By Jasjeet Dhanota
The iconic bear on the California state flag is a grizzly – a species that hasn’t been spotted in California since 1924. The grizzly bear's meddlesome nature toward livestock didn't sit well with the settlers who rapidly populated California in the late 1800s. Just 75 years after gold was discovered in California, the grizzly bear population in the state had been decimated.
Black bears, on the other hand, remained, and their lone competitor was no longer in the picture. What followed was a steep increase in black bear population and habitat range that continues to this day. It is estimated that there are at least 30,000 black bears in California and, as time passes, they’re being spotted farther and farther up the coastal range, which was once grizzly habitat.
Jamie Sherman, a fourth-year PhD student in the Animal Biology graduate group at the UC Davis School of Veterinary Medicine, is an up-and-coming black bear expert. She is working with Dr. Holly Ernest and the California Department of Fish and Wildlife to research new black bear populations in San Luis Obispo County and Monterey County. By the end of her PhD program, she will develop suggestions to improve the way black bear population size is estimated throughout California.
I sat down with Jamie in early July to talk about the work she is doing with black bears.
What led you to study black bears?
I’ve loved animals since I was young. I started working with large carnivores when I was in college and I just fell in love with watching how they interact with their environment. When I completed my undergrad degree, I had the option of going to vet school or graduate school. Ultimately, I decided that I love having a question and finding that answer, so I decided to go the research route and get my PhD. When I got to California it seemed that there was a need for people to be researching black bears. They’re incredibly smart animals that seem to be able to survive no matter what comes their way, which I find very fascinating.
Why is it important to know the population and geographic location of black bears?
Bears are expanding into human habitat and humans are expanding into bear habitat, which creates potential safety problems for both humans and bears. It's important for people to understand how to live with black bears. Human-wildlife conflict will continue to pose challenges as populations grow. A large component of preventing these conflicts is making sure food is not accessible to bears. That's the goal of CDFW's Keep Me Wild campaign.
How has the black bear population changed in recent years?
It has tripled in the last 25 years. It's estimated that in the 1980s, there were about 10,000 black bears statewide and now the estimates are over 30,000 black bears. There are a few reasons that could be. One is that grizzly bears are no longer around, so black bears have less competition and are able to expand into habitat range that was historically populated by grizzlies. Another hypothesis is legislation in the past 20 years that has changed hunting practices.
Can you tell us a bit more about black bear hunting?
Up to 1,700 black bears are hunted in California each year, and it's primarily for meat. Bears eat a variety of things and are very prone to getting different parasites. Some of those diseases can be passed to humans, including one that I focused on for part of my research, which is Trichinella. It can be passed from bears to humans when undercooked black bear meat is consumed. There are other parasites as well, but Trichinella is at the forefront because it has gotten humans sick in California in recent years.
Why are you working in San Luis Obispo County and Monterey County?
Those areas are really interesting because they're home to a relatively new population of black bears in California. Prior to 1950, there were no reports of black bears occurring in those two counties. It's hypothesized that it's because those two counties were typically inhabited by grizzly bears, which on the food chain are much higher up than black bears. It's likely that grizzly bears excluded black bears from that area before they were extirpated from California in the 1920s.
Some studies have shown that the black bears in the Central Coast region are most closely related to the southern Sierra Nevada black bears. We hypothesize that those bears have traveled up and over the transverse ranges and are moving their way up along the coast now. Through our work, we hope to get a better understanding of how black bears are inhabiting the two counties.
How is the black bear population estimated currently?
They are estimated based on hunter-harvest, which means that every time a bear is hunted, the hunter has to report to the Department of Fish and Wildlife. The information feeds into models to estimate population based on projected habitat throughout California.
This method has some limitations. One is that there are some counties where hunting does not occur and some counties where very little hunting occurs. So, you're estimating a total population based on data from very specific areas and then extrapolating to a much larger area. Another limitation is that hunters will preferentially go for larger bears, which are typically male. That can affect the models. But the real limitation and why we are interested in exploring other options for population estimation is that there are many areas where very little hunting occurs or hunting is illegal. We really want to get a better, more accurate idea of population in those areas.
What would be a better way to measure the population?
In my opinion, it would be to use a series of different methods that can adapt to California’s unique geographic areas and unique population. California is really interesting because we have such a diverse amount of habitat for black bears. You have bears that live in climates up north —a very seasonal lifestyle where they hibernate and it’s cold in the winter. And then you have bears in Santa Barbara who are not going to come across snow ever in their lives. It would be ideal to incorporate those differences through various methods. Hunter-harvest may be really great in areas where there is a high density of hunting, but then we have to explore other options where that’s not the case.
How are you collecting samples in Monterey and San Luis Obispo Counties?
Non-invasive methods are preferred because they don’t negatively affect the animals. One of the ways we do that is by using barbed wire hair snags. They are barbed wire corrals that have non-consumable bait in the middle. The bears are attracted to the scent of the bait and they’ll walk through the wire. It will snag some hair without them ever knowing. The field crew goes out once a week to inspect the barbed wire and collect the clumps of hair. Once we have the sample, we get it to the lab to get the DNA from the hair to identify if it’s a unique individual or a bear we have already tracked.
This method is called capture-mark-recapture. The basic idea is that if there’s a very large population, you should be catching new individuals regularly. However, if there’s a smaller population, you’re more likely to be catching the same individual.
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What do you use to draw the bears to the corrals?
We use two kinds of baits. One is very disgusting, but smells fantastic to the bear. It’s a mixture of cow blood that we get from butchers, and fish meal that ferments in a large bucket. It’s a very potent and disgusting smell. We pour that onto a pile of sticks, which creates a bait that can’t actually be consumed. We want the bears to be curious, but we don’t want them to come back constantly because it can skew our results. It’s called being “trap happy.” Our bait smells interesting, but the bears don’t get a reward for checking it out.
The other scent is sweet, either a honey or raspberry or anise oil. We use both because individual bears have their own likes and dislikes. We want to cater to all of the possible bears in that area.
What is your end goal for this project?
My goal is to inform both Fish and Wildlife and the public on the status of black bears in California and how we can manage them into the future. We’ll develop a report that we share with Fish and Wildlife, who are the main funders, and they'll disseminate that information to their employees and to the public. They’ll decide how they want to go further with this information.
I've gained a great set of mentors at UC Davis and the California Department of Fish and Wildlife. At the department, I’ve had the unique experience of working, both on the research side and as a scientific aide at their Wildlife Investigations Lab. My mentors have helped me hone in on my skills as a scientist and develop new skills that are going to help me be successful in the future.