Science Spotlight

  • May 14, 2021
bobcat on a dirt path

Young bobcat photographed for project, San Diego County

four scientists observing bobcat scat on a dirt path - click to enlarge in new window
Bobcat project staff (left to right) Liam Jasperse-Sjolander, John Nettles, Rudolplh Mena, Jessica Copeland using stick in process of determining if scat came from bobcat

bobcat trail camera on a dirt path with brush - click to enlarge in new window
Bobcat project camera station, Inyo County

bobcat in the snow with brush - click to enlarge in new window
Bobcat in snow, San Diego County

bobcat in sandy path with brush - click to enlarge in new window
Bobcat in sandy terrain, San Diego County

In the field of wildlife management, one of the most common and sometimes most difficult tasks is to obtain information about a particular species of animal in order to properly manage that species. The California Department of Fish and Wildlife (CDFW) was recently tasked by the State Legislature to conduct a demographic study of a particular species of animal that is known to be elusive and generally secretive, bobcats (Lynx rufus).

Officially known as the California Statewide Bobcat Population Monitoring Project, the study is happening because of a bobcat hunting ban that took effect in 2020. Part of the legislation requires the issue be revisited in 2025, but only after CDFW conducts a statewide population assessment, which will then lead to a science-based bobcat management plan.

Performing this study is complicated by a short timeline due to funding and personnel issues. Because the funding and the positions for those hired to conduct the study both end on June 30, 2022, the challenges of accomplishing this study become even greater. The effort began with forming the Bobcat Management Oversight Group (BOMOG), comprised of key individuals from around the state. That team includes the Deputy Director of Wildlife and Fisheries, the Chief of the Wildlife Branch, and key Regional and Program Managers. The BOMOG quickly realized that for the study to be successful, they would need to bring together a team of individuals from around the state. This resulted in the formation of the Technical Advisory Group (TAG), comprised of some of the top scientists and researchers within CDFW.

“The two groups will ensure project staff are employing consistent field protocols and methods, so the project is a success,” said Wildlife and Fisheries Division Deputy Director Stafford Lehr. “Instead of one unit being responsible, the entire department is responsible for this project.”

The TAG was asked to quickly (within two months) develop a study plan to guide the implementation of the study. The group not only met that deadline but also provided a draft capture plan as well as planned and initiated a pilot project to test the plan prior to its full implementation.

“The TAG’s accomplishments in this very short timeline are a testament to their talent and dedication,” said South Coast Regional Wildlife Program Manager and TAG project lead Rick Mayfield. “This project would not have been possible without their hard work.”

With the planning process completed, CDFW hired a team of 20 people specifically for the project. One was Senior Environmental Scientist Rachel Roberts who, as the lead over this group, faces the challenge of implementation and completion of the study by June 30, 2022. At that point, the data collection will end, and the analysis and creation of a statewide bobcat management plan will begin. This plan, due to be completed by January 2025, will cover all aspects of bobcat management, from demographic information to the effects of habitat loss, wildfires and urbanization on the species.

“It’s kind of funny because we know a lot about bobcats and nothing at the same time,” said Roberts.  “We see them in a lot of places and we think that they tend to do well on the edges of urban areas. There have been projects across that state that have collared bobcats, so we have some idea of a home range, but we don’t know specifically all of the different habitats they’re residing in. We have anecdotes of them in orchards, or at high elevations, but that’s one study in one area. This project is trying to get truly to where bobcats are and where they aren’t.”

A few things we do know about bobcats in California: they’re about one fourth the size of a mountain lion, weighing between 12 and 25 pounds depending on environmental conditions. They prey on rabbits, rodents, birds, insects, reptiles and occasionally chickens. Their current population is estimated between 70,000-100,000 statewide. Pelage (fur) markings on their body, legs and face make it possible to distinguish one from another.

To get the most accurate information on California’s bobcat population, Roberts and her team will collect scat samples for fecal DNA analysis. This analysis allows for the individual identification necessary for determining population size via a capture/recapture model. Complementing the scat analysis in assessing the bobcat population, the teams will gather data and photographs in 48 different study areas. Each study area will be 40 square kilometers (just over 15 square miles) and have 80 cameras mounted to record still images of anything that moves in that area, day and night. The motion-activated cameras will shoot images in each study area for six weeks, before being relocated to the next study area.

“We're taking a three-shot, rapid-fire burst with two cameras facing each other at each camera station,” said Roberts. “We're hoping to be able to get photos of the pelage patterns on each bobcat, especially on the insides of their legs – that’s how you can really identify individuals. We're hoping to see these cats more than once so that we may be able to run the capture/recapture model to estimate bobcat density with the camera data as a complement to the scat data.”

“To get their densities and to be able to keep track of individual bobcats, so we know we’re not double-counting them, the DNA in scat is definitely the gold standard,” said Brett Furnas, a biostatistician with the CDFW Wildlife Investigations Lab. “If it’s not a bobcat sample we’re collecting it might be a coyote instead. We confirm that with genetic analysis to make sure what we’re counting is indeed from a bobcat, so we can determine individuals to count them.” Furnas is no stranger to this kind of work. “I’ve worked a lot on deer, so this method of going around and picking up bobcat scat is what we first applied to deer,’ he said. “I’ve also been working with Justin Dellinger (lead of CDFW’s mountain lion monitoring project), so this is the third project in which we’re using genetic information.”

There’s one key difference between the gathering of scat DNA and taking of photographs. Project team members will control how much scat they gather and submit for DNA analysis. Team members won’t have control of the amount of photos that are taken by the nearly 500 hundred motion-activated cameras scattered around the state. The number of photographs to sort through and categorize would be overwhelming, if not for a new company, Wildlife Insights, which stores the images and identifies the animals photographed in the study area.

“All of those photos are uploaded to the cloud and when you open the interface, it has already tagged the animals,” said Roberts. “If it sees turkeys, it has already tagged it. We’re just going in and making sure it’s correct. And, you can just pull out the species that you are interested in. Before, this was all super clunky. We did a pilot study and there were hundreds of thousands of photos, just from two cameras set up for eight weeks.”

Roberts said she’ll visit most of the study areas over the course of the study, but she’d be perfectly happy making it to all 48. The challenge of measuring California’s bobcat population is exactly what she wants to be doing.

Deputy Director Stafford Lehr sees the importance of this work for years to come. “We are striving for a more cohesive approach to applied management throughout the department and we hope this is an improved method of program delivery,” he said. “The importance of having a robust management plan that withstands scientific review and public scrutiny will pay dividends in future programs for the department.”

CDFW Photos

Categories: Science Spotlight
  • May 10, 2021
Bear in a tree

A female black bear takes in her surroundings from the safety of a pine tree after being trapped, tagged and hazed by state parks and wildlife personnel last fall.

As the Lake Tahoe Basin’s black bears emerge from their winter slow-down and slumber, campground managers, biologists, park rangers and wildlife officers hope to have a new tool at their disposal to help manage the human-bear conflicts certain to arise this spring and summer: a growing catalogue of Tahoe’s bear population.

Since the fall of 2019, the California Department of Fish and Wildlife (CDFW) and California State Parks have teamed up to trap, tag and haze as many Tahoe bears as possible to identify individual bears, build a genetic database of the population, study its overall health, and whether related bears are passing down problem behaviors from one generation to the next. Eighteen bears have been trapped to date – four of those being recaptures. Genetic material is collected and each bear is outfitted with an identifying ear tag before release.

This May, CDFW will broaden the effort and team up with the U.S. Forest Service to trap, tag and haze additional bears within the Tahoe National Forest. The trapping takes place in short windows during the early spring and late fall off-seasons at Tahoe-area campgrounds. The bears are hazed – but not harmed – upon release to provide a negative human interaction and to see whether the experience will keep them away from campgrounds and people in the future.

In this video, Shelly Blair, CDFW’s wildlife biologist for El Dorado and Alpine counties, and Sarinah Simons, California State Parks Sierra District human-bear management specialist, explain the innovative collaboration and scientific work during trapping efforts last fall.


CDFW Photo

Categories: Science Spotlight
  • May 6, 2021
tractor plowing a field preparing the field to plant

A three-acre field is planted with a combination of sunflower and safflower seeds to provide food for mourning doves – and a place for dove hunters to hunt come Sept. 1.

Scientist Brian Young sitting in the back of a truck with seeds
Oroville Wildlife Area Manager AJ Dill sits on the back of a flatbed truck stacked with sacks of safflower and sunflower seed and fertilizer for the spring planting season.

Scientist Brian Young holding soil in a field
Fish and Wildlife Technician Brian Young holds handfuls of safflower and sunflower seeds prior to planting.

Field of safflower and sunflower seeds
Upland habitat planted in the fall is lush and colorful in the spring providing important nesting habitat for wild mallards and Canada geese near the shores of the Thermalito Afterbay.

It only took Brian Young about two laps around the freshly plowed, three-acre field before the red-winged blackbirds started showing up.

A fish and wildlife technician at the Oroville Wildlife Area in Butte County, Young was piloting a John Deere 5075M utility tractor along the shores of the Thermalito Afterbay in mid-April, scattering a mix of sunflower and safflower seeds behind him. The red-winged blackbirds were taking full advantage of the easy meal.

Once seeded, Young would retrace his route, distribute fertilizer and hope for the best. A quarter-mile away along a gently sloping hillside another John Deere tractor was at work covering up with soil another plowed, seeded and fertilized field.

Spring is planting season at the 12,000-acre Oroville Wildlife Area and at dozens of other California Department of Fish and Wildlife (CDFW) properties up and down the state as crop fields are prepared for mourning doves – and the dove hunting season that begins in September. And while planted to attract doves and provide public land dove hunting opportunities, the crop fields also will provide food and habitat for all manner of wildlife, including those red-winged blackbirds.

“Native songbirds, tricolored blackbirds, wild turkeys – you name it. Just about anything that flies – with the exception of our raptors – will be out here feeding in these fields throughout the fall,” explained AJ Dill, the Oroville Wildlife Area manager since 2013.

Safflower and sunflower are mourning dove favorites. A couple weeks before the Sept. 1 dove season opener, the Oroville Wildlife Area’s tractors will be back to knock down the safflower and sunflower stalks and scatter the seeds to the ground where doves can access them more easily.

Mourning doves are especially attracted to harvested agricultural fields and the food plots at Oroville and other CDFW properties can provide fast action for public land dove hunters on opening day and places to hunt throughout the season. At Oroville, however, hunters have to do their homework. Unlike some other wildlife areas, Oroville does not provide hunting maps or directions to its dove fields. Hunters have to scout and find them on their own. A Type C wildlife area, Oroville is open daily to dove hunting during California’s two dove seasons. No special permits, reservations or fees are required provided hunters are otherwise properly licensed.

This spring, the Oroville Wildlife Area will plant about 60 acres of safflower and sunflower among 16 different fields varying in size throughout the wildlife area. The dove fields are spaced out to spread out the hunters, prevent overcrowding and foster safer hunting conditions.

How productive the fields ultimately become will depend on many factors – but none more so than weather.

“Everything we do out here is dryland farming. We don’t irrigate. So we really need a shot of water – just a little bit of rain – to get things going,” Dill said.

A significant portion of the Oroville Wildlife Area’s upland habitat work also takes place in the fall when 80 acres of nesting cover are planted annually – typically some combination of vetch, barley, peas, wheat, oats, clover and grasses – along the shores of the Thermalito Afterbay to benefit nesting ducks and geese in the spring. The wildlife area maintains about 240 managed acres of upland nesting habitat in total, the dense cover providing nesting hens, their eggs and newborns safety and protection from predators.

As with the planted dove fields, the lush, colorful, nesting habitat provides secondary benefits to other grasslands-dependent species, particularly pollinators such as bumblebees, honeybees and butterflies. The loss of grassland and upland habitat throughout California has contributed to the decline of wild mallards, wild pheasants, pollinators and other species and adds a sense of urgency and heightened importance to the upland habitat work at the Oroville Wildlife Area and other CDFW properties throughout the year.


CDFW Photos

Categories: Science Spotlight
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