Featured Scientist

A Sierra Nevada red fox dashes into the wilderness after being caught and released as part of an ongoing CDFW study. CDFW image by Corrie McFarland.


Jennifer Carlson on a Roosevelt elk capture in Humboldt County.

Jennifer Carlson is an environmental scientist with the Wildlife Management Program in CDFW’s Northern Region. Based out of Redding, she is one of two unit biologists covering Shasta and Trinity counties. Her biggest current project is working on Sierra Nevada red fox, a state-threatened species, in the Lassen Peak Region, and she is a member of the long-standing Sierra Nevada Red Fox Working Group. In addition, Jennifer has an elk project waiting in the wings and recently conducted the first helicopter survey in her area to attempt to count the different herds in her unit. Her other responsibilities include responding to human-wildlife conflicts and providing expertise and advice to hunters and the public.

Jennifer received her Bachelor of Science degree in Wildlife Management with a minor in Statistics from Humboldt State University in 1999. She also received her Master of Science in Forestry from Cal Poly San Luis Obispo in 2006. She started her career with CDFW in 2005 in the Timber Harvest Review program in the Northern Region. In 2012, she joined the Wildlife Management Program in her current position. When she is not working, she enjoys spending time with her family skiing, camping, hiking, hunting and fishing.

Who or what inspired you to become a scientist?

My family was instrumental in my inspiration to become a wildlife biologist – particularly my dad. He earned his B.S. in Biology and Chemistry and was a self-taught entomologist. He worked for the department in the 1960s as a scientific aid. But at that time it was difficult to get on with the department as a permanent employee, and he never did get hired. Growing up he would take us on nature hikes and quiz us on all the flora and fauna we saw along the way. His own love of the outdoors started with camping and fishing in the central Sierra Nevada with his grandparents (my great-grandparents) when he was a child and it became a family tradition. It became a summer ritual that we carry on today with my own family – a total of four generations!

What is a typical day like for you at work?

As a unit biologist you don’t always know what the day will hold. When one of the aspects of the job is dealing with nuisance wildlife and the public, you could be getting called out to dart a bear that has found its way into town, or a deer that is stuck in a fence. It can include visiting sites to assess property damage caused by a bear, mountain lion, beaver, or bobcat and issuing a depredation permit. In addition to that there are annual wildlife surveys I am responsible for, including deer, band-tailed pigeons, pronghorn antelope, and elk. I also have special projects I work on and am responsible for overseeing, particularly the Sierra Nevada red fox project in the Lassen Peak area. Running a project from start to finish is very time consuming and takes up a lot of my day, especially during the height of the field season. I help out on other projects that my colleagues run, including capturing and collaring deer and elk, fecal DNA projects on deer and elk, and baited camera stations for mid-size carnivores.

What has been the most challenging, and rewarding aspects, of your study of the Sierra Nevada red fox?

We don’t know much about the Sierra Nevada red fox. We think their numbers in the Lassen area may be less than 20 -- we have a minimum population count based on collaring and genetics of 11 individuals currently. Small populations are difficult to study so this one has been a challenge from the start, and it has been compounded by the rugged terrain and conditions that these foxes live in all year-round. With the snowfall we had this past winter, maintaining functional traps has been a challenge, as has keeping our satellite collars working properly. No matter how much we try to alleviate all the obstacles we anticipate, there will always be a level of uncertainty when working on a wild animal in its natural environment that you must accept as a wildlife biologist. But there are great things we have learned from this project that we didn’t know before. For example, we found and documented the first Sierra Nevada red fox den since the early 1900s. We have some amazing video footage of red fox behavior at the den site as well as vocalizations never heard before. We captured, collared and released back into the wild three females and one male red fox. We documented for the first time an inbreeding event where siblings reproduced and had one pup together. We have also learned that these foxes don’t stay at a low elevation throughout the entire winter, as had previously been thought; instead, they will travel back and forth to the higher elevations around Lassen Peak that we thought they only used in the summer.

Tell us about your upcoming elk study.

The goal of the elk study is to estimate abundance, which is difficult with a wide-ranging species that often uses locations that hinder traditional survey methods. To do this, we will capture and collar cow elk in several different herds to learn their movement patterns and apply two different survey techniques to help estimate abundance. The primary technique will be using a helicopter to survey the different herds and count all individuals sighted in each group – both collared and uncollared. Using this data, you can create a “sight ability” model to estimate how elk many you missed and calculate the population size. The other technique would involve extracting DNA from fecal pellets to identify unique individuals and estimate number of individuals in the population. The satellite radio collars will also give us valuable data on habitat use, resource selection, behavior, disease and cause-specific mortality. This will allow the department to develop a long-term elk monitoring program that our recently released Elk Management Plan outlines for the Northern Region. The project will take place primarily in Shasta County (east of Interstate 5) and possibly Trinity County and will hopefully start in the late fall or early winter of this year.

If you had free reign and unlimited funding, what scientific project would you most like to undertake?

It would be hard for me to pick just one project! I would like to help restore a genetically healthy Sierra Nevada red fox population to its historic range. The Sierra Nevada red fox populations that we have left in the state are severely inbred or their genetics have been compromised by other montane (high-elevation) sub-species and/or non-native individuals that have entered the populations. In the last few years we have learned that there are also Sierra Nevada red foxes in the central and southern Cascade mountains of Oregon, although we don’t know the extent or status of that population. I would implement a translocation project that would move individual foxes from their current population into a new one to facilitate “genetic mixing” and increase genetic health. Once we had genetically healthy populations, then I would like to see them reintroduced into areas that they used to occupy, like on and around Mt. Shasta.

I also would like to undertake a massive elk project that was scientifically sound and robust, with an army of people working on it in the Northern Region. With those resources, we should be able to come up with an accurate population size for elk in our region relatively quickly.

What is the best thing about being an environmental scientist?

One of the best things about my job is that I get to be in the outdoors and explore places I never would have been to otherwise. To be able to study one of the rarest mammals in California, the Sierra Nevada red fox, and provide new information on the life history of this elusive canid has been one of the highlights of my career. Flying in a helicopter counting big game species is something I always dreamed about when I was in college and now I am doing it. Some days I have said to myself, I can’t believe I am getting paid to hike on this trail or fly in a helicopter today!

CDFW Photos. Top Photo: Jennifer Carlson cradles a Sierra Nevada red fox that was captured and collared in the Lassen National Forest. CDFW image by Pat Sater.

Marcia Grefsrud is an environmental scientist with CDFW’s Bay Delta Region. She spends much of her time working in the field, reviewing requests for incidental take permits and streambed alteration agreements. Her work helps to ensure that urban development does not destroy the resources upon which wildlife depend. She also serves as an advocate for many vulnerable species in the Bay Area, most notably the California tiger salamander (Ambystoma californiense), a stocky black and yellow amphibian that inhabits many of the stock ponds and grasslands in Alameda County.

Marcia took an unconventional path to her current position. She has attended a number of colleges and universities from as far north as Bemidji, Minnesota to as far south and east as Puerto Rico and as far west as Cal State East Bay in Hayward. A former petty officer in the US Navy, she also served as a CDFW wildlife officer before becoming a scientist.

Outside of work, Marcia is also skilled photographer with an extensive portfolio of wildlife images. She is particularly good at “macro-photography” – capturing small details of a dragonfly’s wing or a bushtit’s feathered breast. Her images are often featured on CDFW’s social media pages and in publications.

Who or what inspired you to become a scientist?

I grew up during the time of “Wild Kingdom,” “The Undersea World of Jacques Cousteau” and “Jaws,” and I became fascinated with marine biology, especially sharks. My passion at the time was to be a marine biologist, but there obviously weren’t any colleges in Minnesota offering that field of study and I didn’t have the money to move out of state. Eventually, I couldn’t afford to stay in college, so I opted for something else – the Navy. That decision sent me on an entirely different career track of advanced electronics and cryptology.

How did you come to work for CDFW?

I moved to California after accepting a job as a Navy Tech Rep/Project Manager at Mare Island Naval Shipyard in Vallejo. That job required extensive overseas and stateside travel and long work hours often in remote military bases such as Iceland and Adak, Alaska. The base closures left two options – I could relocate to San Diego or find another job. I opted to leave the federal government and return to school with the goal of studying raptor biology. But life had other plans, so after graduating from CDFW’s Resource Academy, I worked as a fish and game warden for three years. I made the jump to the scientific side 17 years ago.

Your job involves working with developers and builders to issue permits in the East Bay. Why is that important?

I cover all of Alameda County, which includes the highly urbanized area along the easternmost portion of San Francisco Bay and the more rural, eastern portion that supports ranching, with an urban/suburban center located in the Tri-Valley region. The county is approximately 50 percent agricultural land and 50 percent urban lands. Then there is the Altamont area of Alameda County, which is known for the wind turbines populating the hillsides. Combined, each of these areas make Alameda County one of the busiest counties in the region for Habitat Conservation. For example, from 2010-2015, approximately 668 acres of habitat in Alameda County was permanently lost as a result of residential development alone. But approximately 2,066 acres of habitat has been permanently conserved as a result of incidental take permits issued for those residential developments.

What is a typical day like for you at work?

When I’m in the office, I spend the day answering emails and telephone calls. I split my time between writing permits and agreements, reviewing conservation lands packages and monitoring reports. On the fortunate days when I’m in the field, I could be doing compliance checks, visiting project sites or attending meetings. If I’m really fortunate, I could be doing stream or pond surveys.

What is your favorite species to interact with or study?

Hands down, the California tiger salamander. They are my favorite probably because there is so much more to learn about them and I love the challenge. There have been many studies but there are still gaps in our knowledge that may never be filled. Plus, they are so darn cute!

What is the most rewarding project that you’ve worked on for CDFW?

The California Endangered Species Act (CESA) was intended to help protect wildlife and their habitats, but it can also create unintended hurdles. For instance, in Alameda County, privately owned stock ponds – which are prime breeding grounds for the California tiger salamander – have a finite lifespan, and may require maintenance and upkeep in order to function properly. When California tiger salamanders became a candidate species for state listing in 2009, new permitting and mitigation requirements went into effect. Because any land improvements or changes within CTS habitat were now subject to strict oversight, I became concerned that some ranchers would let their stock ponds go unmaintained rather than attempt to go through the permitting process.

After doing a lot of digging, I found a little-used section of the Fish and Game Code regarding Voluntary Local Programs (VLPs). These are similar to the state and federal Safe Harbor Agreement program, except the VLP is specifically for routine and ongoing agricultural activities on farms and ranches that encourage habitat for state listed or candidate species. A VLP must include management practices that will avoid and minimize harm while encouraging the enhancement of habitat. Landowners or ranchers that sign up with the local VLP agree to voluntarily carry out specific habitat improvements and to abide by avoidance and minimization measures. These measures are developed and agreed upon by CDFW, the program administrator (in this case, the Alameda County Resource Conservation District), the California Department of Food and Agriculture and other agricultural experts.

Ranchers can then perform routine and ongoing agricultural activities and necessary maintenance to stock ponds, roads, streams and other agreed-upon practices without risk of violating CESA. Even though we had to “give a little,” the Alameda County VLP has helped CDFW build trusting relationships with the Resource Conservation District and the local ranching community, and has ultimately allowed more potential breeding ponds to be repaired in a timely manner.

What is the most challenging aspect of your career as an environmental scientist?

The enormous amount of work and the limitations of our job duties.

If you had free reign and unlimited funding, what scientific project would you most like to do?

At the moment I want to do a study on teeth patterns of California tiger salamanders compared to hybrids and non-natives. One study I looked at found that considerable variation in tooth morphology may be found between species of the same genus. There is a possibility that the teeth patterns between the native salamanders, non-natives and hybrids are different. If so, it may provide another indicator to determine whether or not a specific animal is pure CTS or hybrid.

What is it about the work you do that you’d most like us to know?

Some people think Habitat Conservation work is boring and/or not important because it doesn’t sound as exciting as chasing poachers or studying wildlife. Sometimes the work is tedious, but what we do is extremely important because without it we would face more species’ extinction and destruction of terrestrial and aquatic habitat.

How does your interest in photography intersect with your work as a scientist?

I have had a lifelong interest in photography and art, but only recently started to explore photography as art. In addition to photographing wildlife (which has its challenges), I am drawn to the old, obscure, dilapidated and overlooked parts of our environment -- from the tiny mushroom to the broken-down piano dumped on the side of the road. One of the joys I find with photography is being able to show beauty in things that often go unnoticed.

One of the cool things about photography for me is it allows me to visually study some of these animals without physically capturing them. It is amazing what you learn when you are looking at a macro, like the wing structure of a dragonfly or embryos of foothill yellow-legged frogs. I’ve also been able to capture some remarkable photos of birds in action. I have a series of photos of an osprey repeatedly dive bombing a bald eagle. Then another series with a red-tailed hawk attacking a bald eagle that was trying to steal a fish from an osprey. One photo that will hopefully be published in a short note soon is of a peregrine falcon that predated a federally and state protected Ridgway’s rail. The photos are not National Geographic worthy, but they do tell stories!

Do you have any advice for people considering careers in science or natural resources?

With so much information available on the Internet now, I would start by exploring government and non-profit websites to find volunteer opportunities. The more field experience they can get the better off they will be both in finding a job and really beginning to find their passion. Finally, I would recommend when they do find something they are passionate about then stay focused and go for it!