This spring the Wildlife Investigations Laboratory assisted with 8 large mammal captures throughout California. Wildlife capture projects are conducted to help biologists and veterinarians assess the health of these herds through biological sampling, to place GPS collars on the animals to monitor movement and help study habitat use, and for translocating animals. A total of 207 animals were captured including 132 deer, 21 pronghorn antelope, 36 elk and 18 bighorn sheep. Below is a small collection of photos from our month in the field.
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.
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.
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.
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
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.
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.
By Tom Batter, WIL Scientific Aid
California has been experiencing persistent dry conditions since 2012. According to the National Drought Mitigation Center at the University of Nebraska-Lincoln, 99% of California is currently abnormally dry, 67% of California is in extreme drought, and almost 10% is experiencing exceptional drought — and it may not let up soon. The implication of a drought emergency is relatively straightforward: there is a severe lack of water. This lack of water affects Californians in many ways, be it economically or socially. But how does it affect the state’s wildlife?
California’s wildlife depends on water just as it’s citizens do. With water resources becoming increasingly rare, a “domino effect” takes place in the ecosystem. Drought conditions negatively impact habitat through resource deterioration and wildfire, causing migration and behavior changes of animals. Wildlife become concentrated in remaining suitable habitat, increasing chances for disease outbreaks due to close contact.
It begins at the producer level. As drought intensity increases, vegetation growth is stymied. Plants that lack necessary water resources respond by reducing new stem growth while previously produced stems will shrivel and die. The obvious effect from lowered plant production is a reduction in food availability for herbivores. This in turn reduces populations of insects, reptiles, wild rodents, and hares which many small carnivores and raptors rely upon for food.
With lower food availability, animals tap into their body’s fat reserves. Utilizing fat reserves will ultimately lead to starvation for wildlife whose nutritional needs are not eventually fulfilled. Beginning in mid-December, WIL began documenting increased mortality of young red-tailed hawks in central and southern California. Investigation revealed poor body condition, emaciation, and secondary bacterial or fungal infections. A similar event occurred the previous winter, also in dry conditions.
Reduced plant growth also negatively affects available cover for wildlife. Cover is an important element for prey species to evade predators. As plant life diminishes, landscapes become more open. For some wildlife, such as ground nesting birds, the likelihood of predation increases as these drought ridden landscapes open up.
With the odds already stacked against them, wildlife in drought conditions are also forced to travel greater distances in search of food and water resources. Some behavior changes may take place as a result; for example, typically nocturnal species such as raccoons and opossums may remain active well into the daylight hours seeking food. The extra effort for nutrients puts these animals at an increased risk of exhaustion, starvation, predation, and disease.
As drought conditions persist, animals will seek out alternative habitats that have more favorable conditions for survival. Areas where food and water are still available will attract many species to a relatively small area. Predation rates are likely to increase as predators can more easily focus on a centralized group of prey. Furthermore, large concentrations of wild animals increase the odds for disease outbreaks that could decrease populations.
In fact, this winter WIL has already investigated several avian cholera outbreaks throughout California. Large numbers of ducks, geese, and swans spend the winter on the state’s many ponds and lakes. The current lack of precipitation has reduced the amount of habitat available for these birds, forcing them to become concentrated in locations where water remains. Close contact among waterfowl allows a bacterial disease like avian cholera to spread very rapidly, resulting in the death of hundreds to thousands of birds.
While these impacts of drought do indeed create dire circumstances for wildlife, it is important to remember that droughts are natural phenomena. Wildlife and drought have coexisted for generations upon generations. Generally speaking, wildlife populations are resilient and are able to bounce back from drought events once typical weather patterns return. For example, in the early 1960s severe winter drought contributed to extreme deer die-offs in Texas. When rainfall levels returned to normal, the deer population was able to rebound in only one year.
During these hard times, it may be tempting to “rescue” or “save” an animal that is seeking food and water. It is entirely possible that more wildlife will make their way into urban and residential areas in an attempt to find nutrients. It would be a disservice to both human and animal to offer handouts, for similar reasons it is inappropriate to keep wildlife as pets. This natural drought event will eventually pass, and when it does, CDFW and WIL staff would rather see California’s fauna remain reliant upon themselves rather than their human counterparts.
If you have acorns in your area, be on the look out for band-tailed pigeons this winter. Band-tailed pigeons are California’s only native pigeon and this time of year, they will fly great distances to find acorns. Band-tailed pigeons are one of the rare bird species that will actually swallow acorns whole! Unfortunately, this behavior also makes them more susceptible to Trichomonosis, 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 bird’s mouth or esophagus. As the lesions become larger, the pigeons can no longer swallow acorns, leading to weight loss and eventually death. The lesions also may cause the pigeon to suffocate, if they block the airway.
While this disease can make pigeons sick any time of the year, large-scale die-offs only occur during the winter, in some years. The last series of mortality events were reported in 2012 in California, when up to 10,000 pigeons were estimated to have died between December and March. Recent research by CDFW suggests that these mortality events are more likely to occur in winters with low precipitation, similar to the conditions we’ve been experiencing so far this winter.
So, if you have acorns, be on the lookout for band-tailed pigeons and enjoy watching them comically hang from the branches as they try to reach an acorn. Hopefully, the pigeons will not experience any die-offs this winter. However, if you do happen to see 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.
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.
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
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:
California roadkill tracking:
Wildlife heath information:
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.
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).
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.
Once the pups are old enough, they are coaxed from their subterranean shelter under the watchful eye of their parents.
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.
But for now, the season is young and it is still a time when the desert truly gives life, both day and night.
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.