Health of California Cougars - Interview with Dr. Winston Vickers

On September 3rd, WildFutures Research Assistant, Alexa Boesel, interviewed Dr. Winston Vickers.

WildFutures will be hosting Dr. Winston Vickers and Dr. Quinton Martins in a free webinar on September 20th.  Register here.

Alexa: You have been studying mountain lions in California for a very long time. What inspired you to first start working with them?

Winston: I started in 2002 when I went back to UC Davis to get a Master of Preventive Veterinary Medicine degree, focusing on wildlife population health and ecology, and anticipated doing my thesis in mountain lion health. I was spurred by an interest in large cats and carnivores and had assisted in some research in snow leopards, which I considered studying longer term. My wife and I had assisted an Earthwatch-funded snow leopard research project in Nepal with two PhD students. They studied non-invasively with cameras and tracking, particularly looking at predator-prey dynamics. However when I began my studies, mountain lions were the most locally available large cat in California (and North America for that matter) and UC Davis had an ongoing study in mountain lions, and thus they became the focus of my work.

I had started veterinary medicine with an interest in wildlife, with a preceptorship at the Oklahoma Zoo and then worked in a mixed animal hospital in rural North Arkansas. Then, I moved to California where I worked at a small animal and exotic pet hospital, occasionally working with wildlife.

Alexa: As a veterinarian, what are the most common diseases you see facing wild felids? And mountain lions specifically?

Winston: Being predators, mountain lions face a lot of diseases, as well as toxins, that their prey are exposed to. One example is Salmonella, which one lion in our study area died of. Another died of Valley Fever, or coccidioidomycosis, which humans can get in dry arid ecosystems. Our collaborators at Colorado State also study Feline Immunodeficiency Virus, or FIV, and other lentiviruses in domestic cats, wild bobcats, and mountain lions. Each of those species has their own strains of FIV, but our collaborators at Colorado State have detected a bobcat strain in mountain lions with unknown implications for the health of infected mountain lions.  

We have seen Feline Leukhemia virus (FelV) in a mountain lion which may have contributed to its death. We have also documented antibodies to plague in the mountain lion population, meaning the animals had been exposed to that disease agent.  None of our study animals have died of that disease to our knowledge, but that has occurred in other areas of the west. That is the same organism that infects humans occasionally in the western US and can be fatal. We presume mountain lions are usually exposed to this bacterial infection via rodents or other predators such as coyotes that mountain lions eat.

To date, we have not documented any major population effects from any particular disease, or any epidemics, but we are always watching for it. In one portion of our study area, we had a cluster of deaths from an unknown cause, but we suspected were due to an infectious agent of some kind, but we were unable to find a source.

Most deaths that we see are from car strikes, depredation permits and poaching. We certainly consider these in epidemiology studies. They provide an un-“natural” source of death, adding undue pressures to the populations that we study. Many of our populations are separated by highways, reducing gene flow, so genetic inbreeding and the potential for inbreeding depression and reduced reproduction also worry us a lot.

Alexa: What have been your personal challenges studying mountain lions? What has been most rewarding?

Winston: My personal challenges are primarily the difficulties of the actual work, and of funding the work. The work is physically challenging.  In order to capture a mountain lion in cage traps which is our primary method, we do a lot of hiking beforehand to find out via tracking and trail cameras where lion movement is occurring.  We bring in road killed deer as bait, sometimes carrying them long distances, and also carry in traps. We primarily capture at night, drive for many hours, and miss a fair amount of sleep. Getting funding is also challenging. The longest grants for projects are usually no more than 2-3 years, meaning that we are always on the search for more. Our equipment and time spent are expensive, with trucks, tracking collars, cameras, biologist salaries, etc., so grant money often doesn’t go as far as we would like.

However, the cumulative effects of our research has been immensely rewarding. Over the years, the research that we produced has affected public policy, making a difference for wildlife. We didn’t know much when we first started researching mountain lions. We were unsure there was anything wrong. One of the first things we found, is that there were many causes of premature death. Due to our research and research like it, we have made strides to reduce those premature deaths, documenting roadkill and depredation kill hot spots, increasing fencing along roadsides, reducing roadkill (including deer) which helps decrease overall car damage and money spent on repairs and increases human safety. We have documented the negative impacts of roads on mountain lion ecology, and therefore are making strides to reduce barrier effect of roads and genetic isolation.

To reduce deaths due to depredation permits, we have started to do a lot of work to educate owners of small livestock like goats, especially those who have just a few animals and who have the best potential for reducing the risks by bringing their animals into enclosures at night.  Working with the Mountain Lion Foundation, 4H clubs, and the UC Agricultural Extension program we are trying to educate people who live in mountain lion habitat on ways to reduce risks to their animals from mountain lions and other predators. The key is proper husbandry, which is important for kids to learn, thus the focus on working with 4-H.

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Alexa: What do you think is needed to coexist with these large carnivores if they are to have a future in the Bay Area?

Winston: The Bay Area and Southern California have a lot in common in that they are highly barriered areas with miles of roads and housing developments and a lot of mix between rural and urban areas. In areas like Sonoma there are a lot of owners of small livestock that when not properly protected can be killed by mountain lions, coyotes and bobcats, That can then result in the wild animal being killed.

A big part of the solution is educating people, and getting them to think about wildlife in their life. When people begin to consider wildlife, it drives public will, which then forces public policy and eventually, regulates individual behavior as it relates to wildlife. Essentially its an ask, to vote for wildlife, and elevate wildlife’s overall status in the ladder of importance, including politically.

Another important aspect of our work is helping people appreciate the vital role that large carnivores play in the ecosystem. If they were allowed to disappear, it would change the landscape irrevocably, in a way that humans probably wouldn’t like.

Alexa: Is there anything else you would like to share about your work?

Winston:  I will mention that some of my work is with the Institute for Wildlife Studies in northeastern California in a much more rural area, which provides an opportunity for comparison between the two types of habitats. In northeastern California, with less roads and more livestock, the primary cause of death we are seeing is from depredation permits.

As you can imagine, in populations far from any humans that are not hunted for sport, the primary reason for death would likely be intraspecific strife, or lions killing lions in competition for territory or mates.  Interestingly, in the Santa Monica Mountains in southern California, in an area where there are certainly also mortalities from depredation permits and car strikes, the National Park Service researchers there have also documented intraspecific strife (mountain lions killing other mountain lions) as a significant source of mortality. The reasons for this are unclear.

I think work like Quinton’s and mine allows us to see the scope of challenges that mountain lions living alongside humans are facing, and try to make some difference in their chances of long term persistence on the landscape that we humans are constantly altering. ​

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