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UC Davis Mammalian Ecology and Conservation Unit California Department of Fish & Wildlife

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.




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.


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.



Throwback Thursday: An Unusual Sea Otter Study

By Tom Batter, WIL Scientific Aid

Happy Throwback Thursday loyal readers!  Today we highlight an article describing an experimental approach by DFG to help curb losses to the abalone industry.  The experiment called for DFG to partner with commercial fisherman to supplement feed to the sea otter populations off the coasts of Monterey and San Luis Obispo counties.  The goal in mind was to make the sea otter’s southern migration unnecessary to help boost abalone production.  Quite an interesting approach that, to this author’s knowledge, was ineffective.  This excerpted page originally appeared in the 1967 November-December issue of Outdoor California.


Throwback Thursday: Marking Deer to Trace Migration Routes

By Tom Batter, WIL Scientific Aid

WIL Readers, get ready for some nostalgia!  We are catching up to social media trends and introducing a new feature to the blog: Throwback Thursday! We would like to share a glimpse of what wildlife management was like in the days of yore through articles, images, and reports from the past.

Today we bring you an article from Outdoor California’s June 1955 issue.  And yes, that’s Melvin R. Clover of collapsible Clover trap fame!


Tracking movement patterns of deer and other large mammals is still relevant to contemporary wildlife management. However, modern techniques have evolved along with modern technology.  Nowadays a study animal is more likely to be ear-tagged or fastened with a radio or GPS collar for research.  You’ll be hard pressed to find any bucks or does dyed for Mardi Gras festivities anymore!

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.

Two Bears Walk Into a Bar…

By Tom Batter, WIL Scientific Aid

An opening line like the title above is usually followed with some kind of a punch line.  Unfortunately you will find no joke here; two black bear cubs were recently confiscated from a local Kern County drinking establishment.  The presumably orphaned cubs came and went from the bar for about 8 weeks, where they were fed and played with by patrons, before the matter was brought to CDFW wildlife officer’s attention. As it is illegal to feed bears in the state of California, not to mention both human and wildlife health and welfare were at risk, the cubs were brought to the WIL for temporary housing and care.

The black bear cubs enjoy an afternoon nap in the hammock. (Photo courtesy J. Sherman)

The black bear cubs enjoy some R&R in their hammock. (Photo courtesy J. Sherman)

There was some hope that the cubs could be rehabilitated and released in accordance with department guidelines.  However, upon arrival at the WIL it was clear that these bears were far too habituated to humans.  After being evaluated by wildlife professionals, it was decided that these bears will have to be housed in captivity for the remainder of their lives.

It would be remiss of the WIL if we did not (again) direct our reader’s attention to the “Keep Me Wild” campaign.  Although it has become somewhat of a reoccurring theme on our blog, it is important to remember that California’s wildlife belongs in the wild. Although the folks feeding these cubs may have thought they were helping, the reality is that these cubs have been permanently habituated to people and will have to live a life in captivity.

The WIL has partnered with a high quality facility – the Houston Zoo in Houston, TX – to place both siblings together.  Upon their debut in their new enclosure last month, visitors watched as the cubs attempted a daring escape!  Zoo officials were able to safely and securely return them to their enclosure.  Leave it to California bear cubs to mess with Texas!

Remember: do not feed wild animals and do not handle wild animals; this endangers you and harms the wildlife as well.  Click here for steps to take should you come across nuisance, dangerous, or injured wildlife.

Confiscated Badger Finds a Home

By Tom Batter, WIL Scientific Aid

Quite recently, the WIL became a recipient of a new guest in our temporary animal holding facility: a bouncing, bright-eyed American badger (Taxidea taxus).  This particular mustelid arrived due to an unfortunate circumstance, but one that is all too common.  The badger was found as a kit, and then was harbored at a residence and kept as an exotic pet.  Upon receipt of a tip, CDFW wildlife officers confiscated the badger and brought it to the WIL for temporary housing until a more permanent solution could be reached.

American badgers are prolific diggers.  Here the badger can be seen "digging" a relaxing moment in our hammock. (Photo credit: Deana Clifford, WIL)

American badgers are prolific diggers. Here the badger can be seen “digging” a relaxing moment in the WIL hammock. (Photo credit: Deana Clifford, WIL)

Upon arrival at the WIL, it was clear that this badger was very habituated to humans thus rehabilitation and release were not an acceptable option. While not as ideal as if this badger had remained a wild animal without human interference, the WIL was able to find a permanent licensed facility that will offer professional care, nutrition, mental, and physical activity to ensure the badger’s well-being.

Although it is illegal to import, transport or possess any wild animals in the state of California, some may not recognize the reasoning as to why these laws and regulations are in place.

One of the main principles of the North American Model for Wildlife Management is that fish and wildlife belong equally to all.  Personally possessing wild animals violates this basic principle.  Furthermore, there are many risks to both humans and animals when wildlife are taken in and kept as “pets.”  These risks include:

  • Public safety: By their nature wild animals are unpredictable. They can unexpectedly bite, scratch, attack, etc. when put in a highly stressful environment such as captivity. Often wild animals that seem docile when young, will become dangerous as they grow up.  This captive situation will ultimately end up endangering owners, their family, friends and neighbors.
  • Habituation: When animals become used to situations they would otherwise avoid (i.e. human contact) they become habituated and reliant on humans for their survival.  A habituated animal cannot be returned to the wild as they could become a nuisance or danger to humans, jeopardizing the animal’s safety in return.
  • Disease: Wildlife can carry diseases dangerous to humans.  Since it is illegal to possess wild animals, it is more than likely they will lack any vaccination history. This only increases the chances of zoonotic transmission.
  • Animal welfare: Providing proper care for wildlife requires extensive knowledge of the life history of the species, as well as an extensive time investment to fully meet that animal’s needs.  Wildlife possess instincts and behaviors that are tied into a free-roaming state without human contact.  Residential homes cannot nurture instincts and stimulate natural behaviors that wildlife need to live a healthy life.  When CDFW finds illegally kept wildlife they are often malnourished and kept in unsanitary and sometimes inhumane conditions.  When captivity is unavoidable, it is best to leave captive wildlife care to appropriately permitted professionals, who have the knowledge and resources to properly care for the animal.

If you are aware of a situation where a wild animal is being illegally possessed, please contact CalTIP 24 hours, 7 days a week at:

1 888 DFG-CALTIP (888 334-2258)

Coexisting with California’s Wild Turkeys

By Tom Batter, Wildlife Investigations Lab Scientific Aid

Two turkeys feed in a residential area.  Photo credit Mark Meshriy

Two turkeys feed in a residential area. Photo credit Matt Meshriy.

The wild turkey (Meleagris gallopavo) is a wide-ranging upland game bird of North America.  There are five distinct subspecies of turkey, four of which have been transplanted into California at one time or another.  This includes the Eastern (M.g. silvestris), Rio grande (M.g. intermedia), Merriam’s (M.g. merriami), and Gould’s (M.g. mexicana) wild turkey. Today the most common subspecies found in California are the Rio grande and the Merriam’s varieties.

Wild turkeys were first introduced into California on Santa Cruz Island in 1877 by private ranchers (although there may be evidence that a turkey species existed in California as recently as the Pleistocene epoch).  Ranchers released these turkeys into the wild to have a supply of game birds readily available.  Throughout the early 20th century, introductions occurred several more times without a lasting effect.

The California Fish and Game Commission first purchased birds from Mexico in 1908 and released them into the San Bernardino Mountains.  Over twenty additional turkeys were farm-raised for future game-stocking purposes.  Between 1928 and 1951 these farm-raised birds continued to be released until the program’s termination due to lack of success.  During these twenty-three years, only three populations were successfully established.

It wasn’t until after 1959 that turkey populations began to take flight. A new management tool aided the propagation of the wild turkey in California.  The cannon-net trap was developed around this time, which increased trap-relocation feasibility and efficiency.

The rocket net is set over the food plot, ready to capture turkeys at the push of a button.  Photo credit M. Meshriy.

The cannon-net is set over the food plot, ready to capture turkeys at the push of a button. Photo credit M. Meshriy.

The cannon-net trap – a close relative of the “rocket net” – was utilized to increase wild turkey populations for sporting purposes in California.  Ironically, today cannon nets are typically used to catch and relocate turkeys that present problems for landowners, farmers, golf courses, and airports, among others.

The WIL recently took part in such a capture-relocation.  Homeowners in a rural residential area near Elk Grove contacted CDFW for help with a nuisance turkey situation.  CDFW officials assessed the situation and determined that relocating the turkeys to public wildlife areas was the best option. Factors considered by CDFW officials include: feasibility and probable success of the trapping effort, the safety of the public, the proximity to a suitable release site, and the availability of appropriately trained staff.

Turkeys are very vigilant creatures.  Living in a group puts more eyes on potential threats, and they will scatter at the slightest indication of danger.  So how do we lure turkeys in?  The answer is through a healthy dose of patience.

The first step is to determine where the turkeys in question go at certain times of the day.  Once their travel patterns can be predicted, bait is placed in a spot that is favorable to them as well as for the net and cannon — a cardboard mockup at this stage.  Bait is set for up to a week or more so the turkeys become aware of the food plot and habituated to the area. Once the flock takes to the bait, the real cannon and net are substituted for the fakes, the rocket is charged and ‘live’, and a waiting game begins.

A group of hens feed on the food plot in front of the rocket net.  This is a prime capture opportunity.

A group of hens feed on the food plot in front of the rocket net. This is a good capture opportunity.  Photo credit M. Meshriy.

Once there are enough birds on the bait to make processing them worthwhile (rarely is a second shot possible), and no birds are in danger of harm from the net, the cannon can be fired.  Field crew members quickly sprint to the birds under the net and physically restrain them to prevent injury.  Turkeys are transported back to the lab in specially designed carrying boxes.

WIL Environmental Scientist Krysta Rogers gets a transport box ready while Bob "Turkey Bob" and Upland Game Biologist Levi Souza remove captured turkeys from the netting.  Photo credit M. Meshriy.

WIL Environmental Scientist Krysta Rogers gets a transport box ready while Turkey Capture Specialist Bob “Turkey Bob” Klotz and Upland Game Biologist Levi Souza remove captured turkeys from the netting. Photo credit M. Meshriy.

When they arrive at the WIL, the turkeys receive a health assessment, a leg band and blood is collected in order to test for disease.  Once they are pronounced healthy, the turkeys are released into their new home. CDFW’s policy is to only release turkeys in areas away from human habitation, where there are already established populations and where they will be available for public enjoyment.

For more information on how to avoid conflicts with wild turkeys, click here.

For more information on the wild turkey’s life history, click here.

Three Bear Cubs Rehabilitated and Released

By Tom Batter, Wildlife Investigations Lab Scientific Aid

How near to good is what is wild!

– Henry David Thoreau, Walking, 1862

Two bear cubs stop to look back after they are released

Two bear cubs stop to look back after they are released. (Photo credit: Jamie Sherman)

The Wildlife Investigations Lab (WIL) is pleased to announce the rehabilitation and release of three black bear cubs.  Each cub was found orphaned in Southern California and brought to either the WIL care facility or to Lake Tahoe Wildlife Care (LTWC) for rehabilitation.

The three–one male and two females–eventually became united at the WIL care facility in Rancho Cordova. The two females were transferred from LTWC so all three bears could become familiar with one another and be released simultaneously.  WIL staff cared for the bears everyday, cleaning the pens and hiding food in trees and logs to get them used to “searching” for food.

Three bears in their temporary pen at the WIL. We brought in trees and logs to help get them used to foliage they will encounter in their natural habitat. (Photo credit: CDFW WIL)

WIL staff also took precautionary measures so that upon release the bears would retain their natural avoidance behavior of humans. We attached visual barriers to the perimeter of the pens, installed a trail camera in the pen for monitoring the bears, and limited the number of caregivers to a select few, minimizing human-bear interaction. This will give them a greater chance of survival.

They were pleased to be climbing trees again. (Photo credit J. Sherman)

They were pleased to be climbing trees again. (Photo credit: J. Sherman)

Prior to their release, the bears had ear tag radio transmitters attached to each of them. The transmitters have a range of 3-5 miles and can be detected from either the ground or from an airplane. These bears will be monitored continuously to gain knowledge on habitat use, dispersal distances, and reproduction (among other data) post-release.

The bears were released together back into their native home range in Southern California. Special thanks to Lake Tahoe Wildlife Care for their hard work and dedication to black bear rehab, as well as Lieutenant Martin Wall, Senior Environmental Scientist Rick Mayfield, Wildlife Environmental Scientist Rebecca Barboza, Capture Specialist Tim Glenner, Scientific Aid David Mollel, and Scientific Aid Jamie Sherman for their assistance with the release.

One of the bears scrambles into its' new stomping grounds. (Photo credit Jamie Sherman)

One of the bears scrambles into its’ new stomping grounds. (Photo credit: J. Sherman)