The elusive mountain lion

Recent close encounters of the wild kind between humans and mountain lions have spurred intense public interest in mountain lion population management, or the lack thereof. Earlier this year, Proposition 197 was placed on the California ballot to repeal the "specially protected mammal" status of lions and open the door once again to legal hunting of one of California's largest predators.

The measure was motivated partly by the fear that a growing population of mountain lions would prove a threat to livestock and humans. But determining the size and location of mountain lion populations has been difficult. Existing studies of mountain lions are limited and based on a few individual radio-tracking studies, with some of the California data extrapolated from studies in other states. So Holly Ernest, a veterinarian and ecology doctoral candidate working with Walter Boyce in the School of Veterinary Medicine at UC Davis, set out to learn more about the elusive, wide-ranging and sometimes dangerous animals.

Ernest began a broad-based study of mountain lion population ecology, breeding structure and predator-prey interactions on a large geographic scale. The studies may reveal not only the number of lions in an area, but also their sex and information about their parentage. The methods used will augment information gained from radio-tracking studies and are less invasive to the animals.

Ernest is using scat samples taken from the field to identify DNA "fingerprints" for individual lions. Her findings can answer such questions as whether lions from Northern California interact and breed with those from the southern portion of the state. The studies can also provide information about the number of lions involved in a kill of bighorn sheep or mule deer, giving Ernest further insight into predator-prey interactions and an indirect idea of lion density in an area.

Ernest's work also lays the foundation for further studies of mountain lion reproduction. Once an animal has been DNA fingerprinted, researchers can then track the reproductive status of individual lions by measuring hormones in the scat to determine if the animal is pregnant. Researchers will also be able to monitor the health of lions by looking for parasites in their feces.

Ernest's work is funded by the School of Veterinary Medicine and the UC Davis Genetic Resource Conservation Program, and conducted in the labs of Michael Syvanen, medical microbiology and immunology, and Cecilia Torres Penedo, veterinary genetics.

From 1907 to 1963, lions were "bountied predators" in California. State, federal and individual agencies paid hunters to kill these "pest" animals. In 1969, their status was switched to "game animal," requiring people to buy a hunting license from the California Department of Fish and Game. Proposition 117 was passed in 1990, designating mountain lions as "specially protected mammals"--a distinction rarely given even to endangered species. An allotment of $30 million a year was set aside for the state to purchase deer and lion habitat, but no provision was made for research and management of mountain lion populations.

As a result of that legislation, lions could be killed only if they were causing harm or posing a threat to people, livestock or property. About 100 lions a year are killed for these reasons, with the numbers rising in recent years due to the increased contact of lions with people--two of the encounters were fatal in California.

Proposition 197 failed, but the state Legislature may place a similar measure on the November ballot. Like Proposition 197, it stipulates that $750,000 a year be used for research
and management, but prohibits sport hunting.

Ernest says the increase in mountain lion sightings and human-lion contact is likely due to several factors: decrease in lion habitat, increase in human numbers, greater human access to remote areas and perhaps an increase in lion populations. At this point, having a better understanding of mountain lions and their habitat can allow people to coexist with these elusive cats.