or esophagus. The lesions eventually block the passage of food, causing the bird to become weak and emaciated. Infected birds die from starvation, or suffocation if the lesions block the airway.
Band-tailed pigeons are highly susceptible to infection with Trichomonas gallinae. Traditionally, large-scale die-offs occur during the winter months, in some years. However, this year the Wildlife Investigations Lab received reports of increased mortality of band-tailed pigeons in several locations along the central California coast between May and August. Drought conditions likely resulted in increased contact between individual birds at limited food or watering sites, resulting in rapid spread of disease. This increased mortality of band-tailed pigeons is concerning because the band-tailed pigeon population has been declining for the past 40 years. Die-offs due to Trichomonosis can remove hundreds to thousands of pigeons from the population in a relatively short period of time.
This winter, be on the look out for band-tailed pigeons in your area. If you see pigeons, enjoy the spectacle, it may not occur at that location for another 20 years! And if you happen to observe pigeons that appear sick, such as showing signs of weakness, labored breathing, breathing with their bill open, drooling, reluctance to fly when approached, or are dead, you can help by reporting the mortality to the Wildlife Investigations Lab.
If you have any questions, or would like to report sick or dead band-tailed pigeons, contact Krysta Rogers at 916-358-1662.
By Austin Roy (Scientific Aid)
Reintroductions, translocations, and augmentations are methods of restoring or increasing wildlife populations. These actions require a lot of planning and are often expensive. These methods involve removing animals from a source population and placing them in another location. The goal of these efforts are usually to establish a sustainable population where one did not previously exist, provide new individuals to a site with a low population in hopes of increasing the population, and providing new or rare genes to a population that may need genetic rescue, among other reasons.
This summer our University of California, Davis and California Department of Fish & Wildlife (WIL) research team conducted a population augmentation for the endangered Amargosa vole (Microtus californicus scirpensis). Our goal was to supplement a very small population of voles in one marsh with new individuals and genes from a larger population in another marsh.
We placed radio collars on 3 voles at the source site, 4 voles that we removed from the source site and relocated to the recipient site, and 3 individuals at the recipient site. By collaring both relocated voles and resident voles at source site and the recipient site we could monitor how relocated animals utilized the new site and whether or not resident individuals were impacted by the presence of new individuals in their habitat.
The data we collected will greatly benefit vole recovery and inform how we conduct future releases.
In addition to the augmentation efforts this summer we also continued to study the population cycles of voles and predators in the area. These studies allow us to better understand how voles and predators use the area how the predators may be affecting vole populations. We have also been studying the vegetation and water levels to better understand the needs of the Amargosa vole. These efforts will help us better understand how to restore and improve vole habitat.
The research this summer would not have been possible without the support from our partners at the U.S. Bureau of Land Management, U.S. Fish & Wildlife Service, CA Department of Fish & Wildlife (Region 6), Integral Ecology Research Center, U.S. Geological Survey, Shoshone Village, Inyo County Roads Department, and the Amargosa Conservancy.