Drought and the Impact on California’s Wildlife

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?

Nearly 99% of California is abnormally dry, while 63% of the state is experiencing extreme drought (as of February 4, 2014).  Photo courtesy of the U.S. Drought Monitor.

Nearly 99% of California is “abnormally dry”, 67% of the state is experiencing “extreme drought”, and 10% is experiencing “exceptional drought” (as of February 4, 2014). Photo courtesy of the U.S. Drought Monitor.  Click here for the most up to date drought conditions in California.

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.

Dry conditions in cache creek, Yolo County.  Photo credit: Krysta Rogers, WIL.

Dry conditions at Cache Creek, Lake County, in late December 2013. Photo credit: Krysta Rogers, Wildlife Investigations Lab (WIL).

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.

Red tailed hawk.  Photo courtesy of the U.S. Fish & Wildlife Service

Drought impacts all trophic levels, including birds of prey such as the red-tailed hawk (pictured). Photo credit: U.S. Fish & Wildlife Service (USFWS).

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.

Large concentrations of waterfowl seek out remaining suitable habitat. Photo credit: Scott Flaherty, USFWS Pacific Southwest Region.

A variety of waterfowl species congregate at the Sacramento National Wildlife Refuge.  Photo credit: Scott Flaherty, USFWS Pacific Southwest Region.

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.

Many species of wildlife, such as mule deer, are capable of bouncing back after drought once favorable conditions return. Photo credit: T.A. Blake, USFWS

Many species of wildlife, such as mule deer, are capable of bouncing back after drought once conditions return to normal. Photo credit: T.A. Blake, USFWS

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.

Advertisements

Disease Surveillance Projects for Bighorn Sheep Completed in November

IMG_6565

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.

IMG_6570

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

IMG_6496

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

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

Growing Up Kit Fox

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.

California's Colorado Desert. This desert is a subdivision of the larger Sonoran Desert that encompasses Arizona, southeastern California, most of the Baja California peninsula, the islands of the Gulf of California, and much of the state of Sonora, Mexico. Map image courtesy of http://www.grabovrat.com.

California’s Colorado Desert. This desert is a subdivision of the larger Sonoran Desert that encompasses Arizona, southeastern California, most of the Baja California peninsula, the islands of the Gulf of California, and much of the state of Sonora, Mexico. Map image courtesy of http://www.grabovrat.com. Inset photo courtesy of Jaime Rudd.

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).

A mated pair of desert kit foxes. The male (top photo), stretches after a night of hunting for both his mate (bottom photo) and himself. These foxes both serve as disease sentinels in the California Department of Fish & Wildlife's (CDFW) desert kit fox disease monitoring project. Each fox is equipped with a radio collar that emits a unique frequency allowing biologists to monitor their survival after an outbreak of canine distemper virus (CDV) occurred in this desert valley the year before.

A mated pair of desert kit foxes. The male (top photo), stretches after a night of hunting for both his mate (bottom photo) and himself. These foxes both serve as disease sentinels in the California Department of Fish & Wildlife’s (CDFW) desert kit fox disease monitoring project. Each fox is equipped with a radio collar that emits a unique frequency allowing biologists to monitor their survival after an outbreak of canine distemper virus (CDV) occurred in this desert valley the year before. Photo courtesy of CDFW, Region 6.

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.

This female desert kit fox keeps a close eye on her den. She has 4 pups that her and her mate have been diligently been providing for.

This female desert kit fox keeps a close eye on her den. She has 4 pups that her and her mate have been diligently been providing for. Photo courtesy of CDFW, Region 6.

Once the pups are old enough, they are coaxed from their subterranean shelter under the watchful eye of their parents.

Already a couple of months old, the pups begin to explore a bit more while their parents remain close by.

Already a couple of months old, the pups begin to explore a bit more while their parents remain close by. Photo courtesy of CDFW, Region 6.

At nearly 3 months old, these pups are gaining more independence. While neither parent is seen in the photograph, they remain nearby.

At nearly 3 months old, these pups are gaining more independence. While neither parent is seen in the photograph, they remain nearby. Photo courtesy of CDFW, Region 6.

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.

Remote cameras captured these images of a bobcat (Lynx rufus, top photo) and a coyote (Canis latrans, bottom photo) passing through a desert kit fox den complex.

Remote cameras captured these images of a bobcat (Lynx rufus, top photo) and a coyote (Canis latrans, bottom photo) passing through a desert kit fox den complex. Photo courtesy of CDFW, Region 6.

But for now, the season is young and it is still a time when the desert truly gives life, both day and night.

This male desert kit fox looks over his 4 pups on a cool desert evening. Sunset is one of the most active times for desert kit foxes as the adults prepare to leave their den complexes (and their young) for an evening hunt.

This male desert kit fox looks over his 4 pups on a cool desert evening. Sunset is one of the most active times for desert kit foxes as the adults prepare to leave their den complexes (and their young) for an evening hunt. Photo courtesy of CDFW, Region 6.

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.

Pneumonia Outbreak in Desert Bighorn Sheep

Ewe with mild respiratory disease.

Desert bighorn ewe previously captured in the
Old Woman Mts. showing signs of mild respiratory disease

Wildlife professionals from the National Park Service, California Department of Fish and Wildlife (CDFW) and conservation organizations have been investigating an outbreak of respiratory disease in desert bighorn sheep in the Old Dad Peak / Kelso area of the Mojave National Preserve. This was first reported in mid-May 2013. Two diseased bighorn have been collected and submitted to the state diagnostic laboratory in San Bernardino.  Preliminary results confirm pneumonia.  Currently surveys are being conducted to determine the geographic extent of the outbreak. So far, the disease appears to be limited geographically but monitoring will continue.

To learn more, please see http://cdfgnews.wordpress.com/2013/06/06/scientists-search-for-clues-to-diseaseoutbreak-in-bighorn-sheep/

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

New Publication on Disease Research in Bobcats

Notoedric mange is a scabby, scaly, skin disease resulting from hypersensitivity reaction and infection by the feline mite,  Notoedres cati. The burrowing of the mite causes intense itch resulting in self-mutilation, secondary bacterial infection, and often death of affected felids if left untreated. Dr. Deana Clifford from the Wildlife Investigations Lab has coauthored a paper on notoedric mange in bobcats (Lynx rufus).  Development and validation of a fecal PCR assay for Notoedres cati and application to notoedric mange cases in bobcats (Lynx rufus) from northern California has been published in the April 2013 Journal of Wildlife Diseases.

This paper describes the efforts of a team of researchers to create a noninvasive diagnostic test, by developing and validating a novel PCR assay to detect N. cati DNA in fecal samples of bobcats (Lynx rufus) and used this assay to investigate a recent outbreak of mange in northern California, United States.

This paper, which was Dr. Nicole Stephenson’s Masters in Preventive Veterinary Medicine project, illustrates the benefits of scientific collaboration between agencies and academia.

The publication abstract can be found at:

Journal of Wildlife Diseases. April 2013 49:303-311; doi:10.7589/2012-05-136