New publication describes the prevalence and impacts of toxoplasmosis in Amargosa voles

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.

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BOLO for BTPI

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!

Adult band-tailed pigeon showing the characteristic white crescent and iridescent greenish-bronze patch of feathers on the hindneck. Photo by Gary Kramer, 2008.

Adult band-tailed pigeon showing the characteristic white crescent and iridescent greenish-bronze patch of feathers on the hind-neck. Photo by Gary Kramer, 2008.

Acorns on a coast live oak (Quercus agrifolia) in Monterey County, a favoriate wintertime food of band-tailed pigeons. Photo by Krysta Rogers, 2011.

Acorns on a coast live oak (Quercus agrifolia), a favorite wintertime food of band-tailed pigeons. Photo by Krysta Rogers, 2011.

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.

Flock of band-tailed pigeons in oak tree in Santa Clara County. Photo by Krysta Rogers, 2014.

Flock of band-tailed pigeons in oak tree in Santa Clara County. Photo by Krysta Rogers, 2014.

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.

An adult band-tailed pigeon showing signs of infection with Trichomonas parasites. Notice the drooped wings, ruffled feathers, and open-mouth breathing. Photo by Krysta Rogers, 2012.

An adult band-tailed pigeon showing signs of infection with Trichomonas parasites. Notice the drooped wings, ruffled feathers, and open-mouth breathing. Photo by Krysta Rogers, 2012.

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.

Steps towards restoring an endangered species (Part II)

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.

Healthy habitat at the recipient site that voles were translocated into.

Healthy habitat at the recipient site that voles were translocated into. Photo courtesy of Risa Pesapane

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.

A "hard" release of a collared vole at the donor site.

A “hard” release of a collared vole at the source site.

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.

Janet Foley (UC Davis Principal Investigator) conducting radio telemetry for collared Amargosa voles.

Janet Foley (UC Davis Co-Principal Investigator) uses and antenna and receiver to listen for the signals of radio- collared Amargosa voles. Photo courtesy of Risa Pesapane.

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.

Stephanie Castle, Risa Pesapane, and Amanda Poulsen (UC Davis Graduate Students) conducting a point count for Amargosa vole predators.

Stephanie Castle, Risa Pesapane, and Amanda Poulsen (UC Davis Graduate Students) conduct a point count for Amargosa vole predators.

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.

 

Throwback Thursday: Controlled Burns for Improving Wildlife Habitat

By Tom Batter, WIL Scientific Aid

Today we feature an article that looks at how the Department of Fish & Game utilized controlled burns as a management tool.  As the article states, fire has influenced plant and animal species for centuries.  It is a common misconception that many animals are killed by fire.  In fact the primary effect fire has on wildlife is habitat alteration.  Some plant species have actually adapted to cope with fire. This article mentions pyriscence as an example. Pyriscence is when the maturation and release of seeds is fully or partially triggered by smoke and/or fire resulting in new plant crops.

Managing habitat with fire also reduces fire risk by lowering the fuel load.  Large fuel loads -dead plant material and brush build up- that are allowed to accumulate over time cause fires to burn hotter and spread more rapidly.  These are the types of wildfires that are more likely to become dangerous and destructive to people and property.

Using fire as a tool is still an important technique in managing habitat for various species of plants and animals today.  This article originally appeared in the November-December issue of Outdoor California in 1973.

NovDec73

 

 

Two New Publications on Band-tailed Pigeons

The first two papers on disease research in band-tailed pigeons have been published. The papers are the result of a collaboration between the UC Davis Wildlife Health Center and the CDFW Wildlife Investigations Lab.

In the first article, Trichomonas stableri n. sp., an agent of trichomonosis in Pacific Coast band-tailed pigeons, Yvette Girard, Krysta Rogers, and co-authors, describe a newly discovered parasite found in band-tailed pigeons. The second article, Dual-pathogen etiology of avian trichomonosis in a declining band-tailed pigeon population, discusses rates of infection of Trichomonas parasites in band-tailed pigeons and sympatric avian species.

Pacific Coast band-tailed pigeon.

Pacific Coast band-tailed pigeon. Note the characteristic white crescent and iridescent greenish-bronze patch of feathers on the hindneck and black-band on the tail. Photo by Krysta Rogers, 2013.

Click here to read the recent UC Davis news release.

Click here to read about the new parasite.

Click here to read about Trichomonas spp. infection rates.

If you have any questions about the project, or would like to report sick or dead band-tailed pigeons, contact Krysta Rogers at 916-358-1662.

Throwback Thursday: On Wildlife Management

By Tom Batter, WIL Scientific Aid

They say you can’t know where you’re going if you don’t know where you came from.  Our latest installment of Throwback Thursday takes a look at an article from the November 1956 issue of Outdoor California discussing what wildlife management is, and why it is needed (and a bonus for any poetry fans out there).

By today’s standards, we would substitute ‘game’ for ‘wildlife’ in the article title as the author, Jack R. Beer, takes a very game-centric approach in his discussion.  Which makes sense considering his job title was ‘Game Manager.’  Regardless, the main points in this article still apply to wildlife management today with the understanding that the principles expand to encompass all wildlife, not just those species which are harvested.

Nov56

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.